Transcriber’s Notes:
Underscores “_” before and after a word or phrase indicate _italics_
in the original text.
Equal signs “=” before and after a word or phrase indicate =bold=
in the original text.
Small capitals have been converted to SOLID capitals.
Illustrations have been moved so they do not break up paragraphs.
Typographical and punctuation errors have been silently corrected.
A TEXT-BOOK
OF
HORSESHOEING
FOR
_Horseshoers and Veterinarians_
BY
A. LUNGWITZ
FORMER MEMBER OF THE ROYAL SAXON VETERINARY COMMISSION,
LATE INSTRUCTOR IN THE THEORY AND PRACTICE OF HORSESHOEING,
AND DIRECTOR OF THE SHOEING SCHOOL OF THE
ROYAL VETERINARY COLLEGE IN DRESDEN, GERMANY
AND
JOHN W. ADAMS
PROFESSOR OF SURGERY AND OBSTETRICS,
AND LECTURER ON SHOEING IN THE VETERINARY SCHOOL,
UNIVERSITY OF PENNSYLVANIA
_ELEVENTH EDITION_
_WITH TWO HUNDRED AND TWENTY-NINE ILLUSTRATIONS_
PHILADELPHIA & LONDON
J. B. LIPPINCOTT COMPANY
Copyright, 1897, by J. B. LIPPINCOTT COMPANY.
Copyright, 1904, by J. B. LIPPINCOTT COMPANY.
Copyright, 1913, by J. B. LIPPINCOTT COMPANY.
PREFACE TO THE FIRST EDITION.
The inauguration of the law requiring horseshoers to be examined
emphasizes the need of a brief and easily understood text-book on
theoretical and practical horseshoeing. At the request of the _Royal
Veterinary Commission_, in charge of the Royal Veterinary School in
Dresden, and many interested individuals, I have attempted to meet
this need by condensing within the narrowest possible limits all that
is essential to the horseshoer in the practice of his profession.
The subject-matter has been cast into a logically arranged course of
instruction; all that is superfluous and is found only in exhaustive
treatises on shoeing has been omitted.
In order to make this elementary text-book more easy to understand,
numerous instructive illustrations have been incorporated, which were
taken partly from “Der Fuss des Pferdes,” by Leisering & Hartmann,
fifth edition, Dresden, 1882; partly from the journal _Der Hufschmied_,
and partly from drawings made specially for this work.
With the desire that this little book may find many friends and supply
them with valuable information, it is herewith given to the public.
A. LUNGWITZ.
DRESDEN, September, 1884.
TRANSLATOR’S PREFACE.
During the past nine years in which it has been my privilege to teach
horseshoeing to students of veterinary medicine in the University of
Pennsylvania, and to classes of horseshoers under the auspices of the
Master Horseshoers’ National Protective Association of America, I
have been forcibly impressed with the urgent need of a text-book of
horseshoeing that is adapted to the needs of beginners. In my opinion,
such a work must present a detailed description of the anatomy and
physiology of the legs below the middle of the cannons, and must
emphasize in unmistakable terms the definite relations which exist
between certain well-defined forms of the hoof and certain well-defined
standing positions of the limb. Only on this sure foundation can a
thoroughly scientific system of shoeing be based. Furthermore, the
teachings must be eminently practical, logically arranged, as brief as
is consistent with clearness, easy of comprehension by persons who are
unfamiliar with technical language, profusely illustrated, and moderate
in price.
Through the kindness of my respected friend and former teacher,
Professor A. Lungwitz, one of the highest authorities in all matters
pertaining to shoeing, and for many years a teacher in and the Director
of what I believe to be the best school of shoeing in the world, I am
enabled to present to the public this translation of his text-book
for students of shoeing. Written to meet requirements identical with
those existing today in the United States, and in scope and arrangement
exactly suited to both student and teacher, I am confident that it will
meet the favor that it merits.
THE TRANSLATOR.
PHILADELPHIA, 1904.
PREFACE TO THE ELEVENTH EDITION.
Since the publication in 1904 of a translation of the tenth edition of
_Der Lehrmeister im Hufbeschlag_, Prof. Anton Lungwitz, the author,
having reached the age of retirement has withdrawn from the activities
of the _Royal Saxon Shoeing School_, and has expressed a desire that
the translator assume entire responsibility for future editions.
To note the progress of farriery during the past ten years many
chapters have been revised, necessitating resetting, and sixty-nine new
illustrations have been added and many redrawn. It has seemed desirable
to discuss the effect of weight in the shoe in altering the flight of
the foot; to consider rubber pads so widely used in the United States,
and to direct attention to many innovations of more or less value, that
have appeared during recent years.
In preparing this edition I have had the cordial co-operation of the
publishers, to whom I hereby express deepest gratitude. I wish also to
record my appreciation for the many suggestions and other aid given me
by Mr. Franz Enge, Chief Farrier of the shoeing shop of the Veterinary
Hospital, University of Pennsylvania.
JOHN W. ADAMS.
UNIVERSITY OF PENNSYLVANIA, April, 1913.
CONTENTS.
PAGE
INTRODUCTION 13
The Object of Shoeing 13
PART I.
CHAPTER I.
THE GROSS ANATOMY OF THE HORSE.
BONES OF THE HEAD—BONES OF THE TRUNK 17
THE SPINAL COLUMN—BONES OF THE THORAX 17-19
BONES OF THE PELVIS—BONES OF THE LIMBS 19-21
JOINTS—MUSCLES—TENDON SHEATHS 21-24
THE FOOT.
=A. The Bones of the Foot= 24
The Cannon—The Long Pastern—The Sesamoid
Bones—The Short Pastern—The Pedal Bone—
The Navicular Bone 24-28
=B. The Articulations of the Foot= 28
I. THE FETLOCK-JOINT 28
The Suspensory Ligament 29
The Inferior Sesamoid Ligament 30
II. THE CORONARY JOINT 31
III. THE PEDAL ARTICULATION (COFFIN JOINT) 31
=C. The Locomotory Organs of the Foot= 32
The Anterior Extensor Tendon of the Phalanges—
The Perforatus Tendon—The Perforans Tendon 32-35
=Mucous Bursæ and Tendon Sheaths= 35
=Altering the Relative Tension of the Flexor Tendons
and Suspensory Ligament of the Fetlock-Joint= 36
=D. The Elastic Parts of the Foot= 38
The Lateral Cartilages—The Plantar Cushion 39, 40
=E. The Blood-Vessels and Nerves= 41
The Arteries of the Foot—The Veins of the Foot—
The Nerves of the Foot 41-44
=F. The Protective Organs of the Foot= 44
(_a_) THE HAIR-SKIN 44
1. The Epidermis 45
2. The Dermis 45
3. The Subcutaneous Tissue 45
(_b_) THE HOOF-SKIN, OR PODODERM 45, 46
1. The Perioplic Band 47
2. The Coronary Band 47
3. The Fleshy Wall 48
The Fleshy Leaves
(Podophyllous Tissue) 48, 49
4. The Velvety Tissue of the Sole 49
5. The Velvety Tissue of the Frog 49
(_c_) THE HORN CAPSULE OR HOOF 50-53
The Wall 50-53
The Bars 51, 52
The Layers of the Wall:
1. The Periople.
2. The Middle or Protective Layer.
3. The Leafy Layer (Keraphyllous Layer) 53-55
The Sole 55, 56
The Frog 57, 58
The Minute Structure of the Horn 58
Hard and Soft Horn 59
CHAPTER II.
THE FOOT IN ITS RELATION TO THE ENTIRE LIMB.
=A. Standing Positions of the Limbs= 62
(_a_) THE POSITIONS OF A FORE-LIMB VIEWED
FROM IN FRONT AND IN PROFILE 62-67
(_b_) THE POSITIONS OF A HIND LIMB VIEWED
FROM BEHIND AND IN PROFILE 67-69
=B. Forms of Feet, viewed from in Front,
from Behind, and in Profile= 69-72
=C. Lines of Flight of Hoofs in Motion= 72-75
=D. Influence of Weight upon Lines,
of Flight of Hoofs= 75, 76
=E. Forms of Hoofs= 77
The Hoof of the Regular Position—The Hoof of
the Base-Wide Position—The Hoof of the
Base-Narrow Position—Forms of Hind Hoofs—
The Wide and the Narrow Hoof—The
Characteristics of Healthy Hoofs 77-82
=F. Growth of the Hoof and Wear of the
Hoof and Shoe= 82-86
=G. Physiological Movements of the Hoof= 86-89
PART II.
CHAPTER III.
SHOEING HEALTHY HOOFS.
=A. Examination of a Horse Preliminary
to Shoeing= 90
=B. Raising and holding the Feet of the Horse
to be Shod= 92
=C. Removing the Old Shoes= 97
=D. Preparing the Hoof for the Shoe= 98
=E. Preparing the Hoof for going Barefoot= 102
=F. Making Shoes= 103
The Podometer—Making Front Shoes—Making
Hind Shoes—General Characteristics of
Shoes—A Shoe with Heel-Calks—A Shoe
with Toe- and Heel-Calks—Special
Characteristics of Shoes 103-116
=G. Choosing the Shoe= 116
=H. Shaping and Fitting Shoes—General
Considerations= 117
=Shaping and Fitting Shoes—Special
Considerations= 120
=Fitting Shoes to Saddlers and Hunters= 122
=Fitting Shoes to Runners= 123
=Fitting Shoes to Trotters and Pacers= 124
=Fitting Shoes to Heavy Draft-Horses= 125
=I. Nailing the Shoe, Horseshoe-Nails= 128
=K. Machine Shoes= 132
=L. Rubber Pads= 135
CHAPTER IV.
SHOEING HORSES THAT FORGE AND INTERFERE.
=A. Forging—Cross-firing= 138, 140
=B. Interfering= 142
CHAPTER V.
WINTER SHOEING.
1. ICE-NAILS (FROST-NAILS) 146
2. SHARP TOE- AND HEEL-CALKS 146
3. SCREW-CALKS 148, 155
4. PEG HEEL-CALKS 150
5. PEG TOE-CALKS 152
6. REMOVABLE HEEL-CALKS, THAT DO NOT REQUIRE
SHARPENING 154
CHAPTER VI.
HOOF NURTURE.
=A. Care of Unshod Hoofs= 157
=B. Care of Shod Hoofs= 159
Greasing and Soaking the Hoof 159
PART III.
CHAPTER VII.
GENERAL REMARKS CONCERNING THE SHOEING OF
DEFECTIVE HOOFS AND LAME HORSES.
GENERAL REMARKS 161-165
CLASSIFICATION OF DISEASES OF THE HOOF 165
CHAPTER VIII.
INFLAMMATIONS OF THE PODODERM (PODODERMATITIS).
1. NAILING 166
2. STREET-NAIL 170
3. CALK-WOUNDS OF THE CORONET 173
4. CORNS 174
5. INFLAMMATION OF THE HEELS 176
6. LAMINITIS (FOUNDER) 177
7. KERAPHYLLOCELE (HORN TUMOR) 181
CHAPTER IX.
DEFECTS OF THE HOOF.
=A. Changes of Form= 182
1. THE FLAT AND THE FULL HOOF 182
2. THE UPRIGHT OR STUMPY HOOF 184
3. THE CONTRACTED HOOF 185
(_a_) The Contraction of Wide Hoofs 189
(_b_) Contraction of the Sole 189
4. THE WRY HOOF 190
5. THE CROOKED HOOF 192
6. OSSIFICATION OF THE LATERAL CARTILAGE
(SIDE-BONE) 194
=B. Disturbances of Continuity of Hoof= 195
1. CRACKS 195
2. CLEFTS 203
3. LOOSE WALL 204
4. HOLLOW WALL 205
5. THRUSH OF THE FROG 206
CHAPTER X.
SHOEING MULES, ASSES, AND OXEN.
1. THE SHOEING OF MULES AND ASSES 207
2. THE SHOEING OF OXEN 207
INTRODUCTION.
Horseshoeing is an industry which requires, in equal degree, knowledge
and skill.
The word “horseshoeing” embraces various acts, especially preparing
the iron sole, the horseshoe; forming it and fitting it to the hoof,
whose ground-surface has been previously dressed in accordance with the
direction of the limb, and fastening it to the hoof by means of nails.
Owing to the complicated structure of the hoof, success in the practice
of horseshoeing requires a knowledge of the anatomy and physiology of
the horse’s body in general and of the foot in particular.
The object of shoeing is,—
1. To protect the hoof from excessive wear, and thus
render the horse continuously serviceable upon our
hard roads.
2. To prevent slipping and falling during the winter
season.
3. To so far remove the disadvantages of faulty
positions of the limbs that horses may render
good service, and, in some cases,
4. To cure or improve diseased or defective hoofs
or feet.
Horseshoeing, though apparently simple, involves many difficulties,
owing to the fact that the hoof is not an unchanging body, but
varies much with respect to form, growth, quality, and elasticity.
Furthermore, there are such great differences in the character of
ground-surfaces and in the nature of horses’ work that shoeing which
is not performed with great ability and care induces disease and makes
horses lame.
In view of these facts, a thorough training of the young horseshoer
in the principles and practice of his trade is not only greatly to be
desired, but is really essential to success; unreasoning work does
as much harm in this as in any other vocation. _A good common-school
education is necessary_ (more will do no harm). Further requisites
are a _healthy body_, not too tall, _liking for the work, aptness_,
an active, _reasoning mind, fearlessness, dexterity, a good eye for
proportion_, and, finally, _careful selection of a master-instructor_.
Theoretically educated, practically experienced and approved masters,
in whose shops all kinds of horses are shod, are to be preferred.
During his term of apprenticeship the young apprentice should _learn
to make drawings of horseshoes, of tools of the trade_, and of hoofs
of various forms, and should also make _one or more model shoes as an
indication of his ability_. After completing his time he should seek a
position in a first-class shop, either at home or abroad. A visit to
foreign lands will widen one’s mental horizon and make him a broader,
abler man in every respect. Later, opportunity will be given to some
(in Germany) to join the cavalry, and thus acquire a good education
in shoeing under the patronage of the government. Finally, a course
of instruction in a school of horseshoeing will convert an already
practical and intelligent horseshoer into a thoughtful, capable, expert
workman.
The scope of horseshoeing is by no means so narrow and insignificant
as it may appear, and since a knowledge of the anatomy and physiology
of the horse’s body in general, and of the foot in particular, is
necessary, it is evident that the schools of horseshoeing in which
one can get the best instruction are those in which there is not only
a regularly graded course of instruction, with demonstrations upon
dissected material and upon living horses, but also an abundance of
daily work at the forge and on the floor in the shoeing of horses. =A
course of four to six weeks is not sufficient.=
Furthermore, it should be borne in mind that schools of horseshoeing
are not for the purpose of instructing young men in all matters which
pertain to the trade, but only in the making of shoes, the critical
examination and management of hoofs, and the rational and skilful
performance of shoeing. For this reason it is not advisable for young
men to attend a school of horseshoeing until they have at least
completed their apprenticeship.
HORSESHOEING.
PART I.
CHAPTER I. THE GROSS ANATOMY OF THE HORSE.
The supporting structure of the horse’s body is the =bony framework= or
skeleton (Fig. 1, page 18). We distinguish in the skeleton the bones of
the head, trunk, and limbs.
The =bones of the head= are numerous and, excepting the lower jaw, are
solidly united with one another. In general, we distinguish in the head
only the upper and lower jaws (1 and 1′). Both form various cavities;
for example, the cranial cavity, in which the brain lies, the orbital
cavities (eye-sockets), the nasal passages, and the mouth. Besides, the
teeth are set in the jaws.
The =trunk= comprises the bones of the spinal column, thorax, and
pelvis.
The _spinal_ or _vertebral column_ (2 to 6), which bears the head at
its anterior end, is the chief support, of the entire skeleton. It
consists of from fifty-two to fifty-four single and irregular bones
called vertebræ, placed in the upper part of the median vertical plane
of the body. Each vertebra, with the exception of those of the tail
(coccygeal or caudal vertebræ), is traversed by a large opening called
the vertebral foramen. The vertebræ are placed end to end in a row,
and through them runs a continuous large canal called the _vertebral_
or _spinal canal_, in which lies the spinal cord. The horse has seven
cervical, eighteen dorsal, six lumbar, five sacral, and sixteen to
eighteen caudal vertebræ. The sacral vertebræ are grown together to
form one piece called the sacrum.
[Illustration: FIG. 1.
SKELETON OF THE HORSE.—1, bones of the head; 1′, lower jaw; 2, cervical
vertebræ; 3, dorsal vertebræ; 4, lumbar vertebræ; 5, sacral vertebræ
(sacrum); 6, coccygeal vertebræ; 7, ribs; 8, sternum (breast-bone);
9, pelvis; 9′, ilium; 9″, ischium; 10, scapula (shoulder-blade); 11,
humerus; 12, radius; 13, ulna; 14, carpus (knee); 15, large metacarpal
bone (cannon); 16, rudimentary metacarpal bones (splint-bones); 17, os
suffraginis (long pastern); 18, os coronæ (short pastern); 19, os pedis
(hoof-bone); 20, sesamoid bones; 21, femur; 22, patella (knee-pan,
stifle); 23, tibia; 24, fibula; 25, tarsus, or hock; 26, large
metatarsal bone (cannon); 27, rudimentary metatarsals (splint-bones);
28, os suffraginis (long pastern); 29, os coronæ (short pastern); 30,
os pedis (hoof-bone, “coffin bone”); 31, sesamoid bones.]
The _thorax_ is formed by the ribs and the breast-bone or sternum.
The horse has eighteen ribs on each side (7), and all articulate with
the dorsal vertebræ. The first eight pairs unite by their lower ends
directly to the sternum or breast-bone, and are therefore called _true
ribs_, while the last ten pairs are only indirectly attached to the
sternum, and are consequently called _false ribs_. The sternum (8) lies
between the forelegs, and helps to form the floor of the chest cavity.
The space enclosed by the bones of the thorax is called the thoracic,
pulmonary, or chest cavity, and contains the heart and lungs. The
_bones of the pelvis_ form a complete circle or girdle. The upper part,
called the ilium (9′), articulates on its inner side with the sacrum
(5), while its outer side is prolonged to form a prominent angle, which
is the support of the hip, and is called the “point of the hip.” The
posterior part of the pelvis is called the ischium (9″), and that part
lying between the ilium and the ischium and forming part of the floor
of the pelvis is called the pubis.
The space between the thorax and the pelvis, bounded above by the
lumbar vertebræ and shut in below and on the sides by the skin and
muscular walls of the belly (abdomen), is called the _abdominal
cavity_. This cavity opens directly into the pelvic cavity, and
contains the stomach, intestines, liver, spleen, pancreas, kidneys, and
a part of the generative organs. The thoracic and abdominal cavities
are separated by a muscular partition, the _diaphragm_.
The =bones of the limbs= may be likened to columns, upon which the body
rests; they articulate with one another at various angles, are tubular
in structure, and strong.
The bones of the =fore-limbs= _do not articulate directly with the
bones of the trunk_, but are attached to the body by means of the skin
and muscles. From above to below we distinguish the following bones:
1. The _scapula_, or shoulder-blade (10), a flat, triangular bone,
prolonged at its upper border by a flat, very elastic cartilage, called
the scapular cartilage. At its lower end the scapula articulates with—
2. The upper end of the _humerus_ (11), forming the _shoulder-joint_
(scapulo-humeral articulation). The humerus articulates at its lower
end with—
3. The _radius_ (12) and the _ulna_ (13), to form the _elbow joint_.
These two bones are the basis of the _forearm_. The ulna, smaller and
weaker than the radius, lies behind and projects above it to form the
point of the elbow. The lower end of the radius articulates with—
4. The _carpus_, or _knee_ (14), which comprises seven small, cubical
bones disposed in two horizontal rows, one above the other. The upper
row comprises four bones and the lower row three. The lower row rests
upon—
5. The large metacarpal or _cannon bone_, and the two rudimentary
metacarpal or _splint-bones_. The lower end of the radius, the upper
ends of the metacarpal bones, and the small carpal bones together form
the carpal or _knee-joint_ (wrist of man). Of the metacarpals, the
middle one is the largest, longest, strongest, and most important, and
is called the _large metacarpal_, _cannon_, or _shin-bone_ (15). It
articulates at its lower end with the os suffraginis, or long pastern
(17), and with the two small sesamoid bones (20). On each side of
the upper part of its posterior surface lie the two long, slender
splint-bones (16). The inner splint-bone is sometimes affected with
bony thickenings (exostoses) called “splints.”
6. The bones of the _phalanges_ (all bones below the cannon) will be
fully described in another place.
The bones of the =hind limbs= articulate _directly_ with the pelvis at
the hip-joint. They are stronger than the bones of the anterior limbs.
We distinguish the following bones in the hind legs:
1. The highest bone in the hind limb is the _femur_ (21). It is the
strongest bone in the entire body. It lies in an oblique direction
downward and forward, and at its lower end articulates with—
2. The _patella_ (22), the _tibia_ (23), and the _fibula_ (24), to form
the _stifle-joint_ (knee of man). The patella plays over the anterior
surface of the lower end of the femur. The fibula is small, and lies
against the upper and outer side of the tibia. The latter at its lower
end articulates with—
3. The bones of the tarsus, or _hock_ (25), which are six small,
irregular bones disposed in three rows, one above another. The _os
calcis_, or _heel-bone_, and the _astragalus_ are in the uppermost
row, and are the most important. The former projects above the true
hock-joint from behind, to form a long lever, the upper end of which
is called the “point of the hock,” and the latter articulates with the
tibia. The tarsal (hock) bones articulate below with—
4. The _metatarsal bones_ (26 and 27), which are longer, and the cannon
narrower from side to side, than the corresponding metacarpal bones,
but are otherwise similar.
5. The _phalanges_ of a hind limb (28 to 31) are also narrower than
those of a fore-limb, but are nearly alike in other respects.
All the horse’s bones present small, but more or less distinct openings
(nutrient foramina) for the passage of blood-vessels and nerves.
Many bones possess roughened elevations and depressions, to which
ligaments, tendons, or muscles are attached. With the exception of
the os pedis, all bones are enveloped in a sort of “bone-skin” called
=periosteum=. The bones unite among themselves to form either _movable_
or _immovable unions_. A movable union between two or more bones is
termed a “joint,” or =articulation=. The articulating ends of the
bones, presenting on one side a convex surface (head or condyle) and on
the other a corresponding concave surface (glenoid or cotyloid cavity),
are covered with elastic _articular cartilage_. The bones are bound
together by means of =ligaments=, which are tough, fibrous, cord-like,
or sheet-like structures. Ligaments are either (1) _capsular_ or (2)
_funicular_ (cord-like). Every articulation in the limbs possesses a
capsular ligament, and all, except the shoulder-joint, have several
funicular (cord-like) ligaments. The capsular ligaments are lined
upon their inner face with a delicate membrane (synovial membrane)
which secretes the _synovia_, or “joint-water,” whose function is to
lubricate the joint and prevent friction; they enclose the joint in
a sort of air-tight cuff or sack. The funicular ligaments are very
strong and often large, and are the chief means of union of the
bones. The immovable articulations are termed _sutures_; they are
found principally in the head. The mixed joints are found between the
bodies of the vertebræ, each two of which are united by an elastic
fibro-cartilage which, in the form of a pad, lies between them, and by
its elasticity allows of very slight movement, though the spinal column
as a whole can execute manifold and wide movements, as shown by the
neck and tail.
Joints which permit motion in all directions are known as =free
joints=; such are the shoulder- and hip-joints (ball-and-socket
joints). Those which admit of motion in but two directions (flexion
and extension), and often to a very limited extent, are called
=hinge-joints=,—_e.g._, the elbow, hock, and fetlock. The joints
between the long and short pasterns and between the latter and the
pedal bone are imperfect hinge-joints, because they allow of some other
movements besides flexion and extension. The articulation between
the first and second cervical vertebræ (atlas and axis) is called a
=pivot-joint=.
The skeleton represents a framework which closely approaches the
external form of the body, and by reason of its hardness and stiffness
furnishes a firm foundation for all other parts of the body. By
reason of the great variety of position and direction of the bones,
and of the fact that changes of position of each single part of this
complicated system of levers may result in the greatest variety of
bodily movements, we can readily understand how the horse is enabled
to move from place to place. Of course, the bones have no power of
themselves to move, but this power is possessed by other organs that
are attached to the bones. These organs are the =muscles=, and, owing
to their ability to contract and shorten themselves, and afterwards to
relax and allow themselves to be stretched out, they furnish the motive
power that is communicated to and moves the bones.
[Illustration: FIG. 2.
OUTER MUSCLES OF THE HORSE.—1, cervical trapezius; 2, dorsal trapezius;
3, mastoido-humeralis; 4, great dorsal muscle; 5, long abductor of
the arm; 6, long extensor of the forearm; 7, large extensor of the
forearm; 8, short extensor of the forearm; 9, sterno-trochinus (deep
pectoral); 10, sterno-aponeuroticus; 11, great serratus; 12, common
extensor of the metacarpus; 13, common extensor of the toe (anterior
extensor); 14, common extensor of the long pastern (lateral extensor);
15, oblique extensor of the metacarpus; 16, external flexor of the
metacarpus; 17, internal flexor of the metacarpus; 18, oblique
flexor of the metacarpus; 19, fascia lata; 20, superficial gluteus
(anterior portion); 21, middle gluteus; 22, superficial gluteus
(posterior portion); 23 and 24, femoral biceps; 25, semitendinosus; 26,
semimembranosus; 27, anterior extensor of the toe; 28, lateral extensor
of the toe; 29, perforans muscle (deep flexor of toe); 30, oblique
flexor of the phalanges; 31, perforatus tendon (superficial flexor of
phalanges); 32, Achilles tendon (ham-string).]
The muscles of the body massed together are the red flesh which
we observe in every slaughtered animal. They are not, however, so
shapeless as they appear while in this condition; on the contrary, they
present well-arranged muscular layers of variable size, thickness,
length, and position. (See Fig. 2.) The muscles clothe the skeleton
externally, give the body its peculiar form, and, by their special
power of contraction, change the relative positions of the bones and
thus make it possible for the animal to move. For this reason, the
muscles are called the =active=, and the bones the =passive=, organs
of motion. By carefully examining a muscle it will be found to consist
of actual, minute, reddish, _muscular fibres_. As a rule, muscles
terminate in more or less strong, glistening, fibrous cords called
=tendons=, or fibrous sheets termed aponeuroses, by which they are
attached to the bones. In the limbs are muscles terminating in very
long tendons, which act as draw-lines upon the distant bones of the
foot (long and short pasterns and pedal bone) and set them in motion.
Such long tendons are enclosed in sheaths of thin, membranous tissue,
known as _tendon sheaths_. The inner surface of such a sheath is in
direct contact with the surface of the tendon, and secretes a thin
slippery fluid (synovia) which lubricates the tendon and facilitates
its gliding within the sheath.
As long as the bones, articulations, muscles, and tendons of the limbs
remain healthy, just so long will the legs maintain their natural
direction and position. Frequently, however, this normal condition of
the limbs is gradually altered by disease of the bones, joints, and
tendons, and defects in the form and action of the lower parts of the
limbs arise that often require attention in shoeing.
THE FOOT.
A. The Bones of the Foot.
Since the horse is useful to man only by reason of his movements, his
foot deserves the most careful attention. The horseshoer should be
familiar with all its parts. Fig. 3 shows the osseous framework of
the foot, consisting of the lower end of the cannon bone (_A_), the
long pastern (_B_), the two sesamoid bones (_C_), the short pastern
(_D_), and the pedal bone (_E_). The lower end of the cannon, or large
metacarpal bone (_A_) exhibits two convex articular surfaces (condyles)
separated by a median ridge running from before to behind, and all
covered by articular cartilage. On both the external and the internal
aspects of the lower end of the cannon are small uneven depressions in
which ligaments take their attachment.
[Illustration: FIG. 3.]
The condyles of the cannon articulate with the os suffraginis (long
pastern) and the two sesamoids (Figs. 3, _C_, and 4, _B_) in such a
manner that in the forefeet the cannon makes an angle with the long
pastern of from one hundred and thirty-five to one hundred and forty
degrees, and in the hind feet of from one hundred and forty to one
hundred and forty-five degrees.
The =long pastern= (first phalanx) (Fig. 4, _A_) is about one-third the
length of the cannon; its upper and thicker end presents two condyloid
cavities (_a_) (glenoid cavities), separated by a median groove, which
exactly fit the condyles and ridge at the lower end of the cannon.
The lower end of the long pastern is smaller than the upper, and is
provided with two condyles, between which is a shallow groove (_e_).
The anterior face of the bone is smooth, rounded from side to side, and
blends into the lateral borders. The posterior face is flatter, and
shows a clearly marked triangle to which ligaments attach.
The two =sesamoid bones= (Fig. 4, _B_) are small, and somewhat
pyramidal in shape, and, lying against the posterior part of the
condyles of the cannon bone, increase the articular surfaces at the
upper end of the long pastern.
[Illustration: FIG. 4.
Os suffraginis with both sesamoid bones in position, as in Fig. 3. _A_,
os suffraginis; _B_, sesamoid bones; _a_, upper joint-surface of long
pastern; _b_, joint-surface of sesamoid bones; _c_, roughened surface
at upper end; _d_, roughened surface at lower end, both for attachment
of ligaments; _e_, lower joint-surface.]
The =short pastern= (second phalanx) (Figs. 5 and 6) lies under the
first phalanx and above the os pedis; it is somewhat cubical in
shape. Its upper articular surface (Fig. 5, _a_) presents two glenoid
cavities to correspond with the condyles of the first phalanx. The
lower articular surface (Fig. 5, _d_) resembles the lower end of the
first phalanx. The upper posterior border of this bone is prominent and
prolonged transversely (Fig. 6, _a_), to serve as a _supporting ledge_
for the first phalanx, as a point of attachment for the perforatus
tendon, and as a gliding surface for the perforans tendon.
[Illustration: FIG. 5.
Short pastern (os coronæ) viewed in front and in profile: _a_, upper
joint-surface; _b_, anterior surface; _c_, lateral surface; _d_, lower
joint-surface.]
[Illustration: FIG. 6.
Short pastern seen from behind: _a_, smooth surface over which the
perforans tendon glides; _b_, lower joint-surface.]
The lowest bone of the limb is the =third phalanx= or =os pedis= (Fig.
7). In form it is similar to the hoof. The _anterior or wall-surface_
(_a_) is rough, like pumice stone. Above and in front is the _pyramidal
eminence_ to which the tendon of the anterior extensor of the phalanges
attaches. Behind, the bone extends backward to form the _inner_ and
_outer branches_ (_c, c_) or wings of the os pedis. The _upper_,
articular surface (_b_) slopes backward and downward. The _lower_,
solar or plantar surface (Fig. 8, _a_) is slightly concave, and
presents posteriorly a half-moon-shaped excavation, with a roughened
border called the _semilunar crest (c)_, to which the perforans tendon
attaches; just above this crest are two small holes (_e_) known as the
_plantar foramina_, through which the plantar arteries pass into the
bone. The surfaces of wall and sole come together in a sharp edge,
which is circular in its course. It is easy to tell whether a pedal
bone is from a fore or a hind limb; the os pedis of a hind leg has
a steeper and more pointed toe, and a more strongly concaved solar
surface than the same bone of a fore-leg. Not only is the outline of
the sharp inferior border of the os pedis of a _front foot more rounded
at the toe_, but when placed on a flat surface the _toe does not touch_
by reason of being turned slightly upward, much as a shoe designed to
give a “rolling motion.” The os pedis of a _hind foot is narrower from
side to side_ (pointed), and _does not turn up at the toe_.
[Illustration: FIG. 7.
Os pedis seen in profile and in front; _a_, anterior face with
pyramidal eminence above; _b_, joint-surface; _c_, wings or branches
of hoof-bone; _d_, notch which, by the attachment of the lateral
cartilage, is converted into a foramen and leads to _e_, the preplantar
fissure.]
[Illustration: FIG. 8.
Lower surface of hoof-bone; _a_, anterior portion covered by the
velvety tissue of the sole; _b_, wing of the os pedis; _c_, semilunar
crest, to which the perforans tendon attaches; _d_, plantar fissure
leading to _e_, plantar foramen.]
The right and left hoof-bones are also, as a rule, easily distinguished
by variations in the surfaces of wall and sole. The shape of the os
pedis corresponds to the form of the horny box or hoof, and therefore a
knowledge of this bone is absolutely necessary.
The =navicular bone= (os naviculare, nut-bone, Figs. 9 and 10) is
an accessory or sesamoid bone to the os pedis. It is a small bone,
transversely elongated and situated behind and below the os pedis and
between the wings of the latter. It adds to the articular surface of
the pedal joint. Its under surface is smooth, and acts as a gliding
surface for the perforans tendon, which is quite wide at this point.
[Illustration: FIG. 9.]
[Illustration: FIG. 10.
Fig. 9 represents the upper surface of the navicular bone; Fig. 10 the
lower surface of the same: _a_, anterior border; _b_, slight elevation
in middle of under surface.]
The long axes of the three phalanges (os suffraginis, os coronæ, and os
pedis) should unite to form a straight line, when viewed either from
in front or from one side; that is, the direction of each of these
three bones should be the same as the common direction of the three
considered as a whole.
In young colts both the long and short pasterns are
in three parts and the pedal bone in two parts, all
of which unite later in life to form their respective
single bones.
In mules and asses the os pedis is comparatively
small and narrow. In cattle all three phalanges are
double, and split hoofs cover the divided os pedis.
B. The Articulations of the Foot.
There are three articulations in the foot—namely, the fetlock,
coronary, and pedal joints. All are hinge-joints, the fetlock being a
perfect hinge-joint, and the other two imperfect hinge-joints. Each
has a _capsular ligament_, and also several _funicular_ or cord-like
_ligaments_ which are placed at the sides of (lateral ligaments), or
behind (on the side of flexion) the joints.
I. The =fetlock= or =metacarpo-phalangeal articulation= is formed by
the condyles at the lower end of the cannon bone and the glenoid
cavities formed by the union of the articular surfaces of the sesamoids
and the upper end of the first phalanx. The following ligaments are
about this joint:
[Illustration: FIG. 11.]
1. _Two lateral ligaments_, an external and an internal (Fig. 11, _a_).
2. _Two lateral sesamoid ligaments_ (_f_).
3. An _intersesamoid ligament_ (Fig. 12, _b_), a thick, fibrous mass,
binding the sesamoid bones almost immovably together, extending above
them and presenting on its posterior face a smooth groove, in which
glide the flexor tendons of the phalanges (perforans and perforatus).
4. The _suspensory ligament_ of the fetlock (Figs. 11, _c_, 12, _c_,
and 13, _c_, pages 29 and 30). This may also be called the superior
sesamoid ligament. It is a long and very powerful brace, originating
on the lower row of carpal bones (bones of the hock in the hind leg)
and on the upper end of the cannon between the heads of the two
splint-bones, and dividing at the lower third of the cannon into two
branches (_c_), which are attached one to each sesamoid bone. Below
these bones these two branches are prolonged obliquely downward and
forward on opposite sides of the long pastern to pass into the borders
of the anterior extensor tendon of the toe at about the middle of the
long pastern (Fig. 14, _b′_, page 32).
[Illustration: FIG. 12.]
[Illustration: FIG. 13.
Fig. 11 shows a side view, and Figs. 12 and 13 a posterior view of the
phalangeal bones, with their articular ligaments. The lettering is the
same in all three figures: _a_, lateral ligament of fetlock-joint; _b_,
intersesamoid ligament; _c_, suspensory ligament of the fetlock; _d_,
median branch of inferior sesamoid ligament; _d′_, lateral branches
of inferior sesamoid ligament; _e_, deep inferior sesamoid ligament;
_f_, lateral sesamoid ligaments; _g_, inferior coronary ligaments; _h_,
superior coronary ligaments; _h′_, median coronary ligaments; _i_,
lateral pedal ligament; _k_, lateral coronary ligament and suspensory
ligament of the navicular bone; _l_, interosseous ligament.]
5. The _inferior sesamoid ligament_ (Figs. 11, _d′_, 12, _d_, _d′_,
and 13, _d′_, _E_). This originates at the lowest part of the sesamoid
bones and intersesamoid ligament, and consists of _three parts_ or
branches. The _median branch_ (_d_) is the longest and strongest, and
takes its lower attachment in the middle of the fibro-cartilaginous lip
found on the upper border of the posterior face of the second phalanx.
The _two lateral branches_ (_d′_) approach each other as they descend,
and terminate on the sides of the roughened triangle on the posterior
face of the first phalanx.
6. The _deep inferior sesamoid ligament_ (Fig. 13, _e_) is quite short,
and consists of a number of distinct, thin fibrous bands lying directly
against the bone and entirely covered by the median and lateral
inferior sesamoid ligaments. These fibrous bands cross one another in
passing from the sesamoids to the first phalanx.
II. The =coronary joint= is the simplest of the three articulations of
the foot. The long pastern furnishes two condyles and the short pastern
two glenoid cavities. Besides a capsular ligament there are—
1. _Two lateral coronary ligaments_ (_k_) and,
2. _Six posterior coronary ligaments_,—namely, _two superior_ coronary
ligaments (_h_), _two median_ coronary ligaments (_h′_), and _two
inferior_ coronary ligaments (_g_).
III. The =pedal articulation= (“coffin” joint) is an imperfect
hinge-joint, and is formed by the condyles at the lower end of the
short pastern and the two glenoid cavities in the united upper surfaces
of the pedal and navicular bones. Besides the _capsular ligament_
(Figs. 12 and 13, _l_), which binds all three bones together, there are
the following accessory ligaments:
1. _Two strong lateral ligaments_, an external and an internal (Fig.
11, _i_), whose posterior borders are lost in the lateral cartilages
which cover them.
2. _Two lateral suspensory ligaments of the navicular bone_ (_k_).
They begin on the posterior border and ends of the navicular bone,
and terminate on the lower part of the anterior surface of the os
suffraginis, where they are lost in the lateral ligaments of the
coronary articulation.
3. The _lateral ligaments_ of the lateral _cartilages_, _navicular
bone_, and _os pedis_. They are short, and unite the navicular bone
with the os pedis and lateral cartilages.
Of the three phalangeal articulations, the pedal is the only one that
permits of any lateral movement; hence it is an imperfect hinge-joint.
C. The Locomotory Organs of the Foot.
Though the muscles are the organs which produce motion, the horseshoer
need concern himself only with the tendons of those muscles which
extend and flex the phalanges. These tendons are either =extensors= or
=flexors=. The extensors lie on the _anterior face_ and the flexors on
the _posterior face_ of the phalanges.
[Illustration: FIG. 14.
Right forefoot viewed from in front and from the external side: _a_,
anterior extensor tendon of the toe; _b_, suspensory ligament of the
fetlock; _b′_, branch of the same passing forward and uniting with the
extensor tendon of the toe; _c_, extensor tendon of the os suffraginis
(absent in the hind leg), called the lateral extensor.]
The _anterior extensor of the phalanges_ (Fig. 14, _a_) extends
the long and short pasterns and the hoof-bone; it is broad, and
made somewhat broader by receiving the branches of the suspensory
ligament (_b′_) that come from the sesamoid bones. It takes a firm
attachment on the pyramidal eminence of the os pedis. In the forefeet
the long pastern has a special extensor tendon (_c_), which is known
as the _lateral extensor_. When the muscles to which these tendons
are attached act,—that is, when they draw themselves together, or
_contract_, as we term this action,—the foot is carried forward
(extended).
There are _two flexor tendons_ of the phalanges,—namely, the
_superficial_ (perforatus tendon) and the _deep_ (perforans tendon).
[Illustration: FIG. 15.
Right forefoot seen from behind: _a_, lower end of the perforans
tendon, cut through and hanging down, so that its anterior surface is
visible; _a′_, lower expanded end (plantar aponeurosis) of this tendon,
which attaches itself to the semilunar crest of the os pedis; _a″_,
shallow groove which receives the slight elevation on the under surface
of the navicular bone; _a‴_, piece of the perforans tendon enclosed
by the ring formed by the perforatus tendon; _b_, perforatus tendon
bent over backward so that its anterior surface is visible; _b′_, ring
of the perforatus tendon; _b″_, terminal branches of the same; the
perforans tendon passes through the space between these two branches;
_c_, navicular bone; _d_, suspensory ligament of the same; _e_, smooth
surface on the os coronæ over which the perforans tendon glides; _f_,
the smooth groove (sesamoid groove) on the posterior surface of the
intersesamoid ligament for the gliding of the perforans tendon; _g_,
body of the suspensory ligament of the fetlock; _g′_, terminal branches
of the same, attaching to the sesamoid bones.]
1. The _superficial flexor_ or _perforatus tendon_ (Figs. 15, _b_,
and 16, _a_, _b_) lies behind, immediately under the skin, and covers
the deep flexor or perforans tendon. At the gliding surface between
the sesamoid bones (Fig. 15, _f_) it broadens, and forms a ring or
tube (Fig. 15, _b′_) through which the perforans tendon (_a‴_) passes,
while a short distance farther down it bifurcates, or divides into two
branches (Figs. 15, _b″_, and 16, _b_), which terminate, one on either
side, partly on the inferior lateral borders of the first phalanx
and partly on the fibro-cartilage of the second phalanx. It acts
simultaneously on the long and short pasterns.
2. The _deep flexor_ or _perforans tendon_ (Figs. 15, _a_, and 16,
_c_) is cylindrical and stronger than the perforatus tendon; above
the fetlock-joint it lies between the perforatus and the suspensory
ligament of the fetlock. At the sesamoid bones it passes through the
ring formed by the perforatus tendon (Fig. 15, _b′_), then becomes
broad and double-edged, passes between the two terminal branches of the
perforatus, glides over the fibro-cartilage of the second phalanx and
over the inferior surface of the navicular bone, and finally ends on
the semilunar crest of the third phalanx. In common with the perforatus
tendon it flexes the foot.
[Illustration: FIG. 16.
Right forefoot seen from behind and a little from the external side:
_a_, perforatus tendon; _b_, terminal branches of the same; _c_,
perforans tendon; _d_, annular ligament which attaches to the sesamoid
bones: _d′_, the “x” ligament, which attaches by four branches to the
os suffraginis; _d″_, an upper branch of the same (the lower branches
are not shown in the figure); _e_, reinforcing sheath of the perforans
tendon, covering the under surface of the latter and attached by
its branches at _e′_ to the lower end of the os suffraginis; _f_,
suspensory ligament of the fetlock.]
If at a point a few inches above the fetlock a limb be cut through
from behind, the knife will pass successively through the following
structures: skin, perforatus tendon, perforans tendon, suspensory
ligament, cannon bone, lateral extensor tendon, anterior extensor
tendon, and, lastly, the skin on the anterior surface of the limb. The
flexor tendons are frequently thickened and shortened by inflammation
due to injury, and as a result the foot is pulled backward and the hoof
gradually becomes more nearly upright,—_i.e._, stubby, steep-toed.
A knowledge of the normal condition of the tendons is, therefore,
absolutely necessary to the horseshoer. Both flexor tendons are
embraced and held in place by ligaments and fascia passing out from
the phalanges (Figs. 16, _d′_, and 24, _e_, _f_). The extensor and
flexor tendons essentially contribute to the strong union of the
phalangeal bones, and especially to the support and stability of the
fetlock-joint. The gliding of the tendons is made easy by the secretion
of a lubricating fluid, called synovia, from the inner surface of the
sheaths which surround them. In thin-skinned well-bred horses with
sound limbs one can not only distinctly feel the tendons through the
skin, but can see their outline. _When the tendons and bones are free
from all inflammatory thickenings, and the tendon sheaths are not
visibly distended, we say that the leg is “clean.”_
Mucous Bursæ and Tendon Sheaths.
Accessory to the tendons, there are in the foot roundish, membranous
sacs (mucous bursæ) and membranous tubes (tendon sheaths). Both contain
a liquid resembling synovia (“joint-water”), which facilitates the
gliding of the tendons. These bursæ and sheaths are often distended to
form soft tumors, known as hygromata (“wind-puffs,” “wind-galls”).
(_a_) =Mucous Bursæ.=—They lie beneath tendons at those places where
the tendons pass over bony prominences.
1. The mucous bursa of the anterior extensor tendon of the toe is about
the size of a walnut, and lies between the tendon and the capsular
ligament of the fetlock-joint (Figs. 17, _g_, and 18, _e_).
2. The mucous bursa of the extensor tendon of the long pastern (lateral
extensor) is somewhat smaller, and lies, likewise, beneath the tendon,
between it and the capsular ligament of the fetlock-joint (Fig. 17,
_h_).
3. The mucous bursa of the navicular region lies between the under
surface (gliding surface) of the navicular bone and the flexor pedis
perforans tendon (deep flexor). Its width equals the length of the
navicular bone, and it extends upward and downward beyond the bone.
Above, it is separated from the sheath of the perforans tendon (“great
sesamoid sheath”) by a membranous partition; below, it passes to the
attachment of the perforans tendon to the semilunar crest of the os
pedis.
(_b_) There is but one tendon sheath in the foot—the sheath common to
the two flexor tendons (great sesamoid sheath). It encloses the flexor
tendons from the middle third of the cannon down to the middle of the
short pastern, and is intimately united with the flexor pedis perforans
tendon (Fig. 17, _f_, _f′_, _f″_, _f‴_. Fig. 18, _d_, _d′_, _d″_, _d‴_).
[Illustration: FIG. 17.
Right forefoot seen from the external side; _f_, _f′_, _f″_, _f‴_,
great sesamoid sheath (tendon sheath); _g_, mucous bursa beneath
anterior extensor tendon of the toe; _h_, mucous bursa beneath extensor
tendon of long pastern; _i_, synovial distension of the fetlock-joint;
7, suspensory ligament; 9, cannon bone; 10, outer sesamoid bone; 12,
fetlock-joint; 13, lateral cartilage; 14, suspensory ligament of the
lateral cartilage. (Ellenberger in Leisering’s Atlas and Veterinary
Anatomy, Sisson, Saunders.)]
[Illustration: FIG. 18.
Right forefoot seen from the inner side; _d_, _d′_, _d″_, _d‴_, great
sesamoid sheath; _e_, mucous bursa beneath anterior extensor tendon of
the toe; _f_, synovial distension of fetlock-joint; 10, inner sesamoid
bone; 11, “x” ligament; 14, fetlock-joint; 15, lateral cartilage; 16,
suspensory ligament of lateral cartilage (Ellenberger in Leisering’s
Atlas and Veterinary Anatomy, Sisson, Saunders.)]
Altering the Relative Tension of the Flexor Tendons and Suspensory
Ligament of the Fetlock-Joint.
The body-weight imposed at the fetlock-joint is supported, in large
part, by the suspensory ligament; somewhat less weight is borne by the
perforans tendon, and a still smaller amount by the perforatus. The
coronary joint is supported chiefly by the perforatus, assisted by
the perforans. The pedal joint is pressed forward and upward by the
perforans tendon passing in a curve beneath the navicular bone. Each of
these three structures bears its normal proportion of the body-weight
when the three phalanges, as viewed from the side, form a continuous
straight line from the fetlock-joint to the ground. In such a case the
obliquity of the long pastern will be the same as that of the toe (see
Foot-Axis, p. 70).
[Illustration: FIG. 19.
Right forefoot viewed from the external side: _A_, os coronæ; _B_, os
pedis; _C_, external lateral cartilage; _a_, lateral pedal ligament;
_b_, ligament uniting the lateral cartilage with the os coronæ; _c_,
aponeurosis joining lateral cartilage and os pedis.]
_Raising the toe_ by means of a tip, a full shoe with thinned branches
or a toe-calk, _or paring away the quarters_ will tilt the os pedis
backward, break the foot-axis backward in the pedal joint and to a less
extent in the coronary joint, and increase the tension of the perforans
tendon considerably and of the perforatus slightly. These tendons
tightening behind the fetlock-joint force it forward, causing the long
pastern to stand steeper, and taking some strain from the suspensory
ligament. Hence, _the perforans tendon is under greatest tension, and
the suspensory ligament under least tension, when the foot-axis is
broken strongly backward_.
_Shortening the toe, or raising the quarters_ by heel-calks or
thickened branches, will tilt the os pedis forward, break the foot-axis
forward in the pedal joint, and will _greatly lessen the tension of the
perforans tendon_. The aggregate tension of perforans and perforatus
tendons being diminished, the fetlock sinks downward and backward,
the long pastern assumes a more nearly horizontal direction, and the
tension of the suspensory ligament is increased. Thus, _the perforans
tendon is under least tension, and the suspensory ligament under
greatest strain, when the foot-axis is broken strongly forward_.
D. The Elastic Parts of the Foot.
[Illustration: FIG. 20.
Os pedis and inner face of one lateral cartilage; _a_, toe of os pedis;
_a′_, pyramidal eminence to which the extensor tendon attaches; _a″_,
wing of pedal bone; _b_, lateral cartilage; _C_, points of attachment
of suspensory ligament of lateral cartilage; _d_, point of insertion
of ligament to the short pastern; _e_, point of insertion of ligaments
from navicular bone.]
All bodies which under pressure or traction change their form, but
return again to their original shape as soon as the pressure or
traction ceases, are called _elastic_ or _springy_. Nearly all parts of
the horse’s foot, except the bones, possess more or less elasticity.
The _lateral cartilages_ and the _plantar cushion_ are elastic to a
high degree, but the _coronary band_, the _laminæ_, the _articular
cartilage_, and the horny box or _hoof_ are less elastic. This property
or characteristic is possessed by the respective parts of the foot in
accordance with their function, location, and structure.
[Illustration: FIG. 21.
Plantar cushion seen from below: _a_, base or bulb of the plantar
cushion; _b_, summit; _c_, median lacuna or cleft in which lies the
“frog-stay” of the horny frog.]
[Illustration: FIG. 22.
Plantar cushion seen from above: _a_, base (bulbs) of same; _b_,
summit; _c_, suspensory ligament of plantar cushion; _d_, place at
which the elastic ligament connecting the os suffraginis and the
lateral cartilage unites with the plantar cushion.]
The =two lateral cartilages= (Figs. 19, _C_ and 20, _b_) are irregular,
quadrangular plates, attached to the wings of the os pedis, and
extending so far upward and backward that one can feel them yield
to pressure on the skin above the coronet, and can thus test their
elasticity. The perforans tendon and the plantar cushion lie between
the lateral cartilages, and on the sides and behind are partially
enclosed by them. The internal concave surface of the lateral cartilage
(Fig. 20) is attached to the plantar cushion, the os pedis, and the
navicular bone, and, like the external, slightly convex surface, is
covered with many blood-vessels (veins) Fig. 25, _B_.
[Illustration: FIG. 23.
Section lengthwise through middle of the plantar cushion: _a_, glome
(bulb) of heels; _b_, apex or point of fleshy frog; _c_, fibro fatty
tissue of plantar cushion; _d_, median cleft which receives the
frog-stay of the horny frog.]
The =plantar cushion= (Figs. 21, 22, 23) is composed almost entirely
of yellow elastic and white fibrous tissues, with adipose (fat) cells
distributed throughout their substance. It is similar in form to the
horny frog, and lies between it and the perforans tendon (Fig. 24,
_a_). The bulbs are formed by the posterior thicker portion which lies
between the lateral cartilages and is divided into two parts by the
cleft or median lacuna (Figs. 21, _a_, and 23, _d_). The summit is
attached to the plantar face of the os pedis in front of the semilunar
crest, and the bulbs are attached to the lateral cartilages. It is
covered inferiorly by the velvety tissue of the frog (pododerm).
[Illustration: FIG. 24.
Right forefoot viewed from below, behind, and the external side. This
figure shows clearly the position of the plantar cushion. The external
lateral cartilage and the tissues covering the plantar cushion and
under surface of the os pedis (velvety tissue of the sole and fleshy
frog) have been removed: _a_, fleshy frog or plantar cushion; _a′_,
bulbs of plantar cushion; the remaining visible parts belong to the
so-called “fleshy frog;” _a″_, groove (median lacuna) in the lower
surface of the fleshy frog, in which lies the frog-stay of the horny
frog; _b_, suspensory ligament of the plantar cushion passing out of
the bulbs; _b′_, small elastic cords passing to the lateral cartilage;
_c_, elastic ligament coming from the lateral cartilage and uniting
with the suspensory ligament of the plantar cushion; _d_, small
tendinous cord beginning in the skin behind the fetlock-joint and
ending on the os suffraginis in common with _b_ and _c_; _e_, tendinous
reinforcing sheath of the perforans tendon; _f_, reinforcing stay of
the perforatus tendon; _g_, perforatus tendon; _h_, perforans tendon;
_i_, suspensory ligament of the fetlock; _k_, plantar surface of the os
pedis, to which the plantar cushion is joined by fibrous bands.]
E. The Blood-Vessels and Nerves.
Vessels which carry blood from the heart to the tissues are called
=arteries=, while those which return the blood to the heart from the
tissues are called =veins=. Arteries and veins are connected by very
small, thread-like vessels called _capillaries_, which originate in the
smallest arteries and are so minute that they can not be seen without
the aid of a microscope. The capillaries penetrate the soft tissues in
every direction, and finally unite to form small veins. For our purpose
we need consider only the arteries and veins.
The =arteries= carrying blood from the heart ramify and subdivide in
all parts of the body, and thus reach the foot. They are thick-walled,
very elastic tubes, =without valves=, and carry =bright-red= blood,
which flows in spurts, as can be seen when an artery is cut. If a
finger be pressed lightly over an artery lying near the surface, the
blood-wave can be felt as a light stroke (pulse). The character of
the pulse is important, because in inflammations of the pododerm or
horn-producing membrane of the foot we can ascertain by feeling that
the pulse is stronger than usual in the large arteries carrying blood
to the inflamed foot.
On either side of the phalanges below the fetlock-joint there lies an
artery called the _digital artery_ (Fig. 25, _a_). The pulse can be
felt in it as it passes over the fetlock at _A_, Fig. 25. It gives off
the following collateral (side) branches: 1. The _artery of the first
phalanx_ (perpendicular artery), with anterior and posterior branches.
2. The _artery of the plantar cushion_, which supplies with blood the
plantar cushion, the velvety tissue of the sole and frog, the bar
portion of the coronary band, and the sensitive laminæ of the bars. 3.
The _coronary artery_, which carries blood to the coronary band, os
coronæ, ligaments of the coronary and pedal joints, flexor tendons, and
skin.
The terminal branches of the digital arteries are the _preplantar_ and
_plantar ungual arteries_. The preplantar artery passes through the
notch in the wing of the os pedis, then along the preplantar fissure,
splitting up into many branches, which spread over and penetrate the
porous surface of the os pedis. The plantar artery courses along the
plantar fissure, enters the plantar foramen, and passes into the
semilunar sinus of the os pedis, where it unites with the terminal
branch of the opposite digital artery, forming the _semilunar arch_.
[Illustration: FIG. 25.
Side view of forefoot, showing blood-vessels and nerves: _a_, digital
artery; _b_, anterior artery of the os suffraginis; _d_, anterior
coronary artery, or circumflex artery of the coronet; _e_′, preplantar
ungual artery; _f′_, inferior communicating arteries passing out from
the semilunar artery of the os pedis, through minute holes just above
the lower border of the bone; they unite to form (_f″_) the circumflex
artery of the toe; _A_, digital vein; _B_, superficial venous plexus of
coronary band and lateral cartilage; _C_, podophyllous venous plexus;
_G_, circumflex vein of the toe; 1, plantar nerve; 2, anterior digital
branch of same; 3, posterior digital branch of same; 4, small cutaneous
branches of same.]
After the arterial or pure blood passes through the capillaries it
is collected by the =veins=, to be returned to the heart; then it is
driven to the lungs for purification, and is again returned to the
heart, from whence it is pumped through the arteries to all parts of
the body.
[Illustration: FIG. 26.
Foot viewed from below and behind: _a_, digital arteries; _c_, arteries
of the plantar cushion; _f‴_, small branches of the semilunar artery
of the os pedis, which ramify in the velvety tissue of the sole; _A_,
digital vein; _B_, venous plexus of the heels or bulbs; _D_, solar
venous plexus; _G_, circumflex vein of the toe; 3, posterior digital
branch of the plantar nerve; 4, cutaneous branches of the same.]
The veins are more numerous than the arteries; they have thinner walls,
and the larger ones are provided with =valves= that prevent the impure
blood from flowing backward. The veins carry impure or =dark-red= blood
towards the heart, and if one is opened the dark blood flows in a
steady stream; it does not spurt. The great number of veinlets in the
lower parts of the foot form a complex net-work (plexus) of vessels
which are in such manifold and close union with one another that
checking the flow of blood in one part does not seriously interfere
with the flowing of the blood towards the larger veins. The following
are the most important of these net-works of veins or venous plexuses:
(1) the _solar venous plexus_ (Fig. 26, _D_); (2) the _podophyllous
venous plexus_ (Fig. 25, _C_); (3) _superficial coronary venous
plexus_ (Fig. 25, _B_); (4) _bulbar venous plexus_ (Fig. 26, _B_). All
these plexuses of small veins contribute to form the _digital veins_
(Figs. 25 and 26, _A_).
=Nerves= are roundish white cords which come from the brain and spinal
cord; they generally accompany arteries. They divide and subdivide
into smaller and smaller branches till they become invisible to the
naked eye and are lost in the tissues. The nerves that are found in the
foot come from the spinal cord, and because the largest nerves of the
foot accompany the digital arteries they are called _digital nerves_
(Fig. 25, 1). The branches ramify throughout all parts of the foot
except the horny box and the hair. Nerves, according to their use or
function, are classed as _motor_ and _sensory_. The motor nerves end in
muscles which they stimulate to action and control. The sensory nerves
terminate in the skin and in the soft tissues just under the horny box
or hoof (pododerm), and render these parts sensitive; that is, they
convey certain feelings, as, for example, the pain caused by bruising,
pricking, or close-nailing, to the brain and consciousness.
F. The Protective Organs of the Foot.
The protective organs are the skin and the horny box or hoof.
The _external skin_, or _hide_, covers the entire body; in the feet it
covers the bones, tendons, and ligaments, even passing in under the
hoof and directly covering the os pedis. This portion of the skin,
enclosed by the hoof and therefore invisible, is called the _pododerm_
or foot-skin. In Germany it is called the _hoof-skin_ (huflederhaut),
because it is a continuation of the outer visible skin, and because
it secretes the hoof,—that is, the hoof is produced by it. That part
of the skin which is covered with hair is known as the external or
_hair-skin_.
(_a_) =The hair-skin= (Fig. 27, _a_) consists of _three_ superposed
_layers_,—(1) the _external_ superficial layer, or _epidermis_; (2) the
_middle_ layer, _derm_ or leather-skin (so-called because leather is
made from it); (3) the _internal_ layer, or _subcutaneous connective
tissue_.
1. The _external layer_, or _epidermis_, is composed merely of single
flattened, horn-like cells (scales) lying side by side and over one
another, and uniting to form one entire structure,—a thin, horn-like
layer, without blood-vessels or nerves. It extends over the entire
surface of the body, and protects the underlying, very sensitive middle
layer from external influences. The oldest cell-layers lie on the outer
surface, and are being continuously brushed off in patches or scales,
while new ones are constantly being formed on the outer surface of the
middle layer.
2. The _middle layer_, _leather-skin_ or _dermis_, is composed of
solid, fibrous, and elastic tissues, and contains many blood-vessels,
small nerves, sweat-and oil-glands, and hair follicles from which the
hair grows. The hair upon the posterior surface of the fetlock-joint is
usually long and coarse, forming a tuft known as the “foot-lock,” which
encloses a horny spur, called the ergot. Common-bred horses have, as
a rule, larger and coarser footlocks than thoroughbreds. The derm or
leather-skin, which produces the hair and epiderm, is the thickest and
most important layer of the skin.
3. _The inner layer, or subcutaneous tissue_, unites the middle layer
with the muscles, tendons, ligaments, bones, or other structures. It is
that loose fibrous mesh or net-work through which the butcher cuts in
removing the hide from the carcass.
[Illustration: FIG. 27.
Foot from which the horny capsule or hoof, has been removed by
prolonged soaking: _a_, skin; on the left the hair has been rubbed
away; _b_, perioplic band; _c_, coronary cushion; _d_, podophyllous
tissue (fleshy leaves); at the lower border of the figure can be seen
the minute thread-like processes or villi which grow down from the
lower end of each fleshy leaf.]
(_b_) =The hoof-skin= (Figs. 27 and 28, _b_, _c_, _d_), or pododerm,
is completely enclosed by the hoof. Although it is only an extension of
the derm or middle layer of the hair-skin, it differs from the latter
in structure and relations.
[Illustration: FIG. 28.
Foot from which the near half of the horny wall and a greater part
of the so-called fleshy wall have been removed, in order to show the
relation of the lateral cartilage to adjacent structures: _a_, vertical
section of the skin prolonged downward through the pododerm (foot-skin)
to show clearly that the latter is but a continuation of the former;
_a′_, hairless place on the skin; _b_, perioplic band; _b′_, line
indicating the upper border of the same; _b″_, surface of section of
the periople, or perioplic horn-band; _c_, coronary cushion; _c′_,
(left) line which marks the upper border of the coronary cushion;
_c″_, section of wall at the toe; _d_, podophyllous tissue (sensitive
laminæ); _e_, horny sole; _f_, white line; _g_, horny frog; _h_, fleshy
frog; _i_, lateral cartilage.]
In order to study the pododerm we should not wrench the hoof off with
violence, but should allow the foot to partially decompose by leaving
it for six to eight days at ordinary room temperature; it can then
be removed without injuring the pododerm. After the hoof has been
removed the entire pododerm presents a more or less dark-red color
(flesh-color), which is due to the great number of blood-vessels that
it contains. For this reason different parts of the pododerm have
received the prefix “fleshy,” as for example, fleshy wall, fleshy sole,
fleshy frog, etc. The pododerm is what the uninformed horseshoer calls
the “quick.” I will here remark that the three layers of the external
or hair-skin are represented in the foot; however, the epidermis is
in an entirely different form,—namely, the horny box or hoof. The
internal layer or subcutaneous tissue of the hair-skin is absent in
those parts of the foot where the pododerm covers the os pedis. There
remains, therefore, only the middle layer, derm, or _pododerm, which
secretes the hoof_, and which is the prolongation and representative
of the middle layer of the hair-skin. The pododerm is distinguished
from the derm of the hair-skin chiefly by the absence of hairs, oil-
and sweat-glands, and the presence on its outer surface of fleshy,
sensitive laminæ and small thread-like projections called villi.
The pododerm consists of five different parts: the _perioplic band_,
the _coronary band_, the _sensitive laminæ_ (podophyllous tissue), the
_velvety tissue of the sole_, and the _velvety tissue of the fleshy
frog_.
1. The _perioplic band_ (Fig. 28, _b_) is a narrow ridge, about
one-fifth to one-fourth of an inch wide, lying between the hair-skin
and the coronary band. Somewhat broader at the toe than on the sides,
it broadens out near the bulbs of the heels, over which it passes to
end in the velvety tissue of the fleshy frog. It is separated from
the coronary band by a narrow depression called the _coronary furrow_
(Moeller). The surface of the perioplic band glistens faintly, and is
thickly studded with numerous thread-like projections called villi,
which are from one-twenty-fourth to one-twelfth of an inch in length.
=The perioplic band secretes the soft horn of the perioplic ring and
the perioplic or varnish-like outer layer of the wall.=
2. The _coronary band_ (Fig. 27, _c_) lies between the perioplic band
and the sensitive laminæ or fleshy leaves. It presents a prominent
convex band or cushion about three-fourths of an inch wide, which
extends entirely around the foot from one bulb of the heel to the
other. In front it directly covers the anterior extensor tendon of the
toe, and at the sides the lateral surfaces of the os coronæ and the
upper part of the lateral cartilages, while farther back towards the
heels the lateral cartilages project considerably above both coronary
and perioplic bands. The coronary band is more convex (rounded) in
front than on the sides of the foot, and is flattened in the region
of the bulbs of the heels. Its surface is thickly covered with villi,
which are longer and stronger than those of the perioplic band. At the
bulbs of the heels the coronary band turns forward and inward along the
fleshy frog nearly to its summit. This portion of the coronary band
is from one-third to one-half an inch wide, and is called the _bar
portion of the coronary band_. It is also covered with villi, which are
directly continuous with those of the fleshy frog. =The coronary band
secretes the principal part (middle layer) of the horny wall of the
hoof, including the bar portion (bars) of the wall.=
[Illustration: FIG. 29.
Plantar surface of a foot deprived of its horny capsule by prolonged
maceration: _a_, laminæ of the bars; _b_, velvety tissue of the sole;
_c_, velvety tissue of the frog; _d_, median cleft of the fleshy
frog, into which the velvety tissue dips; _e_, bulbar portion of the
perioplic band, which passes insensibly into the velvety tissue of the
fleshy frog.]
3. _The fleshy wall_, or _podophyllous tissue_ (Figs. 27, 28, _d_,
and 29, _a_), is all that portion of the pododerm on which there are
fleshy leaves. This leafy tissue covers the anterior surface of the
os pedis and the lower portion of the external surface of the lateral
cartilages. At the bulbs of the heels it turns inward at a sharp angle
and extends forward and inward, between the bar portion of the coronary
band and the posterior part of the velvety tissue of the sole, nearly
to the middle of the solar surface of the foot, to form the _laminæ
of the bars_ (Fig. 29, _a_). The fleshy wall and fleshy bars are not
covered with villi, but with numerous prominent, parallel, _fleshy
leaves_ placed close together, each of which runs in a straight line
downward and forward from the coronary band to the lower border of the
os pedis. Between the fleshy leaves are deep furrows in which, in a
foot which has not been deprived of its horny capsule, lie the horny or
insensitive leaves of the wall. The fleshy leaves (podophyllous laminæ)
are related to one another somewhat as the leaves of a book; their
posterior borders are attached to the body or basement membrane of the
fleshy wall, while their anterior borders and sides are free. At their
upper ends immediately below the coronary band the leaves are quite
narrow, but they gradually increase in width down to the middle, and
thereafter maintain that breadth to the lower border of the os pedis,
where they terminate in free, fleshy villi, which differ in no respect
from those of the fleshy sole. The number and length of the fleshy
leaves vary; in a medium-sized foot there are about five hundred, while
in a large foot there may be as many as six hundred. On the anterior
surface of the os pedis the leaves are thickest and longest; on the
sides and quarters they gradually decrease in length, while in the bar
region they are the shortest and gradually disappear near the anterior
ends of the bars. The width of the leaves decreases as they become
shorter. Viewed with the naked eye the leaves appear flat and smooth,
but under the microscope one can see on both sides of a fleshy leaf
numerous small, fleshy leaflets parallel to one another and extending
lengthwise with the larger leaf. The large ones are called _principal
leaves_, and the small ones are known as _collateral leaves_, or simply
as _leaflets_.
=The fleshy leaves (podophyllous tissue) secrete
the horny leaves (keraphyllous tissue) and serve to
bind the horny wall to the pododerm. The strength
of this union is due largely to the dovetailing of
the horny leaves and their leaflets with the fleshy
leaves and their leaflets.=
4. _The fleshy sole_ or _velvety tissue of the sole_ (Fig. 29, _b_) is
that part of the pododerm which covers all the under surface of the
foot except the plantar cushion, the bar laminæ, and the bar portion of
the coronary band. It is sometimes slate-colored or studded with black
spots, but is usually dark-red. It is thickly set with villi, which are
especially long and strong[1] near its periphery. =The fleshy sole=
covers the solar plexus, or net-work of veins, and =secretes the horny
sole=.
[1] In order to see the length, thickness, and abundance of the villi
of the pododerm, place the foot deprived of its hoof in a clear glass
jar and cover it with water, renewing the latter until it is no longer
tinged with blood.
5. _The velvety tissue of the frog_ (Fig. 29, _c_) covers the lower
surface of the plantar cushion, and in the region of the bulbs (_e_)
passes insensibly into the perioplic band. In comparison with the
fleshy sole, it has much finer and shorter villi and contains fewer
blood-vessels. =It secretes the soft, horny frog.=
[Illustration: FIG. 30.
Side view of hoof recently removed: _a_, the perioplic horn-band; it
is swollen from prolonged maceration in water; the upper border shows
adhering hairs; the inner surface (perioplic groove) presents many
minute openings; _a′_, the perioplic horn-band broadens in passing over
the bulb or glome of the heel, and is finally lost in the horny frog;
_a″_, section of wall removed. That part of hoof on the right of _b_ is
called the toe; between _b_ and _c_ is the side wall or “mamma,” and
between _c_ and _d_ the “quarter;” _e_, projecting horny frog; _f_,
coronary groove with numerous minute openings; _g_, keraphyllous layer
of the wall (horny leaves).]
(_c_) =The horn capsule= or =hoof= (Fig. 30) is the entire mass made up
of the horn-cells secreted from the whole surface of the pododerm, and
next to the shoe is the organ with which the horseshoer has most to do.
The horn capsule or hoof is nothing more than a very thick epidermis
that protects the horse’s foot, just as a well-fitting shoe protects
the human foot. The hoof of a sound foot is so firmly united with the
underlying pododerm that only an extraordinary force can separate them.
In its normal condition the hoof exactly fits the soft structures
within it; hence it is evident that local or general contraction of the
hoof must produce pressure on the blood-vessels and nerve-endings of
the pododerm, disturb the circulation of the blood and the nutrition of
the foot, and cause pain.
[Illustration: FIG. 31.
Plantar surface of right fore-hoof: _a_, _a_, bearing-surface of the
toe; _a_, _b_, bearing-surface of the side walls or mammæ; _b, c_,
bearing-surface of the quarters; _d_, buttress, or angle formed by wall
and bar; _e_, bar; _f_, sole; _f′_, branches of the sole; _g_, white
line; it passes between the sole and bars and ends at _g′_; _h_, horny
frog; _i_, branches of the frog; _k_, heels, bulbs, or glomes of the
hoof; _l_, median lacuna of horny frog. Between the bars and the horny
frog lie the lateral lacunæ of the frog.]
The hoof is divided into three principal parts, which are solidly
united in the healthy foot,—namely, the =wall=, the =sole=, and the
=frog=. That part of the hoof which is almost wholly visible when
the foot is on the ground (Fig. 30, _b_, _c_), and which protects
the foot in front and upon the sides, is known as the =wall=. In
position, course, direction, and arrangement of its parts it simulates
the different parts of the pododerm from which it is developed. It
extends from the edge of the hair just above the coronary band to the
ground; backward it gradually decreases in height (length), passes
around the bulbs of the heels, and turns forward and inward (Fig. 32,
_d_, _e_, and 34, _a_, _b_) to form the =bars=, which are finally
lost in the edge of the sole near the summit of the frog. It thus
forms at each heel an angle (Fig. 31, _d_, and 32, _d_) known as a
buttress, which encloses a branch of the horny sole. Externally the
wall is smooth, covered with the varnish-like periople, and presents
indistinct ring-like markings (Fig. 30). Its inner surface, on the
contrary, presents a great number of horn-leaves which are spoken of
collectively as the _keraphyllous tissue_ (Figs. 32, _g_, and 35,
_f_). The upper or =coronary border= of the wall is thin and flexible,
and on its inner aspect is the =coronary groove=, into which fits the
=coronary band= (Fig. 30, _f_). The lower border of the wall, called
the “=bearing-edge=” or _plantar border_ (Fig. 31, _a_), is the one to
which the horseshoe is fastened. By dividing a hoof from before to
behind along its median line, _outer_ and _inner_ halves or _walls_ are
produced, and by dividing the entire lower circumference of the wall
into five equal parts or sections, a =toe=, two =side walls or mammæ=,
and two =quarters= will be exhibited (Figs. 32 and 33). In order to
designate these regions of the hoof still more accurately, they are
spoken of as outer and inner toes, quarters, and heels.
[Illustration: FIG. 32.
Wall and bars seen from below: _a_, toe; _b_, side wall, or mamma; _c_,
quarter; _d_, buttress; _e_, bar; _g_, horn-leaves; _h_, space occupied
by the frog.]
_The direction_ (slant) _and length of the wall_ vary in one and the
same hoof, as well as between fore and hind hoofs. The portion of the
wall of fore-hoofs is the most slanting,—that is, forms the most acute
angle with the surface of the ground,—and is also the longest. Towards
the quarters the wall gradually becomes very nearly vertical; in almost
all hoofs the posterior part of the quarters slants downward and inward
towards the median vertical antero-posterior plane of the foot. At the
same time the wall, in passing back from the toe to the heel, becomes
gradually shorter in such a manner that the heights of the toe, side
walls, and quarters are related to one another about as 3: 2: 1 in
front hoofs and as 4: 3: 2 in hind hoofs. The outer wall is, as a rule,
somewhat more slanting than the inner. Viewing a foot in profile, the
toe and heel should be parallel; that is, the line from the hair to the
ground at the toe should be parallel to the line from the hair to the
ground at the buttress. =All deviations of the wall from a straight
line= (outward or inward bendings) =are to be regarded as faults or
defects=.
[Illustration: FIG. 33.
A hoof in profile; _a_, toe (one half); _b_, side wall; _c_, quarter.]
[Illustration: FIG. 34.
Vertical section through the middle of a hoof, with horny frog removed,
to show the position of the bar: _a_, _b_, marks the line at which the
wall bends forward and inward towards the median line of the foot to
become the bar. Bar runs forward and passes imperceptibly into the sole
_c_; _a_, _a′_, the light shading shows the part of the bar that was in
contact with the horny frog.]
The _thickness of the wall_ is also variable. In front hoofs the wall
is thickest at the toe, and becomes gradually thinner towards the
quarters, while in hind hoofs, there is very little difference in
the thickness of the wall of the toe, sides, and quarters. _The more
slanting half of the hoof is always the thicker_; thus, for example,
the outer wall of a base-wide foot is always longer and more oblique
than the inner wall, and is also thicker. According to Mayer, the
thickness of the wall at the toe varies from three- to five-eighths of
an inch, and at the quarters from two to three-eighths of an inch.
These measurements are dependent upon the size and breeding of the
horse.
[Illustration: FIG. 35.
The outer wall of the hoof has been removed by cutting vertically
through the middle of the toe, down to the upper surface of the sole,
then horizontally backward into the quarter, and, finally, upward
through the quarter: _a_, perioplic horn-band; _b_, coronary groove; it
turns inward and forward at _c_ to form the upper border of the bar;
_d_, surface of section of the wall at the toe; _d′_, at the quarter;
_e_, surface of horizontal section of the wall near its lower border;
_f_, keraphyllous layer of the wall; at _f′_ it turns forward and
inward to cover the bar; _f″_, horny leaves standing free and passing
insensibly into the white horn of the middle layer or true wall; _g_,
horny sole; _h_, white line; _i_, small horn-spur in middle of toe;
_k_, part of horny frog which is in intimate union with the upper edge
of the bar; _l_, frog-stay of horny frog; it divides the trough-like
depression of the upper surface of the frog into _m_, the two upper
channels of the frog.]
The horn wall is composed of _three superposed layers_. These from
without to within are: (1) the =periople=, secreted by the perioplic
band. It is very thin, glistening, and varnish-like in appearance, and
covers the entire outer surface of the wall, except where it has been
removed by the rasp, and prevents rapid evaporation of moisture from
the horn. (2) The middle or =protective layer= (Fig. 35, _d_) is the
thickest, strongest, and most important of the three layers; it forms
the principal mass of the wall, and is developed or secreted by the
coronary band, which fits into the coronary groove. There are in the
coronary groove a great number of small, funnel-shaped openings into
which project the horn-producing villi or papillæ of the coronary band.
(3) The =inner layer= or =keraphyllous layer= (Fig. 35, _f_) consists
of prominent, parallel horn-leaves lying side by side over the entire
inner surface of the middle layer of the wall, and continuing beyond
the buttresses to the ends of the bars (Fig. 35, _f′_). This layer of
horn-leaves (keraphyllous layer) has in a general way about the same
shape and arrangement as the layer of fleshy leaves (podophyllous
layer) which secretes it; for the horn-leaves fit in with the fleshy
leaves in such a way that every fleshy leaf is embraced by two
horn-leaves, and every horn-leaf by two fleshy leaves (Fig. 36). The
keraphyllous layer and the horn of the inmost part of the middle or
protective layer are always white, even in pigmented (colored) hoofs.
[Illustration: FIG. 36.
Cross-section of keraphyllous and podophyllous laminæ (horny and fleshy
leaves): _a_, inmost part of the solid wall; the horn-tubes approach
very close to the horny leaves; _b_, body of the podophyllous membrane;
_c_, horny portion of a horn-leaf directly continuous with the middle
or principal layer of the wall; _c′_, a rudimentary horn-leaf that does
not reach the body of the podophyllous membrane; _c″_, cross-section
of horny leaves from the sides of which branch many secondary leaves
(leaflets) composed of soft (young) horn-cells. These soft cellular
horn-leaflets dovetail with the podophyllous or fleshy leaflets;
_d_, podophyllous laminæ extending from the body of the podophyllous
membrane; _d′_, podophyllous laminæ which have branched in their course
to the wall, and thus given rise to _c′_, rudimentary horn-leaves;
_d″_, cross-section of podophyllous leaflets extending from the
sides of the podophyllous leaves; each two such leaflets secrete a
keraphyllous leaflet between them; _e_, injected arterial vessels.]
[Illustration: FIG. 37.
Vertical section of the horny sole magnified: _a_, funnel-shaped
openings which contain the horn-producing villi of the fleshy sole;
they are of various sizes; _b_, horn-tubes; _c_, intertubular horn.]
[Illustration: FIG. 38.
Horny frog, with the posterior portion of the perioplic horn-band and
the periople which covers the quarters removed from the hoof as one
piece by maceration: _a_, trough-shaped depression of upper surface,
which is divided posteriorly into the two upper channels of the frog by
_b_, the frog-stay; _c_, part of the frog that is joined to the bar and
forms the lateral wall of the depression (channels) on upper surface
of frog; _d_, lateral surface of horny frog which, in its upper part,
adheres to the bar, but below, at _d′_, lies free; _e_, point or summit
of the frog; _f_, perioplic horn-band; _f′_, periople of the quarters.]
The =horn sole= (Fig. 31, _f_, and Fig. 35, _g_) is secreted by the
velvety tissue of the sole. A sole from which the loose flakes of
old horn have been removed is about as thick as the wall. It covers
the under surface of the foot, and presents upon its upper surface a
convexity which exactly fits into the concavity on the under surface
of the os pedis. This upper surface is thickly covered by a multitude
of minute funnel-shaped openings for the reception of the villi of the
velvety tissue of the sole (Fig. 37). The lower surface of the sole
is more or less concave, rough, uneven, and often covered by loose
scales of dead horn. Behind, the sole presents a triangular opening
whose borders lie partly in contact with the horny frog and partly
with the bars. This opening or re-entering angle divides the sole into
a _body_ (Fig. 31, _f_) and two wings or _branches_ (Fig. 31, _f′_).
The outer border of the sole unites through the medium of the =white
line= with the lower part of the inner surface of the wall,—that is,
with the keraphyllous layer of the wall. This =white line= (Figs. 31,
_g_, and 35, _h_), of so much importance to the horseshoer, is formed
by the horn-leaves, and by those short plugs of tubular horn which
are secreted by the villi that are always found at the lower ends of
the fleshy leaves. The white line may be said to exist wherever the
horn-leaves can be discerned upon the plantar surface of the hoof.
It not only passes around the circumference of the sole from heel
to heel, but may be followed forward from the buttresses along the
bars almost to the summit of the frog. The horn of the white line is
soft, unpigmented (white), and possesses so very little resistance
(strength) that it is often found crumbling or even absent in places.
The visible part of the white line is usually of a grayish-black color,
owing to the working in from below of dirt and liquid manure, and to
staining by rust from the nails. =The white line is very important,
since it serves as the point from which we judge of the thickness of
the wall, and because the horseshoe nail should penetrate it.=
[Illustration: FIG. 39.
A horny frog cut vertically and lengthwise through its middle: _a_,
upper surface; _b_, frog-stay; _c_, median lacuna of frog, which at
_c′_, is overlaid with superposed layers of horn.]
[Illustration: FIG. 40.
Longitudinal section of the wall magnified. The dark stripes parallel
and close together are horn-tubes; the lighter surface between the
tubes represents the intertubular horn. Notice that the horn-tubes are
of various diameters. The space between _a_ and _b_ represents the
small tubes of the outer, darker horn of the principal (middle) layer
of the wall; the space between _b_ and _c_ the lighter, inner horn of
the wall; _c_, _d_, the horn separating the wall proper from the horny
leaves; _d_, _e_, the horny leaves (keraphyllous tissue), on which can
be seen fine, parallel, vertical stripes; in the horn-leaf at _f_,
_f′_, are seen fissures passing obliquely upward and outward towards
the wall.]
=The Frog= (Figs. 31, _h_, 35, _k_, _l_, 38 and 39), secreted by the
velvety tissue covering the plantar cushion and presenting almost the
same form as the latter, lies as a wedge between the bars and between
the edges of the sole just in front of the bars, with both of which
structures it is intimately united. Its horn is _quite soft_ and _very
elastic_. The median lacuna or cleft of the frog (Fig. 31, _l_)
divides it into two branches (Fig. 31, _i_), which pass backward and
outward into the horny bulbs (Fig. 31, _k_). In front of the median
lacuna the two branches unite to form the _body_ of the frog (Fig. 31,
_h_), which ends in a point, designated the _point_, apex, or summit of
the frog. On the upper surface of the frog, directly over the median
cleft of the lower surface, there is a small projection called the
frog-stay (Figs. 35, _l_, 38 and 39, _b_), which fits into the median
cleft of the plantar cushion. Besides, the upper surface of the frog
shows many minute openings, similar to but smaller than those of the
sole and coronary groove, for the reception of villi. In unshod hoofs
the frog, sole, bars, and bearing-edge of the wall are on a level; that
is, the plantar surface of such hoofs is perfectly flat.
[Illustration: FIG. 41.
Cross-section of the wall, magnified: _a_, horn-tubes; _b_,
intertubular horn.]
The _minute structure of the horn_ can scarcely be considered in detail
in an elementary treatise such as this is. However, a few of the most
important facts are as follows:
If we carefully examine a transverse section of the horn of the wall
(Fig. 41), sole, or frog, we will see with the naked eye, though much
better with a magnifying glass, many minute points quite close to one
another, and greatly resembling the small openings which we have seen
in the coronary groove of the wall and on the upper surface of the
horny sole and frog. If, now, we examine a longitudinal section of the
wall (Fig. 40) or sole, we will see a number of fine, dark stripes
which are straight, parallel, quite close to one another, of different
widths, and which are separated by bands of lighter horn also of
different widths. A thin section or slice of the wall taken at right
angles to the direction of these dark lines (Fig. 41) shows us that the
minute points that are visible to the naked eye, when held up to the
light or moderately magnified, prove to be small openings (Fig. 41,
_a_). Since these openings, shown in Fig. 41, represent the dark lines
shown in Fig. 40, because an opening is found wherever there is a dark
line, _we must regard all dark lines seen in longitudinal sections of
wall, sole, and frog as hollow cylinders or tubes_, though they are not
always hollow, but are often filled with loosely adjusted, crumbling,
broken down horn-cells. The dark edges of the openings (_a_) consist of
thick layers of horn-cells (tube-walls). The entire structure is called
a =horn-tube=, and the lighter-colored masses of horn (Fig. 41, _b_)
between the tubes are known as =intertubular horn=.
=With the exception of the horny leaves of the wall
and bars, all the horn of the hoof is composed of
horn-tubes and intertubular horn.=
The horn-tubes of the wall, sole, and frog always run downward and
forward parallel to the direction of the wall at the toe,—that is,
in a direction parallel with the inclination of the hoof as a whole.
Although the wall, sole, and frog differ from one another considerably
with respect to the size and number of the horn-tubes, the quality
of the intertubular horn, and the thickness and strength of the
horn-cells, these differences are only of subordinate interest or
importance to the horseshoer; but he who desires to learn more of this
matter is referred to the work of Leisering & Hartmann, “Der Fuss des
Pferdes in Rücksicht auf Bau, Verrichtungen und Hufbeschlag,” eighth
edition, Dresden, 1893. This book also treats of the variations in the
quality of hoofs, which is very important for the practical horseshoer
to know. It, furthermore, considers the solidity and strength of the
horn of the different parts of the hoof.
With respect to solidity, two kinds of horn are distinguished,—namely,
=hard= and =soft horn=. The periople, the white line, and the frog are
soft horn structures; the middle layer of the wall and the sole are
hard or solid horn. The wall, however, is somewhat harder and more
tenacious than the sole, for the latter passes off in more or less
large flakes (exfoliates) or crumbles away on its lower surface, at
least in shod feet, while no such spontaneous shortening occurs in the
wall.
[Illustration: FIG. 42.
Vertical section through middle of a forefoot, the skin and pododerm
being in red. (In the figure the direction of both long and short
pasterns, _B_ and _D_, is too nearly vertical—too steep). _A_,
metacarpal bone (cannon); _B_, os suffraginis (long pastern);
_C_, inner sesamoid bone (to render it visible a portion of the
intersesamoid ligament was removed); _D_, os coronæ (short pastern);
_E_, os pedis (foot-bone); _F_, navicular bone; _a_, extensor tendon;
_b_, suspensory ligament of the fetlock; _b′_, superficial inferior
sesamoid ligament; _c_, perforatus tendon or flexor of the os coronæ;
_c′_, ring passing forward from this tendon and encircling the
perforans tendon; _d_, perforans tendon; _e_, capsular ligament of
fetlock-joint; _f_, capsular ligament of coronary joint; _g_, _g′_,
capsular ligament of pedal joint; _h_, synovial sheath of the perforans
tendon; _i_, plantar cushion and fleshy frog; _i′_, bulbs or glomes
of plantar cushion; _i″_, indicates the lowest point reached by the
plantar cushion, which in the figure is hidden below by the frog-stay
of the horny frog; _k_, coronary band (red); _l_, podophyllous tissue
(red); _m_, velvety tissue of the sole (red); _n_, velvety tissue of
fleshy frog (red); _o_, wall; _p_, sole; _q_, frog; _q′_, the inner
half of the frog-stay which reposes in the median lacuna of the fleshy
frog; _s_, hair-skin (red).]
Soft horn differs from hard horn in that its horn-cells never become
hard and horn-like. It is very elastic, absorbs water quickly, and as
readily dries out and becomes very hard and brittle and easily fissured
and chapped. With respect to _quality_, we distinguish good and bad
horn; the former is fine and tenacious (tough), the latter coarse and
either soft and crumbling or hard and brittle. If not dried out, all
horn is elastic, though soft horn is more elastic than hard. All horn
is a _poor conductor of heat_.
The relative positions of the various parts of the foot are shown in
Fig. 42.
Fig. 43 represents the exterior of a well-formed foot.
[Illustration: FIG. 43.
Right forefoot viewed from the side: _A_, lower end of the cannon; _B_,
fetlock-joint; _C_, long pastern; _D_, coronet; _E_, hoof; _F_, heel;
_F′_ inner heel; _G_, foot-lock covering the ergot.]
CHAPTER II.
THE FOOT IN ITS RELATION TO THE ENTIRE LIMB.
[Illustration: FIG. 44.
Normal (regular) position of fore-limbs.]
As there are well-formed and badly formed bodies, so there are
well-formed and badly formed limbs and hoofs. The form of the hoof
depends upon the position of the limb. A straight limb of normal
direction possesses, as a rule, a regular hoof, while an oblique or
crooked limb is accompanied by an irregular or oblique hoof. Hence,
it is necessary, before discussing the various forms of the hoof, to
consider briefly the various positions that may be assumed by the
limbs. In this discussion we shall deal with the =living= horse.
A. Standing Positions of the Limbs.
The position of a limb depends upon the varying lengths of its
component bones and the angles at which they meet one another. To judge
the standing position of a fore-limb one must stand _in front_ of the
horse; to judge a hind limb, stand _behind_ the horse; the backward
or forward deviations of both front and hind limbs are judged by
standing at the side. But a horse does not always move as his standing
position would lead one to suspect; standing and moving are different.
Therefore, in order to arrive at a proper judgment, one must observe
the limbs both at rest and in motion.
(_a_) =The position of a limb viewed from in front= is normal or
straight (Fig. 44) when it stands vertical or perpendicular. A
plumb-line dropped from the point of the shoulder (middle of the
scapulo-humeral articulation) should pass down the middle line of the
limb, dividing it into inner and outer halves of equal width, and
meeting the ground at the middle of the toe.
[Illustration: FIG. 45. Base-wide]
[Illustration: FIG. 46. Toe-wide]
[Illustration: FIG. 47. Toe-narrow (“pigeon-toed”)]
In the _base-wide standing position_ (Fig. 45) the plumb-line falls to
the inner side of the limb; the limb extends obliquely downward and
outward. To this class belong also the _knee-narrow_ (knock-kneed)
_position_, in which the knees are too close together, while the feet
stand wide apart, and the _toe-wide position_ (splay-footed, Fig. 46)
in which the toes point obliquely forward and outward. In base-wide
positions either the entire limb extends downward and outward or the
foot alone is turned outward.
The _base-narrow position_ is frequently observed in horses with
very wide breasts. The limbs run downward and inward, a plumb-line
dropped from the point of the shoulder falling to the outer side of
the leg and foot. A special form of the base-narrow position is the
_toe-narrow_ or _pigeon-toed position_ (Fig. 47). In some instances the
legs are straight and perpendicular down to the fetlock, while from
there to the ground the phalanges incline obliquely inward. Another
form is the _knee-wide_ or _bandy-legged position_, in which the knees
are placed too far apart, while the cannons and phalanges incline
downward and inward.
[Illustration: FIG. 48. Normal (regular) fore-limb in profile.]
[Illustration: FIG. 49. Normal (regular) hind-limb in profile.]
[Illustration: FIG. 50. Camped in front.]
[Illustration: FIG. 51. Calf-kneed.]
[Illustration: FIG. 52. Acute-angled foot (low-jointed).]
=The position of a fore-limb viewed in profile= is regular or normal
(Fig. 48) when a perpendicular line dropped from the tuberosity of
the acromian spine (point of union of the upper and middle thirds of
the scapula or shoulder-blade) divides the leg from the elbow to the
fetlock into anterior and posterior halves of equal width, and touches
the ground immediately back of the bulbs of the heel. A perpendicular
line dropped from the point of union of the middle and lower thirds of
the scapula (shoulder-blade) will cut the humerus into halves, and meet
the ground between the toe and the heel.[2] The _foot-axis_ (line of
direction of the three phalanges) and the wall at the toe form an angle
of from forty-five to fifty degrees with the horizontal ground-surface.
[2] =In station of rest=, the normal position of a fore-leg, as seen
from the side, is somewhat different. The _station of rest_ is the
position that is maintained with the least possible muscular effort.
With gradual muscular relaxation the head and neck sink to a point
somewhat below the line of the back, the top of the shoulder-blade
sinks a little, and the shoulder and elbow joints move forward till
the centre of the elbow joint is directly above the ground-surface of
the hoof. Therefore, when a horse _at rest_ stands firmly on all four
feet, _the fore-leg_ viewed from the side, _has a normal_ (regular)
_direction, when a perpendicular line dropped from the tuberosity of
the acromian spine passes through the middle of the elbow joint and
meets the ground near the middle of the hoof_.
From this normal or regular standing position, there are _deviations
forward_ as well as _backward_.
=Forward Deviations.=—“_Standing in front_” or “_camped in front_”
(Fig. 50) is that position in which the entire leg from the body to
the ground is placed too far forward. _Sheep-kneed_ (Fig. 51) is that
position in which the forward deviation is from the knee downward,
the knee being placed too far under the body. “_Weak-jointed_,”
“_low-jointed_,” or “_acute-angled_” (Fig. 52) is that position in
which the limbs are perpendicular and straight down as far as the
fetlock-joint, but the feet are placed too far in front.
[Illustration: FIG. 53. Standing under.]
[Illustration: FIG. 54. Knee-sprung.]
=Backward Deviations.=—_Standing under in front_ (Fig. 53) is that
deviation in which the entire leg from the elbow down is placed back
of the perpendicular line and, therefore, too far under the body.
When this deviation affects only the cannon bone, the horse stands
bent forward at the knees,—a condition known as “_goat-kneed_,”
“_buck-kneed_,” “_over in the knees_,” or, more commonly,
“_knee-sprung_” (Fig. 54). When the backward deviation is only from the
fetlock down, the animal is said to stand _upright_ or “_straight in
the fetlock_.”
[Illustration: FIG. 55. Normal (regular) position viewed from behind.]
[Illustration: FIG. 56. Base-wide (cow-hocked).]
[Illustration: FIG. 57. Base-narrow.]
[Illustration: FIG. 58. Base-narrow position of hind limbs
(bandy-legged).]
(_b_) =A hind leg viewed from behind= is said to be _regular_ or
_straight_ (Fig. 55) when a perpendicular line dropped from the
tuberosity of the ischium (see Fig. 1, 9″) divides the entire limb into
inner and outer halves of equal width and touches the ground opposite
the median lacuna of the frog. =Seen from the side=, this line just
touches the point of the hock and, passing down at some distance from
the flexor tendons, meets the ground considerably back of the heels.
A perpendicular line dropped from the hip-joint should pass through
the foot, meeting the ground half-way between the point of the toe and
the heel (Fig. 49). There are base-wide, base-narrow, toe-wide, and
toe-narrow deviations in the hind limbs as in the fore-limbs.
The hind limbs are _base-wide_ when they, either as a whole or in part,
deviate outward from the normal. The “_cow-hocked_“ position (Fig. 56)
is an example of the base-wide; in this case the points of the hocks
are too close and turn towards each other, while the feet are widely
separated and the toes turned outward. _Base-narrow_ is that position
of the hind legs in which either the entire leg deviates to the inner
side of the perpendicular (Fig. 57), or the leg is about perpendicular
down as far as the hock, but below this joint runs downward and inward
(Fig. 58). In this latter case the hocks may be too far apart, the leg
is bent outward at the hock and the animal is termed “_bandy-legged_,”
“_bow-legged_.”
=Viewing a hind limb from the side=, it may be observed to deviate
either forward or backward from the normal. Among forward deviations
is the so-called “_sabre-leg_“ or “_sickle-hock_“ (Fig. 59), in which
the hock-joint is too much flexed, the foot placed too far forward
under the body, and the fetlock too slanting. In the position known as
“_camped behind_” (Fig. 60) the leg is behind the body and the pastern
is too upright, too nearly vertical.
It is possible for each limb of the same horse to assume a different
direction. It more often happens that if the fore-limbs are base-wide
the hind limbs are base-narrow, or _vice_ _versa_. While there are some
other deviations that differ somewhat from those already described,
they are of less importance to the horseshoer.
[Illustration: FIG. 59. Sabre-legged or sickle-hocked.]
[Illustration: FIG. 60. Camped behind.]
B. Forms of Feet. Viewed from in Front, from Behind, and in Profile.
In all the various positions of the limbs we find the feet in one of
the following _three forms_, or very closely approaching one of them.
By means of a proper knowledge of these three forms, the judging of the
form, flight of the foot in travelling, and preparation of the hoof
for the shoe, as well as the choice of the length of the shoe, are
regulated, facilitated, and simplified.
Whether a horse’s feet be observed from _in front_ or from _behind_,
their form corresponds to, or at least resembles, either that of the
=regular= position (Figs. 61 and 62), the =base-wide= or toe-wide
position (Figs. 63 and 64), or the =base-narrow= or toe-narrow position
(Figs. 65 and 66).
By the _direction_ of the =foot-axis=—that is, an imaginary line
passing through the long axis of the three phalangeal bones (Figs. 61,
65, 67, 68 and 69)—we determine whether or not the hoof and pastern
stand in proper mutual relation.
[Illustration: FIG. 61.]
[Illustration: FIG. 62.
A pair of front feet of regular position viewed from in front and from
behind.]
In the regular standing position (Figs. 61 and 62) the foot-axis runs
straight downward and forward, in the base-wide position (Figs. 63 and
64) it runs obliquely downward and outward, and in the base-narrow
position (Figs. 65 and 66) it runs obliquely downward and inward.
[Illustration: FIG. 63.]
[Illustration: FIG. 64.
A pair of feet of the base-wide (toe-wide) position seen from in front
and from behind.]
_Viewing the foot from the side_, we distinguish the =regular=
(normal) position (Fig. 68), and designate all forward deviations as
=acute-angled= (long toe and low heel, Fig. 67), and all deviations
backward from the regular position as =upright= (short toe and high
heel, Fig. 69), steep-toed, or stumpy.
[Illustration: FIG. 65.]
[Illustration: FIG. 66.
A pair of feet of the base-narrow (toe-narrow) position seen from in
front and from behind.]
When the body-weight is uniformly distributed over all four limbs, the
foot-axis should be _straight_ (Figs. 67 and 69), not “broken” (bent);
=the long pastern, wall at the toe, and foot-axis should have the same
slant=.
[Illustration: FIG. 67. An acute-angled hoof.]
[Illustration: FIG. 68. A normal-angled hoof.]
[Illustration: FIG. 69. An upright (“stumpy”) hoof.]
[Illustration: FIG. 70. The “bear-foot.”]
A peculiar form of foot is the so-called _bear-foot_ (Fig. 70), in
which the foot-axis, viewed from the side, is broken strongly forward
at the coronet. The wall at the toe stands much steeper than the long
pastern and is more or less convex; in other words, a low-jointed,
sloping pastern is attached to an upright hoof. Such a foot is
sometimes improperly called a “club-foot.”
C. Lines of Flight of Hoofs in Motion.
If we observe horses moving unrestrained over level ground, we will
notice differences in the carriage of the feet. =Viewed from in front,
or from behind=, in the _regular standing position_ of the limbs the
hoofs are carried forward in a _straight direction_, that is, in a
line parallel with the median line of the body (Fig. 71). The toes
likewise point straight forward; the hoofs alight properly (flat) on
the ground. If the horse stands _base-wide_, the hoof is carried in a
circle; from its position, which is behind and well out from the median
line, the hoof passes first forward and inward until it is close to
the supporting leg, and then outward to the ground (Fig. 72), where
the shock is received principally upon the outer toe. The toes point
either directly forward, as in the regular standing position (Fig. 72),
or forward and outward as in the toe-wide position (Fig. 73). In the
toe-wide position the hoof in its flight may cross the median line.
Exactly the reverse is true of the horse that stands _base-narrow_;
in this case the hoof is moved in a circle whose convexity is
outward,—that is, the hoof from its position behind, and close to the
median line, is carried forward and outward and then inward to the
ground (Figs. 74 and 75).
=Viewed from the side=, the line of flight of a hoof is determined
largely by the obliquity (slant) of the foot-axis.
[Illustration: FIG. 71]
[Illustration: FIG. 72.]
[Illustration: FIG. 73.]
[Illustration: FIG. 74.]
[Illustration: FIG. 75.]
1. With a straight foot-axis of _normal slant_ (45°-50°, Fig. 76, _A_),
the hoof follows the arc of a circle and reaches its highest point when
directly above the supporting hoof, _i.e._, when half-way in the stride.
2. With a straight, but _acute-angled_ foot-axis (less than 45°, Fig.
76, _B_), the hoof rises rapidly, reaches its highest point before
it has completed the first half of the stride, _i.e._, before it has
passed the supporting hoof, and descending gradually in a long curve
alights easily on the ground.
3. With a straight, but upright foot-axis (55° or more, Fig. 76, _C_),
the hoof rises slowly, reaches its highest point in front of the
supporting hoof, from which point it descends rapidly. The gait is
“choppy,” and in the saddle-horse unpleasant for the rider. _The length
and the height of the stride are greatest in acute-angled feet; least
in upright feet._ Furthermore, length and height of stride are in a
measure dependent on breeding, training, condition of the legs (whether
stiffened by use or disease), length of the hoof and the weight of the
shoe.
[Illustration: FIG. 76.
Flight of the hoof as seen from the side: _A_, flight of a regular
hoof; _B_, flight of an acute-angled hoof; _C_, flight of an upright
hoof.]
Many deviations in the line of flight of hoofs and in the manner in
which they are set to the ground occur; for example, horses heavily
burdened or pulling heavy loads, and, therefore, not having free use
of their limbs, project their limbs irregularly and meet the ground
first with the toe; however, careful observation will detect the
presence of one or the other of these lines of flight of the foot.
Irregular carriage of the feet renders a horse unsuitable for general
purposes only when it is very pronounced, in which case certain
troublesome conditions, such as interfering and disease of joints, are
of frequent occurrence.
D. The Influence of Weight in the Shoe or Otherwise Attached to the
Hoof, in Altering the Flight of the Hoof.
There is nothing mysterious in the effect of weight upon the flight
of the feet. On the contrary, the lines of flight are determined (as
shown in pages 72-74, Figs. 71-76), _first_, by the relation of the
transverse axes of the hinge-joints of the leg and foot to the line of
progression (median line); _second_, by the length and obliquity of the
hoof and pastern; _third_, by the height and length of stride which is
natural to each individual.
_Weight induces higher action and a longer stride._ Inertia increases
with the weight. A heavy shoe cannot be snatched from the ground as
quickly as a light one, but when moving forward at a given velocity its
greater momentum (momentum = mass (wt) × velocity: m = wt × v) carries
the foot farther forward then does the lighter shoe. Thus, the heavier
shoe, or weight attached to the hoof, lengthens the stride at both
ends. The farther from the centre of rotation of the scapula the weight
is placed, _i.e._, the nearer to the toe it is placed, the greater the
muscular effort required to start it and to stop it.
_Height of action_, though largely the result of breeding, temperament,
and the exhilaration that accompanies perfect health and entire
absence of muscular fatigue, is to a certain extent influenced by the
_inclination of the pastern and toe to the cannon_. _The acute-angled
foot_, in the folding of the leg during the first half of the stride,
moves through a longer arc of a circle whose centre is the fetlock
joint than does the normal or the upright foot; rises more rapidly
and to a higher point. (See Fig. 76, _B_.) When the momentum of a foot
moving rapidly and abruptly upward is increased by weight the result is
extreme and even exaggerated flexion of all joints of the leg, and by
allowing the hoof to grow long the flexion is still further increased.
In the show ring, harness horses with fair natural action may be made
to “climb” by shoes weighing from thirty to sixty ounces upon hoofs
an inch or more longer than normal. The leverage of a heavy shoe on
a long hoof is excessive, fatiguing and most injurious to ligament,
tendon and muscle. The action, while high, is _labored_, _pounding_ and
_altogether inelegant_.
[Illustration: FIG. 77.
A 40 oz. right front shoe (hoof-surface) to increase knee-action in a
high acting harness horse. For show-purposes only.]
[Illustration: FIG. 78.
The same seen from the ground-surface in profile: _a_, bevel from inner
border of the web to outer border; _b_, ends of the branches of full
thickness from outer to inner border.]
In the training of trotters weight is often used _to increase the
length of the stride_, or to cause a _higher folding of a front foot_,
in order to prevent “scalping“ or “speedy-cut.“ As soon as the new gait
becomes a fixed habit the weight should be gradually lessened. _Weight
is carried with less fatigue at a trot_ then at a pace, or at a gallop.
It therefore steadies a trotter that is inclined to pace, or “break”
into a run. The increased momentum of the weighted hoof makes for
rhythm of movement, and increases the difficulty of skipping, dwelling,
or mixing gaits.
In the _base-wide_ (toe-wide) and _base-narrow_ (toe-narrow) _standing
positions_, the flight of the hoofs, as seen from in front or behind,
is not straight forward, _i.e._, parallel to the line of progression
of the body, but in _arcs of circles_. (See Figs. 72-75, p. 73.) In
these cases, increasing the weight of the hoofs, by increasing the
momentum, must of necessity increase the tendency of the hoofs to move
off at a tangent to the curves which they describe. In other words,
_weight increases the centrifugal force_ of a body moving in a curve.
The _outward swing_ of the hoofs of a base-narrow horse (paddling), and
the _inward swing_ of a base-wide horse (interfering), are made _more
pronounced by adding weight to any part of the hoof_. _The centrifugal
force is greatest_ in base-wide feet when the weight is on the medial,
or inner side of the hoof; in base-narrow feet when it is on the
lateral or outer side.
A side weight, or side weight shoe is often of service in a cross
firing pacer. This animal usually stands base-narrow (toe-narrow)
behind, and in motion his hind hoofs describe a curve at first forward
and outward and then inward till contact is made with the diagonal hoof
or leg. The added weight (placed on the outer side) by increasing the
centrifugal force carries the hoof just enough farther from the centre
around which the hoof swings to prevent contact. (See cross-firing, p.
138.)
Finally, it must not be forgotten that _weight is always weight_; that
it _cuts speed_ and _devours endurance_.
E. Forms of Hoofs.
_A front hoof of the regular standing position_ (Fig. 79). The inner
and outer walls differ but little in direction and thickness. The outer
wall is a little thicker and somewhat more slanting than the inner (see
Figs. 61 and 62), and its outer circumference describes a larger arc of
a circle,—that is, is more curved, as can be seen both at its plantar
border and at the coronet. The length of the quarter in relation to the
length or height of the side wall and toe is about as 1: 2: 3. The toe
forms an angle with the ground of forty-five to fifty degrees (see Fig.
68). The direction of the wall at the toe, viewed from the side, should
be parallel with the direction of the long pastern.
[Illustration: FIG. 79.
Right fore-hoof of the regular position: _a_, side wall; _b_, quarter;
_c_, beginning of the bar; _d_, buttress; _e_, middle of the bar;
_f_, body of the sole; _f′_, branches of sole; _g_, white line; _g′_,
apparent end of the bar; _h_, body of the frog; _i_, branch of the
frog; _k_, bulbs (glomes) of the heel; _l_, middle cleft of frog; _m_,
lateral cleft of frog.]
_A hoof of the base-wide position_ (Fig. 80) _is always awry_, because
the outer wall is naturally somewhat longer and decidedly more slanting
then the inner (see Figs. 63 and 64). The plantar border of the outer
wall describes a large arc, whose sharpest curvature is where the side
wall passes into the quarter. The plantar border of the inner wall is
straighter (less curved); the outer half of the ground-surface (sole)
of the hoof is, therefore, wider than the inner. So long as the hoof
is healthy, both branches of the frog are equally developed. The
wryness of the hoof depends upon the direction of the limb; therefore,
a base-wide hoof should be regarded as a _normally wry hoof_, to
distinguish it from hoofs which are wry from disease.
_A hoof of the toe-wide position_ (Fig. 81) is distinguished from the
preceding by the bending or curvature of the plantar border of the
outer toe and inner quarter being often decidedly less pronounced than
on the inner toe and outer quarter; therefore, two short curves and two
long curves lie opposite each other; in other words, the inner toe and
outer quarter, lying opposite each other, are sharply curved, while the
outer toe and inner quarter, lying opposite each other, are much less
sharply bent or curved. The toes are turned out. The feet are not set
down flat upon the ground, but meet it with the outer toe.
[Illustration: FIG. 80. Right fore-hoof of the base-wide position.]
[Illustration: FIG. 81. Right fore-hoof of the toe-wide position.]
_A hoof of the base-narrow position is normally wry_, but never so
pronounced as a hoof of the base-wide position. The inner wall is
but little, more oblique than the outer, the difference being most
noticeable at the quarters (Figs. 65 and 66). The curve of the plantar
border of the wall is similar to that of a regular hoof, except that
the inner side wall and quarter are a little more sharply curved in a
base-narrow hoof. Occasionally the outer quarter is somewhat drawn in
under the foot.
This form of hoof is most distinctly marked in animals that stand
toe-narrow or are bandy-legged.
As to the _forms of the hind hoofs_, what has been said concerning the
influence of position of the limbs upon the shape of the front feet
will apply equally well to them. The hind hoof (Fig. 82) is not round
at the toe, but somewhat pointed or oval. It greatest width is between
the middle and posterior thirds of the sole. It usually has a strongly
concave sole and a somewhat steeper toe than the fore-hoof; viewed from
the side, the angle of the toe with the ground in the regular standing
position is from fifty to fifty-five degrees.
[Illustration: FIG. 82.
Right hind hoof of the regular position: _a_, side wall; _b_, beginning
of the quarter; _c_, beginning of the bar; _d_, buttress; _e_, middle
of bar; _f_, body of the sole; _f′_, branch of sole; _g_, white line
of the toe; _g′_, white line of the bar; _h_, body of the frog; _i_,
branch of the frog; _k_, bulbs of heel; _l_, middle cleft of frog; _m_,
lateral cleft of frog.]
Finally, we also distinguish _wide_ and _narrow_ hoofs; they are
not dependent upon the position of the limbs, but upon the race and
breeding of the animal.
_The wide hoof_ (Fig. 83) is almost round upon its plantar surface.
Its wall runs quite oblique to the ground. The sole is but moderately
concave, and the frog is strong and well developed. _The narrow hoof_
(Fig. 84) is rather elliptical, with steep side walls, strongly concaved
sole, and small, undeveloped frog. The horn of the narrow hoof is fine
and tough; of the wide hoof, usually coarse. The wide hoof may readily
become flat. Narrow hoofs are either the result of breeding or premature
shoeing.
In enumerating the preceding forms of the hoof we have by no means
referred to all the forms in which the hoof may be found; on the
contrary, hoofs vary in shape and quality to such an extent that among
a hundred horses no two hoofs can be found which are exactly alike. In
fact, the same variety exists as in the faces of people, and we know
that we can recall in succession even many more faces without finding
two that are exactly alike. This explains the manifold differences in
horse’s shoes with respect to size, form and other qualities.
[Illustration: FIG. 83. Wide fore-hoof.]
[Illustration: FIG. 84. Narrow fore-hoof.]
Suppose now a hoof is before us; it is first necessary to know whether
or not it is =healthy=. Unfortunately, a perfectly healthy hoof is
not so easy to find as one may think. We recognize a sound hoof by
the following marks: Seen from in front or from the side, the course
of the wall from the coronet to the ground, in the direction of the
horn-tubes, is straight,—that is, bent neither in nor out. A straight
edge, placed upon the wall in the direction of the horn-tubes, touches
at every point. The wall must show neither longitudinal nor transverse
cracks or fissures. If there be rings, their position and course are
important. Rings which pass around the entire circumference of the
wall parallel to the coronet indicate nothing more than disturbances
of nutrition of the hoof; _but the hoof cannot pass for sound_
when the rings have any other position and direction than the one
mentioned, or if the rings upon any part of the wall are more marked
than elsewhere, even though they may be parallel to the coronary band.
Marked ring-building upon the hoofs of horses which have regular
feeding, grooming, and work indicates a weak hoof. Viewed from the
ground-surface and from behind, the bulbs of the heels should be well
rounded, strongly developed, and not displaced. The concave sole should
show no separation along the white line. The frog should be strong,
well developed, and have symmetrical branches and a broad, shallow, dry
median lacuna. The lateral lacunæ of the frog should be clean and not
too narrow. The bars should pass in a straight direction forward and
inward towards the point of the frog. Any bending outward of the bars
towards the branches of the sole indicates the beginning of a narrowing
of the space occupied by the frog,—that is, contraction of the heels.
The horn of the branches of the sole in the buttresses and in their
proximity should show no red staining. The lateral cartilages should be
elastic. No part of the foot should be weakened at the cost of other
parts. By firm union of all strong parts the strength and vigor of the
hoof is in no sense disturbed. _If one desires to ascertain the exact
form and state of health of the hoof, it must never be inspected and
judged alone, but in connection with the entire limb._
F. Growth of the Hoof and Wear of the Hoof and Shoe.
All parts of the horn of the hoof grow downward and forward, the
material for this growth being furnished by the remarkably large
quantity of blood which flows to the pododerm. The growth of the hoof
is regulated by the nerves.
As a rule, the hoof grows =uniformly=,—that is, one section of the wall
grows just as rapidly as another. A visible indication of growth is the
increase in height and width of the hoof from colthood to maturity.
The _rapidity of growth_ of the wall varies, amounting in a month to
from one-sixth to one-half of an inch. The average monthly growth in
both shod and unshod horses of both sexes is, according to my own
experiments, one-third of an inch. Hind hoofs grow faster than front
hoofs, and unshod faster than shod. The hoofs of stallions grow more
slowly than those of mares and geldings.
Abundant =exercise=, proper grooming (flexibility and moistness of
the horn), regular dressing of the wall, and =running barefoot= from
time to time =favor growth=; while little or no exercise, dryness, and
excessive length of the hoof hinder growth.
The time required for the horn to grow from the coronet to the ground
is, therefore, equally variable, and is, moreover, dependent upon the
height (length of toe) of the hoof. At the toe the horn grows down in
from eleven to thirteen months, at the mammæ or sides in from six to
eight months, and at the quarters in from three to five months. The
time required for the renewal of the entire hoof we term the _period of
hoof renewal_. If, for example, we know exactly the rapidity of horn
growth in a given case, we can estimate without difficulty the length
of the “period of hoof renewal,” as well for the entire hoof as for
each individual section of the wall. The duration of many diseases of
the hoof (cracks, clefts, partial bendings of the wall, contractions,
etc.) can be foretold with relative certainty only by knowing the
period of hoof renewal.
_Irregular growth_ sometimes takes place. The chief cause of this is
usually an improper distribution of the body-weight over the hoof,—that
is, an unbalanced foot. Wry hoofs of faulty positions of the limbs are
often exposed to this evil; a faulty preparation of the hoof (dressing)
for the shoe, as well as neglect of the colt’s hoofs, is in the
majority of cases directly responsible for this condition.
If in the shortening of the wall a part is from ignorance left too
long, or one-half of the hoof shortened too much in relation to the
other half, the foot will be unbalanced. The horse will then touch the
ground first with the section of wall which has been left too high,
and will continue to do so until this long section has been reduced to
its proper level (length) by the increased wear which will take place
at this point. In unshod hoofs this levelling process takes place
rapidly; such, however, is not the case in shod hoofs, for here the
shoe prevents rapid wear, and, indeed this levelling process is often
rendered impossible through the welding of high steel calks to the
shoe. If this fault in trimming be repeated at the next and subsequent
shoeings, and if the faulty relation of the ground-surface of the hoof
to the direction of the foot-axis remain during several months, the
portion of wall left too high will grow more rapidly, the walls will
lose their natural straight direction and become bent. If, for example,
the outer wall has been left too long during a considerable period of
time, a crooked hoof results (Fig. 85) in which the rings are placed
closer together upon the low (concave) side than upon the high (convex)
side. If for a long time the toe is excessively long, it will become
bent; or if this fault affects excessively high quarters they will
contract either just under the coronary band or will curl forward and
inward at their lower borders. These examples are sufficient to show
both the importance of the manner in which a horse places his foot to
the ground and its influence upon the loading, growth, and form of the
hoof.
[Illustration: FIG. 85.
Crooked (right) fore-hoof.]
Wear of the Shoe and of the Hoof upon the Shoe.
The wear of the shoe is caused much less by the weight of the animal’s
body than by the rubbing which takes place between the shoe and the
earth whenever the foot is placed to the ground and lifted.
The wear of the shoe which occurs when the foot is placed on the ground
is termed “=grounding wear=,” and that which occurs while the foot is
being lifted from the ground is termed “=swinging-off wear=.“ When a
horse travels normally, both kinds of wear are nearly alike, but are
very distinct when the paces are abnormal, especially when there is
faulty direction of the limbs. While in the majority of horses whose
limbs have been stiffened by age and overwork both kinds of wear are
most marked at the toe of the shoe, we see relatively fewer cases of
“grounding wear” at the ends of the branches (as in laminitis); on the
contrary, we =always= notice “swinging-off wear” at the toe of the
shoe. It is worthy of notice that length of stride has much to do with
the wear. We observe that with shortening of the stride both kinds of
wear occur at the toe of the shoe, and this is rapidly worn away, as
is the case with horses which are fretful and prance under the rider,
draw heavy loads, or from any other cause, as disease or infirmity, are
obliged to shorten their steps. With increase of length of stride the
wear of the shoe becomes more uniform.
[Illustration: FIG. 86.
A normal-angled foot with straight foot-axis. The shoe shows uniform
wear.]
[Illustration: FIG. 87.
An upright foot with foot-axis broken forward by reason of too high
quarters. The shoe shows “grounding“ wear at ends of branches, and
“swinging-off“ wear at toe.]
[Illustration: FIG. 88.
A hoof with foot-axis broken backward by reason of surplus horn at the
toe. The shoe shows excessive “grounding“ and “swinging-off” wear at
the toe.]
The _position_ and _form of the shoe_ have a marked influence upon its
wear; =at the place where the shoe is too far under the hoof= either
as a result of shifting or of having been nailed on crooked, or where
the outer branch has not the necessary width, or does not form a
sufficiently large curve, =the wear will be increased=.
Also the relative length of side walls, or of toe and heels, influences
rapidity of wear of the shoe. If through ignorance or carelessness one
side wall be left too long, the branch beneath will meet the ground
before other parts of the shoe and will wear faster (see Figs. 87, 88
and 89).
_The wear of the hoof upon the shoe_ occurs as a result of the
movements of the quarters. Visible indications of this are the brightly
polished, often sunken places upon the bearing-surface of the ends
of the branches, showing that scouring occurs between the horn and
the iron. Shoes which show brightly polished places in their anterior
halves have been loose. The wear of the quarters upon the shoe is not
always uniform, but is usually greater on the inner than on the outer
quarter, especially in base-wide feet. The degree of this wear of the
hoof may be from nothing to one-fourth of an inch or more from one
shoeing to the next. Finally, we should remember that this usually
invisible scouring away of the hoof gradually causes the nails at the
quarters to become loose, and that this is more clearly marked in the
front than in the hind hoofs.
G. Physiological Movements of the Hoof. (Mechanism of the Hoof.)
These movements comprise all those changes of position within and of
the hoof which are brought about by alternately weighting and relieving
the foot, and which are manifest as changes of form of the hoof. The
following changes in form of the hoof are most marked at the time
that the hoof bears greatest weight,—that is, _simultaneous_ with the
greatest descent of the fetlock-joint.
1. A lateral expansion over the entire region of the
quarters, occurring simultaneously at the coronary
and plantar borders. This expansion is small, and in
general varies between one-fiftieth and one-twelfth
of an inch.
2. A narrowing of the anterior half of the hoof
measured at the coronary border.
3. A decrease in height of the hoof, with a slight
sinking of the heels.
4. A flattening (sinking) of the sole, especially in
its branches.
These changes of form are much more pronounced in the half of the hoof
that bears the greater weight.
[Illustration: FIG. 89.
Transverse vertical section through the middle of a right fore shod
hoof of base-wide form, viewed from behind. The outer wall having been
insufficiently lowered has caused increased wear of the underlying
branch of the shoe: _a_, wear of inner branch (beneath the relatively
short wall); _b_, greater wear of outer branch beneath the relatively
long wall; _c_, the horn between the dotted line and the shoe
represents the surplus length of this outer wall.]
A hoof while supporting the body-weight has a different form, and
the tissues enclosed within it a different position, than when not
bearing weight. Since loading and unloading of the foot are continually
alternating, the relations of internal pressure even in the standing
animal are continuously changing, so that, strictly speaking, the hoof
is never at rest.
The changes in form take place in the following order: the body-weight
falls from above upon the os coronæ, os pedis, and navicular bone, and
at the moment that the foot is placed upon the ground is transmitted
through the sensitive laminæ and horny laminæ to the wall. At the
instant that the fetlock reaches its lowest point the os pedis bears
the greatest weight. Under the body-weight the latter yields, and with
the navicular bone sinks downward and backward. At the same time the
upper posterior portion of the os coronæ (Fig. 90, _A_) passes backward
and downward between the lateral cartilages (_a_), which project above
the upper border of the wall, and presses the perforans tendon down
upon the plantar cushion. The plantar cushion being compressed from
above, and being unable to expand downward, is correspondingly squeezed
out towards the sides and crowded against the lateral cartilages, and
they, yielding, press against and push before them the wall at the
quarters. The resistance of the earth acts upon the plantar surface
of the hoof, and especially upon the frog, and it, widening, crowds
the bars apart, and in this manner contributes to the expansion of the
quarters, especially at their plantar border (see Fig. 90). The horny
sole under the descent and pressure of the os pedis sinks a little—that
is, the arch of the sole becomes somewhat flattened. All these changes
are much more marked upon _sound unshod_ hoofs, because in them the
resistance of the earth upon the sole and frog is pronounced and
complete. These changes in form are more marked in front feet than in
hind. In defective and diseased hoofs it may happen that at the moment
of greatest weight-bearing, instead of an expansion a contraction may
occur at the plantar border of the quarters.
[Illustration: FIG. 90.
Vertical, transverse section of a foot seen from behind: _A_, os
coronæ; _B_, os navicularis; _C_, os pedis; _a_, lateral cartilage;
_b_, anterior portion of fleshy frog; _c_, section of perforans tendon;
_d_, suspensory ligament of the navicular bone; _l_, wall; _m_, sole;
_n_, white line; _o_, frog.]
Three highly elastic organs there are which play the chief part in
these movements,—namely, the lateral cartilages, the plantar cushion,
and the horny frog. Besides these structures, indeed, all the remaining
parts of the horn capsule, especially its coronary border, possess more
or less elasticity, and contribute to the above-mentioned changes of
form.
In order to maintain the elastic tissues of the foot in their proper
activity, regular and _abundant exercise_, with protection against
drying out of the hoof, are absolutely necessary, because the movements
of the different structures within the foot and the changes of form
that occur at each step are indispensable in preserving the health of
the hoof. Long-continued rest in the stable, drying out of the hoof,
and shoeing decrease or alter the physiological movements of the foot,
and these lead under certain conditions to foot diseases, with which
the majority of horse owners are entirely unacquainted.
As an outward, visible indication of the mobility of the quarters upon
the shoe we may point to the conspicuous, brightly polished, and often
sunken spots, or grooves, upon the ends of the branches. They are
produced partly by an in-and-out motion of the walls at the quarters,
and partly by a forward and backward gliding of the quarters upon the
shoe.
_The benefits of these physiological movements_ within the hoof are
manifold:
1. Through them shock is dispersed and the body
protected from the evil consequences of concussion
or shock.
2. These movements increase the elasticity of the
entire limb, and in this way contribute much to
a light and elegant gait.
3. They maintain a lively circulation of blood in the
vessels of the pododerm, and this insures a rapid
growth of horn.
Since it is a generally accepted fact that shoeing interferes with
the physiological movements of the hoof, alters them, indeed, almost
suppresses them, and that all these movements are spontaneous and
natural only in sound _unshod_ hoofs, we are justified in regarding
shoeing as a _necessary evil_. However, it is indispensable if we
wish to render horses serviceable upon hard artificial roads. If, in
shoeing, consideration be given to the structure and functions of the
hoof, and particularly to the hoof-surface of the shoe, the ends of the
branches being provided with a smooth, level bearing-surface, which
allows free play to the elastic horn capsule, in so far as this is not
hindered by the nails we need have no fear of subsequent disease of the
hoofs, provided the horse is used with reason and receives proper care.
PART II.
CHAPTER III.
SHOEING HEALTHY HOOFS.
A. Examination of a Horse Preliminary to Shoeing.
An examination should be made while the animal is =at rest=, and
afterwards while =in motion=. The object of the examination is to gain
accurate knowledge of the direction and movements of the limbs, of the
form and character of the feet and hoofs, of the manner in which the
foot reaches and leaves the ground, of the form, length, position, and
wear of the shoe, and distribution of the nail-holes, in order that
at the next and subsequent shoeings all ascertained peculiarities of
hoof-form may be kept in mind and all discovered faults of shoeing
corrected.
The examination is best conducted in the following order: The horse
should first be led at a walk in a straight line from the observer over
as level a surface as possible, then turned about and brought back,
that the examiner may notice the direction of the limbs and the manner
in which the hoofs are moved and set to the ground. While the animal
is moving away the observer notices particularly the hind limbs, and
as it comes towards him he examines the fore-limbs. Then a few steps
at a trot will not only show whether or not the animal is lame, but
will often remove all doubt in those cases in which, while the animal
was walking, the examiner was unable to make up his mind as to which
was the predominating position of the limb. The problem presented is,
therefore, to determine whether or not the direction of the limbs,
the lines of flight of the hoofs, and the manner in which they are
set down and picked up are regular. If there are deviations from the
normal they will fall either into the base-wide and toe-wide group
or into the base-narrow and toe-narrow group. When clear upon these
points the horse is allowed to stand quietly, and the observer, placing
himself in front, examines the foot more closely, fixes the direction
of the foot-axis clearly in his mind, marks also the form and character
of the hoofs and the position of the coronets, as far as these parts
can be inspected from in front. At the same time each hoof should be
closely inspected to determine whether the slant of both quarters
corresponds to the direction of the long pastern, and whether the
course of the wall from the coronet to the plantar border is straight
or bent in or out (contraction, fulness). Walls curved from above to
below always indicate an unnatural height of some section of the wall
and a displacement of the base of support of the foot. In order to
gain accurate and complete knowledge of the position of the limbs,
the flight of the hoofs, and the manner of setting the foot to the
ground, the horse must frequently be moved back and forth many times,
especially when the standing position is somewhat irregular and the
hoofs are of different shapes.
At this point begins the examination of the position of the limbs, and
the form of the feet and hoofs, in profile. After casting a glance over
the entire body, so as to gain an idea of the animal’s weight, height,
and length, the attention is turned to the position and direction of
the limbs and hoofs. The eye should particularly note whether the form
of the hoof corresponds to the position of the limb, and, furthermore,
whether the slant of the pastern is the same as that of the wall at the
toe,—that is, whether the foot-axis is straight or broken; also whether
the toes and quarters are parallel, for the toe is sometimes bulging
(convex) or hollowed out (concave) between the coronet and plantar
border, and the quarters are frequently contracted and drawn or shoved
under the foot (weak quarters). If the wall present rings the observer
should note their position with reference to one another and to the
coronet, and also their extent, and, furthermore, should determine
whether or not they cross one another (thrush of the frog). At the same
time he should notice the length of the shoes.
Next, the feet should be raised and the examiner should notice the
width of the hoof, the arching of the sole, the character of the frog,
the position of the bulbs of the heel, as well as the presence of any
cracks or clefts in the wall. Then the old shoes should be examined as
to their age, form, the distribution and direction of their nail-holes
(“punching”), position, and wear. With respect to the form of the
old shoe, one should observe whether or not it corresponds to the
form of the hoof. The same careful examination should be made of the
number and distribution of the nail-holes. As regards the position
of the shoe, one must first ascertain whether it completely covers
the bearing-surface of the wall, and whether the shoe extends beyond
the wall at any point and has caused interfering or given rise to
irregular wear. Finally, the wear of the shoe should be observed, and
the following points borne in mind: _One-sided wear, uneven setting
down of the feet, and an unnatural course of the wall are often found
together_, especially when uneven wearing of the shoe has existed for
a long time,—that is, during several shoeings. As a rule, in such a
case the more worn branch of the shoe is too near the centre of the
foot, and the opposite branch too far from the centre (too “full”); in
other words, the base of support (shoe) has been shifted too far in the
direction of the less worn branch. Moreover, increased wear of a part
of a shoe is an indication that the section of the wall above it is too
high (too long) (Fig. 89), or that the wall upon the opposite side of
the foot is too low (short). The twisting movement of many hind feet
should, from physiological reasons, not be hindered by shoeing.
B. Raising and Holding the Feet of the Horse to be Shod.
This can always be done without much trouble if the horse has been
accustomed to it from early colthood. Certain rules governing the
manner of taking hold of the feet, and of afterwards manipulating them,
are of value.
A shoer should =never grasp a foot suddenly=, or with both hands. The
horse should first be prepared for this act. First see that the horse
stands in such a position that he can bear his weight comfortably upon
three legs. This is well worth noticing, and if the horse does not
voluntarily assume such an easy position, move him gently until his
feet are well under his body.
If the shoer, for example, wishes to raise the left fore foot for
inspection, he stands on the left side facing the animal, speaks
quietly to him, places the palm of the right hand flat upon the
animal’s shoulder, and, at the same time, with the left hand strokes
the limb downward to the cannon and seizes the cannon _from in front_.
With the right hand he now gently presses the horse towards the
opposite side, and the foot becoming loose as the weight is shifted
upon the other leg, he lifts it from the ground. The right hand now
grasps the pastern from the inside followed by the left hand upon the
inside and the right hand on the outside; then, turning partly to the
right, the holder supports the horse’s leg upon his left leg, in which
position he should always stand as quietly and firmly as possible. If,
now, the shoer desires to have both hands free to work upon the hoof,
he grasps the toe with the left hand in such a manner that the toe
rests firmly in the palm while the four fingers are closely applied to
the wall of the toe, takes a half step toward the rear, passes the hoof
behind his left knee into his right hand which has been passed backward
between his knees to receive it, and drawing the hoof forward outward
and upward supports it firmly on his two knees,—the legs just above the
knees being applied tightly against the pastern. The forefoot should
not be raised higher than the knee (carpus), nor the hind foot higher
than the hock, nor either foot be drawn too far backward. The correct
standing position of the shoer or floorman while holding a front foot
is shown in Fig. 91. Shortness of stature (5′-5′.6″) is desirable in a
floorman.
In lifting the _left hind foot_ the animal should be gently stroked
back as far as the angle of the hip, against which the left hand is
placed for support, while the right hand strokes the limb down to the
middle of the cannon, which it grasps _from behind_. While the left
hand presses the animal’s weight over towards the right side, the right
hand loosens the foot and carries it forward and outward from the body
so that the limb is bent at the hock. The holder then turns his body
towards the right, brings his left leg against the anterior surface of
the fetlock-joint, and carries the foot backward, at which time his
left arm passes over the horse’s croup and above and to the inner side
of the hock. Finally, both hands encompass the long pastern.
[Illustration: FIG. 91. Proper position for holding a front foot.]
If the right feet are to be raised, the process is simply reversed.
In raising the feet no unnecessary pain should be inflicted by
pinching, squeezing, or lifting a limb too high. The wise shoer avoids
all unnecessary clamor and disturbance; quiet, rapid, painless methods
avail much more. In dealing with _young_ horses the feet should not be
kept lifted too long; let them down from time to time. In _old_ and
_stiff_ horses the feet should not be lifted too high, especially in
the beginning of the shoeing.
[Illustration: FIG. 92. The Martin horse rack (modified).]
_Vicious_ horses must often be severely handled. Watch the play of the
ears and eyes continually, and immediately punish every exhibition of
temper either by jerking the halter or bridle vigorously, or by loud
commands. If this does not avail, then if soft ground is at hand make
the horse back as rapidly as possible for some time over this soft
surface; it is very disagreeable and tiresome to him. To raise a hind
foot we may knot a strong, broad, soft, plaited band (side-line) into
the tail, loop it about the fetlock of the hind foot, and hold the
end. This often renders valuable service. The holder seizes the band
close to the fetlock, draws the foot forward under the body, and then
holds it as above described. The use of such a band compels the horse
to carry a part of his own weight, and at the same time hinders him
from kicking. Before attempting to place this rope or band about the
fetlock, the front foot on the same side should be raised.
The various sorts of twitches are objectionable, and their use should
not be allowed unless some painful hoof operation is to be done. The
application of the tourniquet, or “Spanish windlass,” to the hind leg
is equally objectionable.
Those horses which resist our attempts to shoe them we do not
immediately cast or place in the stocks, but first have a quiet,
trustworthy man hold them by the bridle-reins and attempt by gentle
words and soft caresses to win their attention and confidence.
_Ticklish_ horses must be taken hold of boldly, for light touches of
the hand are to such animals much more unpleasant than energetic, rough
handling. Many ticklish horses allow their feet to be raised when they
are grasped suddenly without any preparatory movements.
C. Removing the Old Shoes.
If a horse’s hoofs are healthy, all the shoes may be taken off at the
same time, but there are certain diseases of the hoof in which this
should not be done.
The rule to follow in removing every shoe is to _draw it cautiously_,
not wrench it away with violence. Hoofs which are dirty should first
be cleansed, preferably with a stiff brush. Next, the clinches should
be _carefully_ lifted by means of a rather dull clinch cutter (Fig.
93), _without injuring the horn_ of the wall. In order, now, that the
nails may be removed singly, the shoe must be slightly lifted. This may
be done in one of two ways. The shoer may use a pair of pincers (Fig.
94), with broad bills which will encompass the branch of the shoe and
come well together underneath it. The handles of the pincers are then
moved _in the direction of the branches_ of the shoe. The second method
consists in raising the branches of the shoe by driving the nail-cutter
from behind between the shoe and hoof and using it as a lever or pry to
loosen the shoe.
[Illustration: FIG. 93. Clinch cutter and punch.]
[Illustration: FIG. 94. Pincers.]
Violent and excessive twisting of the hoof and straining of ligaments
may easily occur, but the smith should guard against them by supporting
the hoof with the left hand or with the leg just above the knee, while
loosening the shoe.
D. Preparing the Hoof for the Shoe.
This preparation is usually termed paring, trimming, or dressing. It is
a most important step in the process of shoeing, and its object is to
shorten the hoof, which has grown too long under the projection of the
shoe, and prepare it to receive the new shoe. The instruments needed
for this work are the rasp and the hoof-knife (Fig. 95); upon large and
hard hoofs a pair of sharp nippers (Fig. 96), or a sharp =hewing knife,
with broad handle and perfectly flat, smooth sides=, may be used, since
these instruments will considerably facilitate and hasten the work.
[Illustration: FIG. 95. German hoof set with detachable hook blades.
(W. M. Kunde, Dresden): _a_, _a_, hoof blades; _b_, pus searcher; _c_,
scalpel.]
After the shoer has carefully examined the hoofs in the manner
described upon pages 90, 91, and 92, and has fixed in mind the relation
of the height of the hoofs to the size and weight of the body, he
cleanses the hoof and removes all stubs of old nails. At the same time
he should be asking himself _if_, _where_, and _how much_ horn is to be
removed. In all cases all loosely attached fragments of horn are to be
removed, for example, chips of horn produced by repeated bending and
stretching of the lower border of the wall. The sole is then freed from
all flakes of dead horn. The shoer then runs the rasp around the outer
border of the wall and breaks it off to the depth to which he thinks it
should be shortened, and then =cuts the wall down to its union with the
sole, so that at least one-eighth of an inch of the edge of the sole
lies in the same level as the bearing-surface of the wall=. Finally,
the wall, white line, and outer margin of the sole, forming the
“bearing-surface,” must be rasped until they are perfectly horizontal,
except that at the toe of fore-hoofs this bearing-surface may be rasped
slightly upward (rolled toe).
In dressing the hoof the =branches= of the frog should always be left
prominent enough to project beyond the bearing-surface of the quarters
about the thickness of an ordinary flat shoe. If it be weakened by
paring, it is deprived of its activity, shrinks, and the hoof becomes
narrow to a corresponding degree. The frog should, therefore, be
_trimmed_ only when it is really _too prominent_. However, loose and
diseased particles of horn may be trimmed away when it is affected with
thrush.
[Illustration: FIG 96. Nippers.]
The _bars_ should be spared and never =shortened= except when too long.
Their union with the wall at the quarters must in no case be weakened,
and never cut through (opening up the heels). They should be left as
high as the wall at the quarters, or only a little less, while the
branches of the sole should lie about one-eighth of an inch lower.
The _buttress_ (angle formed by the union of wall and bar) requires
special attention. In healthy unshod hoofs the bars run backward and
outward in a straight line from the anterior third of the frog. In shod
hoofs, however, it happens that the buttresses gradually lengthen, curl
inward, and press upon the branches of the frog, causing the latter to
shrink. In such cases the indication is to remove these prolongations
of horn from the buttresses so as to restore to the bars their normal
direction.
=The sharp edge of the plantar border of the wall should be broken
away with a rasp until the relative thickness of the wall equals its
absolute thickness.= (Fig. 97). However, in healthy hoofs, that is,
in those whose _walls are straight from the coronet to the ground_,
the outer surface of the wall should =never= _be rasped_. The only
exceptions to this rule are those cases in which there is an outward
bending of the lower edge of the wall, most frequent on the inner side
wall and quarter.
[Illustration: FIG. 97. Longitudinal (vertical) section of the wall at
the toe: _a c_ is the absolute, and _a b_ the relative thickness of the
wall. With _a_ as the centre, and the line _a c_ as a radius, a circle
is drawn; the corner of horn in front of this circle and indicated by
dotted lines is to be removed with the rasp.]
With respect to the inclination of the ground-surface of the hoof to
the direction of the foot-axis, as viewed from in front, the following
facts are established:
In the _regular_ standing position of the limbs (seen from in front)
the plantar surface of a hoof is at right angles to the foot-axis, and
the outer and inner walls are of equal heights.
In the _base-wide_ position of the limbs the plantar hoof-surface is
more or less inclined to the foot-axis, usually to a very small degree,
and the outer wall is somewhat higher (longer) and more slanting than
the inner.
In the _base-narrow_ position of the limbs the plantar hoof-surface is
more or less inclined to the direction of the foot-axis, usually quite
considerably, and the inner wall is somewhat higher than the outer.
The foot is observed from the side in order to determine the proper
relation of the length of the toe to the height of the quarters.
[Illustration: FIG. 98. An untrimmed hoof with an excess of horn (_a_)
at the toe which breaks the foot-axis backward.]
[Illustration: FIG. 99. An untrimmed hoof with an excess of horn (_b_)
at the heels, which breaks the foot-axis forward.]
[Illustration: FIG. 100. Hoof dressed and foot-axis straightened
by removing excess of horn below dotted lines in the two preceding
illustrations.]
In this also the foot-axis is our guide. If this axis is as it should
be, the wall at the toe and the long pastern will have the =same slant=
(Figs. 67, 68 and 69). If the hoof has become too long under the
protection of the shoe, this will be shown by the foot-axis being no
longer a straight line, but broken backward at the coronet (Fig. 98);
that is, the hoof in comparison with the fetlock will be too slanting.
By shortening the toe more than the quarters this faulty relation will
be corrected (Fig. 100) and the foot restored to its proper slant. If
the quarters are too long (too high) in comparison with the length of
the toe, the foot-axis will be broken forward at the coronet (Fig. 99),
and the hoof will be too upright. By shortening the quarters more than
the toe the foot-axis may be made straight. =The plantar surface of the
hoof is therefore correct (balanced) when the horse places the foot
flat upon the ground in travelling=, and when the lines bounding the
hoof, viewed from in front, from behind, and in profile, correspond to
the direction of the three phalanges (foot-axis).
Finally, this fact should be emphasized, that in changing from flat
shoes to those with calks, or the reverse, the hoofs must first be
dressed in accordance, so that the foot axes will remain straight, and
the feet be set always flat to the ground when the new shoes are on.
Each hoof, when ready for the new shoe, should be let down and the
horse allowed to stand upon it while it is again carefully examined
and closely compared with the opposite hoof. Only after such close
inspection has proved the dressing to be faultless can the hoof be
considered as properly prepared and ready for the shoe. _The two front
hoofs and the two hind hoofs, when the legs are in the same position,
should not only be of equal size, but also in proper relation to the
size and weight of the body_.
E. Preparing the Hoof for going Barefoot.
This becomes necessary when the nature of the ground and the kind of
service required of the horse render shoeing unnecessary. However,
to go barefoot the hoof must have =plenty of horn=. After removing
the shoes the =frog should be pared down nearly to the level of the
wall=, and the sharp outer edge of the wall well =rounded off= with the
rasp, in some cases as far as the white line, otherwise large pieces
of the wall will readily break away. Hoofs with very slanting walls
must be more strongly rounded off than upright hoofs. Going barefoot
strengthens the hoofs. From time to time the condition of these
shoeless hoofs should be ascertained by inspection, and any growing
fault in shape or direction of the horn immediately corrected. It quite
frequently happens that the sharp edge of the wall must be repeatedly
rounded, especially on very oblique walls (outer half of base-wide
hoofs), and the quarters may require frequent shortening, because they
are not always worn away as fast as the horn at the toe.
F. Making Shoes.[3]
Besides good, tough iron for the shoe, we need an anvil with a round
horn and a small hole at one end, a round-headed turning-hammer, a
round sledge, a stamping hammer, a pritchel of good steel, and, if
a fullered shoe is to be made, a round fuller. Bodily activity and,
above all else, a good eye for measurement are not only desirable, but
necessary. A shoe should be made thoughtfully, but yet quickly enough
to make the most of the heat.
[3] On a shoe we distinguish an _outer_ and an _inner branch_. The
anterior portion, formed by the union of the two branches, is called
the _toe_. The upper surface, upon which the hoof rests, is called the
_hoof-surface_, and the under surface, which is in contact with the
ground, the _ground-surface_. That portion of the hoof-surface which is
in direct contact with the lower border of the wall, the white line,
and a narrow margin of the sole is termed the _bearing-surface_, and
when necessary “concaving” (seating) extends from this to the inner
border of the shoe. On the ground-surface is seen the “fullering” or
“crease.”
=The iron= of which horseshoes are made is derived from the natural
iron ore. Iron used for technical purposes is not chemically pure.
Pure iron is rather too soft, and is therefore mixed with different
substances, mostly with “carbon,” the most important ingredient of our
fuel. Of course, the iron contains a very small quantity of carbon (0.5
to 5 per cent.). When iron contains more than 2.2 per cent. of carbon
it is hard, brittle, and more easily melted, and is known as crude
iron, or raw iron, because it is derived from the raw product,—black
ore. The melted crude iron is called _cast iron_. Iron is ductile when
it contains less than 2.2 per cent. of carbon, and is then called
forge iron, or _wrought iron_. Wrought iron is fusible only at a high
temperature. Only weldable iron containing less than 1.6 per cent. of
carbon is suitable for general use. Of this iron we distinguish two
sorts,—steel and wrought iron. A larger percentage of carbon is found
in steel than in wrought iron. Steel is hard, can be tempered, and may
be called tempered wrought iron. In order to temper or harden steel,
bring it to a cherry-red heat, and then cool it suddenly by dipping it
in cold water or wet sand. The tempered steel can again be softened as
desired by heating and slowly cooling. By heating to a high temperature
in a forge wrought iron will become doughy, and may then be intimately
united (welded) with another piece at the same temperature by pressure
or hammering. This property is called weld-ability; it is of great
importance in making horseshoes. The heating of iron until it reaches
the welding stage is called getting a “heat.” The act of welding
wrought iron with steel is called “steeling.”
[Illustration: FIG. 101. Fuller.]
[Illustration: FIG. 102. Hammer-punch.]
[Illustration: FIG. 103. Pritchel.]
Regarding =the tools=, the following hints are sufficient:
The _anvil_ should have a level, smooth, flat steel face.
Likewise, the round head and flat face of both _turning-hammer_ and
_sledge_ should be smooth.
On the _fullering-hammer_ (Fig. 101) the left side is flat, the right
side convex, and the cutting edge has slightly rounded corners.
The _hardy_, _fullering-hammer_, and _cold chisel_ should be flawless
on the edge.
The _punch_ (Fig. 102), used to make the nail-holes in the shoe, has
a dull point, which should correspond in size with the head of the
horseshoe-nail and have slightly rounded corners.
The _pritchel_ (Fig. 103) should not taper to a point, but should end
in a rectangular surface whose length is twice its width, in order to
punch iron through the shoe under the blow of the hammer.
Making the Shoe.
To make a flat shoe, take the length of the hoof from the point of
the toe to the buttress and the greatest width of the hoof; these two
measurements, when added together, give the length of the bar for the
shoe. The bar should be of such width and thickness as will require the
least amount of working. For a bar-shoe or a shoe with heel-calks the
bar must be correspondingly longer.
Should we wish to preserve the exact outline of the plantar border of
the wall, we may advantageously use such a _podometer_ as is shown in
Fig. 104. This consists of a perforated sheet-iron plate one-sixteenth
to one-twelfth of an inch thick. This is laid upon the hoof, and the
outline of the wall marked upon it with chalk.
If necessary, the hoof may be set on a piece of smooth, stiff wrapping
paper or card-board, and the outline of the wall closely traced with a
lead pencil.
[Illustration: FIG. 104. Podometer.]
To make a =front shoe= (Figs. 107 and 108), heat the bar white-hot
just beyond its middle, place the head of the sledge hammer across
one end of the face of the anvil, hold the unheated end of the bar
on the head of the sledge,—the heated end resting on the face of the
anvil, and bend the bar into a half-circle with the round head of the
turning-hammer. (The outer branch of all shoes is made first; in making
pairs the right shoe is made first.) The extreme end of the heated
bar is drawn out to the desired width and thickness with the sledge.
The bent branch is then placed obliquely across the heel of the horn
of the anvil, is turned over toward the right till it rests upon an
edge, and is then bevelled diamond-shaped from the toe to the end of
the branch. [The edge in contact with the horn is the inner edge of
the right branch (outer branch) of the right shoe; the edge beaten
down by the hammer is the outer edge of the outer branch.] The branch
is then flattened on the anvil because in the bending the outer edge
has been stretched and thinned, while the iron of the inner edge has
been crowded together (back-set) and thickened. In flattening, the shoe
should be left a trifle thinner on the inner edge. The branch is again
placed over the horn, and gone over lightly with the flat head of the
turning-hammer and brought to a proper shape. It is now to be concaved
with or without the help of the sledge, or the concaving may be
omitted. The concaving should end about three-fourths of an inch from
the end of the branch. Now turn the branch and fuller it, or fuller
it first and concave afterwards. The fuller should be set in about
one-twelfth of an inch from the edge for small shoes, somewhat more for
large shoes, and led from the end of the branch towards the toe, twice
being necessary to make the fullering of sufficient depth. Next, stamp
the holes, punch them through with the pritchel, run over the surfaces,
go over the outer edge of the shoe upon the horn, and, finally, hammer
the bearing-surface smooth and horizontal. The left branch is made in
the same way, except that it is turned to the left and the fullering
carried from the toe to the heel. =Any ordinary shoe can and should be
completed in the rough in two heats.= One pair of shoes requires from
eight to fifteen minutes.
The =hind shoe= (Fig. 116) is made in like manner, but the branches are
not bent in a circle but given that form shown in Fig. 106. Concaving
is not necessary; it is sufficient merely to round the inner edge of
the web.
[Illustration: FIG. 105. The curvature of a branch of a front shoe.]
[Illustration: FIG. 106. The curvature of a branch of a hind shoe.]
Since in bending the shoe, and especially the toe of a hind shoe, the
inner edge is crowded together (back-set) and thickened to the same
extent that the outer edge is stretched and thinned, we must remember
to do away with these inequalities of thickness and strain by hammering
the shoe smooth.
Peculiarities of the Shoe.
They are dependent upon the structure, direction, and position of the
leg and hoof, as well as upon the horse’s service and the nature of the
ground. Since the shoe is an artificial base of support, and since a
proper surface of support is of the greatest importance in preserving
the soundness of the feet and legs, careful attention must be given to
this matter. Naturally shoes designed for the various forms of hoofs
must present equally great and equally numerous differences of form, as
well as other peculiarities.
=General Properties.= 1. =Form.=—A form corresponding to the shape of
the hoof is indispensable in every shoe. Front and hind and right and
left shoes should be sharply defined and easily distinguishable. _Front
shoes_ must, above all else, be circular _round cut the toe_. _Hind
shoes_, on the contrary, should be _round pointed at the toe_, yet not
too much so, but as in Fig. 116.
2. =Width.=—All shoes should be wider webbed (more covered) at the toe
than at the ends of the branches. The medium width should be about
twice the thickness of the wall.
[Illustration: FIG. 107. Right front shoe, ground-surface.]
[Illustration: FIG. 108. Right front shoe, hoof-surface: _a_,
bearing-surface; _b_, concaving, or “seating.”]
3. =Thickness.=—Each shoe should, in general terms, be so thick that
it need not be renewed under four weeks. Lungwitz found that the
average required thickness is about seven-sixteenths of an inch. Of
course, this thickness must be diminished or increased according to the
rapidity of wear of the shoe. _Shoes without calks should be of uniform
thickness_, unless there are special reasons for making them otherwise.
4. =Length.=—For draft-horses they should be long enough to reach the
bulbs of the heel, otherwise shorter, though in other respects they may
differ (see “special properties”), but should in all cases completely
cover the bearing-surface of the hoof.
5. =Surfaces.=—That part of the hoof-surface of the shoe which is in
contact with the hoof (bearing-surface of the shoe, Fig. 109, _a_)
should be horizontal and wide enough to cover the wall, the white line,
and from a twelfth to an eighth of an inch of the outer edge of the
sole. Shoes for large hoofs require a broader bearing-surface than
those for small hoofs. The concaving, or “seating” (Fig. 109, _b_),
should be made deeper or shallower, according to the nature of the
sole. _Shoes for hoofs with strongly arched_ (very concave) _soles, do
not require any concaving_ (hind hoofs, narrow fore-hoofs). _The object
of concaving is to prevent pressure of the shoe upon the horny sole
except at its margin._
[Illustration: FIG. 109. Transverse section of a branch of a front
shoe: _a_, bearing-surface; _b_, concaving; _c_, fullering, or
“crease”; _d_, nail-hole.]
The ground-surface of the shoe should be flat and _perfectly
horizontal_, except at the toe, which may be turned upward (rolled toe,
“rolling motion”).
6. =Borders.=—The _outer border_ should usually be moderately
_base-narrow_,—that is, the circumference of the ground-surface of the
shoe should be less than the circumference of its hoof-surface; in
other words, the entire outer border of the shoe should be bevelled
under the foot. Shoes made base-narrow are not so easily loosened, and
materially assist in preventing interfering. The _inner border_ should
be moderately rounded.
[Illustration: FIG. 110. (_a_) correct and (_b_) incorrect fullering.]
7. =The “Fullering”= (Fig. 109, _c_).—In depth it should be about
two-thirds the thickness of the shoe, of uniform width, and “clean.” A
fullering is not absolutely necessary, but it makes the shoe lighter
in proportion to its size, facilitates a uniform placing of the
nail-holes, renders the ground-surface somewhat rough, and, because it
is rather difficult to make, increases the workman’s skill.
[Illustration: FIG. 111. Swiss military shoe, hoof-surface.]
[Illustration: FIG. 112. Swiss military shoe, ground-surface.]
8. =Nail-Holes= (Fig. 109, _d_).—=The importance of the nail-holes=,
as regards their _character_, _number_, _distribution_, _depth_, and
_direction_, =cannot be over-estimated=, because by the nails which
are driven through them the stability of the shoe upon the hoof should
be maintained without injuring the sensitive structures, splitting the
horny wall, or immoderately interfering with the elasticity of the
foot. Each nail-hole should taper uniformly from the ground to the
hoof-surface (funnel-shaped). For a medium-weight shoe six nail-holes
are sufficient, while for all heavy shoes, especially those with
toe- and heel-calks, eight are indicated; however, it should by no
means be said that every nail-hole should contain a nail. Hind shoes
usually require one more nail-hole than front shoes, yet seldom more
than eight. In front shoes the nail-holes should be placed in the
anterior half of the shoe (Figs. 107 and 108), while in hind shoes
they are to be placed in the anterior two-thirds of the shoe (Fig.
116), and in both cases so distributed that the toe shall be without
nail-holes, except in those shoes in which it may be desirable to
omit the nail-holes in an entire branch (Fig. 153). =The depth of
the nail-holes=—that is, their distance from the outer edge of the
shoe—will depend always upon the thickness of the wall, and =should
equal the absolute= (real) =thickness of the wall= (Fig. 97). It is
evident, therefore, that all nail-holes should not be placed at the
same depth (for thickness of the wall, see p. 53).
The =direction= in which the nail-holes should pass through the shoe
depends upon the obliquity of the wall. The nail-holes around the toe,
as a rule, should incline somewhat inward, the holes at the sides less
so, while those at the quarters should be punched straight,—that is,
should pass perpendicularly through the shoe.
Both front and hind shoes for army horses in time of war and manœuvres
should be so punched that one or two nails may be placed in the
posterior half of the shoe (Figs. 111 and 112).
[Illustration: FIG. 113. Form of clips: _a_, correct; _b_, indifferent;
_c_, faulty.]
9. =Clips= (Fig. 113) are _half-circular, leaf-like ears_ drawn upward
from the outer edge of the shoe. They should be strong and without flaw
at the base, and somewhat =higher and thicker= upon hind than upon
front shoes. Their height on flat shoes should equal the thickness
of the shoe, while on shoes with leather soles, or with toe- and
heel-calks they should be somewhat higher.
According to their position we distinguish toe- and side-clips. They
secure the shoe against shifting; therefore, as a rule, every shoe
should have a toe-clip. A side-clip should always be drawn up on that
branch of the shoe which first meets the ground in locomotion.
=A Shoe with Heel-Calks.=—All shoes with heel-calks designed for
healthy hoofs should be so made and applied that they will disturb the
normal setting down of the foot as little as possible, that the wear of
the shoe will take place uniformly, and slipping be diminished. The toe
of the shoe must, therefore, be left somewhat thicker than the branches
just in front of the heel-calks. Moreover, every front shoe with
heel-calks must be relatively long, and be provided with considerable
rolling motion at the toe; that is, the shoe should be turned up at the
toe, the bending beginning near the inner edge of the web. The three-
or four-cornered, somewhat conical heel-calks with rounded corners
should not be higher than the thickness of the shoe. With reference to
the direction of the ends of the branches, we should see to it that
they do not rise excessively, but that they assume as near as possible
a horizontal direction in passing back to the heels (see Fig. 115).
[Illustration: FIG. 114. Shoe without calks, with perfectly
level hoof- and ground-surfaces, and with roll at the toe (flat,
rolling motion shoe).]
[Illustration: FIG. 115. Shoe with heel-calks for a front hoof.]
=A Shoe with Toe- and Heel-Calks.=—Such a shoe should be of uniform
thickness from end to end, and should have a toe-calk and two
heel-calks that are somewhat stronger and longer than the heel-calks
of a shoe which has no toe-calk. If to a shoe of uniform thickness, on
which the heel-calks are somewhat higher than those already described,
a piece of steel (Fig. 116, _b_) of the height of the heel-calks is
welded at the toe, we have a shoe with toe- and heel-calks. The toe-calk
should never he higher than the heel-calks. There are three principal
kinds of toe-calks,—namely:
1. _The Sharp Toe-Calk._—A bar of toe-steel of proper width and
thickness for the toe-calk is thrust with the shoe into the fire. When
the end of the bar is cherry-red in color it is withdrawn, laid across
the straight hardy, and cut nearly through at a point a calk-length
from the end. Bar and shoe are then brought to a welding heat, the
calk quickly and securely welded across the toe of the shoe, the bar
wrenched away, the calk gone over again with the hammer, when it is
immediately beaten out to a sharp edge from the anterior face, either
over the far edge of the anvil, or in a foot-vise. The posterior face
of a sharp toe-calk should be perpendicular to the ground-surface of
the shoe. Machine-made toe-calks, sharp, half-sharp and blunt, provided
with a sharp spud at one or both ends, are in general use. Their use
requires two heats, and the sharp calk is blunted in the welding.
[Illustration: FIG. 116. Right hind shoe with toe- and heel-calks: _a_,
heel-calks; _b_, toe-calk; _c_, greatest width of the base of support
(_i.e._, contact with the ground) of this shoe when _without_ toe- and
heel-calks; _d_, the greatest, and _e_, the least width of the base of
support of this shoe with calks.]
2. _The Blunt Toe-Calk._—It is a rather long rectangular piece of
toe-steel, straight, or curved to conform to the toe of the shoe.
The shoe-surface and the ground-surface of the calk are of equal
dimensions. It should be welded on in one heat.
3. _The Half-Sharp Toe-Calk_ (Coffin-Lid Toe-Calk).—It resembles the
blunt calk, except that the surface of the calk that is applied to the
shoe is somewhat broader and longer than the surface that comes in
contact with the ground. It is welded on in one heat. The first and
third kinds are most suitable for winter.
Since heel-and toe-calks raise the hoof far from the ground and
prevent all pressure upon the frog, they diminish the elasticity of
the hoof and injure it. They are injurious also to the joints, because
they furnish a base of support which is essentially smaller than that
afforded by a flat shoe (Fig. 116). However, they are indispensable for
heavy draft purposes on _slippery_ roads and in winter. Upon all other
roads and in summer they are superfluous, at least upon front hoofs,
especially as they do not wholly prevent slipping.
=Special Properties.=—The many different forms of hoofs require a great
variety of shoes. Following are the special peculiarities of each of
the chief classes of shoes.
1. _Shoe for a Regular Hoof._—Outer edge: moderately base-narrow
(bevelled under) all around. Distribution and direction of the
nail-holes: regular. Length: longer than the hoof by the thickness of
the shoe (see Figs. 121 and 122).
2. _Shoe for an Acute-Angled Hoof._—Outer edge: strongly base-narrow
around the toe, but gradually becoming perpendicular towards the ends
of the branches. Punching: regular, except that the nail-holes at the
toe must incline inward somewhat more than usual. Length: rather longer
than the preceding shoe (see Fig. 123).
3. _Shoe for an Upright_ (stumpy) _Hoof_.—Outer edge: perpendicular
at the toe; but if the hoof is very steep, then base-wide at the
toe,—_i.e._, bevelled downward and outward. Punching: last nail should
be placed just beyond the middle of the shoe. Direction of the holes:
perpendicular. Length: short; at most, one-eighth of an inch longer
than the hoof. In the case of a “bear-foot” (see Fig. 70) the shoe
should be long.
4. _Shoe for a Base-Wide Hoof._—Outer edge; the outer branch should be
moderately base-narrow,—_i.e._, bevelled downward and inward, the inner
branch perpendicular. Punching: upon the outer branch the holes should
extend well back, while upon the inner branch they are to be crowded
forward towards the toe (see Fig. 117). Length will depend upon the
obliquity of the hoof as seen in profile (see 1, 2, and 3).
5. _Shoe for a Base-Narrow Hoof._—Outer edge: the outer branch either
perpendicular or base-wide, the inner branch strongly base-narrow.
Punching: the nail-holes in the outer branch should be crowded towards
the toe and, under certain conditions, punched deeper than the wall is
thick, on account of the greater width of this branch; in the inner
branch the nail-holes are to be distributed back to the quarter and
punched light (see Fig. 118). Length will depend upon the obliquity of
the hoof. The outer branch should be about one-fourth of an inch longer
than the inner.
[Illustration: FIG. 117. A right front shoe for a base-wide (toe-wide)
hoof. The inner branch should be about one-fourth of an inch longer
than the outer.]
[Illustration: FIG. 118. A right front shoe for a base-narrow
(toe-narrow) hoof. The outer branch is wider and one-fourth of an inch
longer than the inner.]
6. _Shoe for a Wide Hoof._—Somewhat wider webbed (more covered) than
usual. Outer edge: bevelled under the foot all around (base-narrow).
Punching: nail-holes carried back into the posterior half of the shoe
(see Fig. 119). Length will depend upon the obliquity of the hoof.
7. _Shoe for a Narrow Hoof._—Outer edge: moderately bevelled under the
foot at the toe (base-narrow), elsewhere perpendicular. Distribution of
the nail-holes: regular. Direction of the nail-holes: perpendicular and
towards the quarters, inclining somewhat outward. The holes about the
toe incline somewhat inward. Length will depend upon the obliquity of
the hoof. Concaving unnecessary (see Fig. 120).
[Illustration: FIG. 119. Flat shoe for a round hoof (right front).]
[Illustration: FIG. 120. A left front shoe for a narrow hoof. The
concaving is unnecessary.]
The forms of shoes described in paragraphs 2 to 7 differ from that
described in paragraph 1, but are necessary in order to lessen the
injurious consequences of irregular loading (unbalancing) of the feet,
and of unfavorable bases of support of the body-weight.
G. Choosing the Shoe.
The choice of the shoe for a given horse is not at all difficult after
we have carefully considered his weight, the nature of his work, his
standing position, gait, the form of his hoofs, and quality of the
horn, bearing in mind the general and peculiar properties of shoes.
As a rule, we choose a shoe that is longer than the hoof, because the
latter grows and carries the shoe forward with it, and because the
quarters gradually become lowered by rubbing and wearing away upon
the branches of the shoe. The =length= of the shoe is of especial
importance. For horses employed for slow, heavy draft purposes the
shoe supplied with heel-and toe-calks should extend backward far
enough to support the bulbs of the heels. On the contrary, horses used
at a trot or gallop, as coach-and saddle-horses, require shorter shoes
(see Fig. 124).
The _weight_ of the shoe should be so adjusted to the demands of the
horse’s work, the condition of the legs (whether used up with work
or not), and the nature of the ground that the shoeing will last _at
least a month_. Hard roads and a heavy, clumsy gait require strong,
durable shoes, which, under some conditions, are to be rendered still
more durable by welding in steel. For moderate service upon soft roads
we should use light shoes. Running horses require unusually thin and
narrow shoes of steel (see Figs. 125-128).
H. Shaping and Fitting Shoes. General Considerations.
This is one of the most important parts of horseshoeing. Its object is
to so fashion or shape the shoe which has been chosen for a particular
hoof that its circumference will exactly correspond to the lower
circumference of the previously prepared hoof, and its bearing-surface
will fit air-tight to the bearing-surface of the hoof. At this time all
defects in the surfaces of hoof and shoe and in the nail-holes must be
remedied, the clips drawn up, and the shoe made to fit perfectly. The
bearing-surface of the shoe, especially at the ends of the branches,
must be kept =horizontal=[4] and smooth, and its width regulated by
the width of the bearing-surface of the hoof (see page 99). Perfectly
_uniform heating_ is absolutely indispensable in shaping the shoe,
because an irregularly heated shoe twists or becomes distorted at the
warm places. Every shoe should be straight, and when held before the
eye one branch should exactly cover the other. A flat shoe laid upon
a level surface should touch at all parts of its ground-surface; the
only exception to this is the shoe with a rolled toe (rolling motion),
in which the toe is turned upward. A shoe is termed “_trough-shaped_”
when only the inner edge of the web rests upon the flat surface. It is
faulty, disturbs the stability of the foot, and shifts the weight of
the body too much upon the quarters.
[4] The horizontal bearing-surface is in accordance with nature,
because the changes of form of the hoof which take place at the plantar
border of the wall, on burdening and unburdening the foot, should not
be interfered with. A horizontal bearing-surface best fulfils this
requirement.
[Illustration: FIG. 121.
Shod fore-hoof viewed in profile to show the “roll” at the toe.]
To front shoes we give a =rolled toe= (Fig. 121, rolling motion), by
which we mean a more or less pronounced upward turn of the toe of the
shoe. Ordinarily, the toe begins to turn up at the middle of the web,
and should be elevated about one-half the thickness of the iron. The
rolled toe corresponds to the natural wear of front hoofs, facilitates
the “breaking over” of the feet, and insures a uniform wear of the
shoe (see Fig. 86). The shoe is made moderately hot and placed on the
foot with the toe-clip against the wall exactly in front of the point
of the frog. The scorched horn should be repeatedly removed with the
rasp until a perfect-fitting bed has been made upon the bearing-surface
of the hoof. From the bearing-surface of the shoe to the inner border
of the web the iron must be free from the sole around its entire
circumference. The horn sole should not be burnt, because the velvety
tissue of the sole lies immediately above it. In the region of the
nail-holes the outer borders of shoe and wall should correspond. =The
nail-holes must under all conditions cover the white line.= From the
last nail-hale back to the ends of the branches, for hoofs of the
regular standing position of the limbs, the shoe should gradually widen
until it projects at each quarter from a sixteenth to an eighth of
an inch beyond the edge of the wall. The posterior half of the shoe
should, therefore, be somewhat wider than the hoof. The effect of
this will be to prolong the usefulness of the shoes. With respect to
the _width of the branches_, an exception arises in the case of _hind
shoes_, in which the inner branch, with few exceptions, should closely
follow the border of the wall; this will prevent interfering and
tearing off the shoe by the opposite foot.
[Illustration: FIG. 122. Left fore-hoof of normal position shod.]
Between the ends of the branches and the frog there should be enough
room, with few exceptions, to pass a foot-pick.
In order to judge of the width of a shoe which has been fitted to
the hoof, it is of advantage to seize the hoof in the left hand and,
extending it towards the ground, to observe from behind and above the
outer border of the shoe and the surfaces of the wall.
_Furthermore, the most important rule is that the shoe should always
have the form of the foot, so long as the form of the hoof remains
unaltered. In all hoofs that have already undergone change of form we
must strive to give the shoe that form which the hoof had before it
underwent change._ Such treatment will not only do the hoof no injury,
but, on the contrary, is of advantage to it, as it is well known that
in time the hoof will acquire the form of the shoe.
Shaping and Fitting Shoes. Special Considerations.
(_a_) _A shoe for a hoof of the regular form fits properly_ when the
outer border of the shoe in the region of the nail-holes closely
follows the outer edge of the wall, but from the last nail-hole to
the end of each branch extends beyond the wall from a sixteenth to an
eighth of an inch, the shoe is straight, lies firmly and air-tight
upon the bearing-surface of the hoof, the nail-holes fall exactly upon
the white line, and there is sufficient space between the frog and the
branches of the shoe for the passage of a foot-pick. The branches must
be of equal length.
While in fitting a shoe to a hoof of regular form we need pay attention
only to the form of the hoof, _it is very different when we come to
shape and fit shoes to hoofs of irregular forms_. _In these cases we
must consider not only the form of the hoof, but the position of the
limbs and the distribution of weight in the hoof_, because =where the
most weight falls the surface of support of the foot must be widened,
and where least weight falls= (=on the opposite side=) =the surface of
support must be narrowed=. In this manner the improper distribution of
weight within the hoof (an unbalanced foot) is regulated,—that is, is
evenly distributed over the surface of support. The manner in which
this is accomplished in the various forms of hoofs is as follows:
(_b_) _An acute-angled hoof_ requires the shoe described in paragraph
2, page 114. The branches must be long, because more of the weight
falls in the posterior half of the foot, and long branches extend the
surface of support backward, while the surface of support in front is
to be diminished by making the toe of the shoe base-narrow, either
by turning it up or by bevelling it in under the foot. A shoe for an
acute-angled hoof fits when it is otherwise related to the hoof as is
described in paragraph _a_, above.
(_c_) _An upright or stumpy hoof_ presents exactly reverse conditions
with respect to the distribution of weight within the hoof, and
is treated in an exactly opposite manner. The surface of support
should be increased at the toe and diminished at the quarters. This
is accomplished by a shoe possessing the peculiarities described in
paragraph 3, page 114, whose nail-holes are directed either straight or
slightly outward.
(_d_) _A base-wide hoof_ requires the surface of support to be widened
upon the inner side of the foot and narrowed upon the outer side,
because the inner half of the foot hears the more weight. A shoe having
the peculiarities described in paragraph 4, page 114, accomplishes this
end.
(_e_) _The base-narrow hoof_ is just the reverse of the preceding, and
requires a shoe whose peculiarities are described in paragraph 5, page
114. While in the normal standing position of the limbs, viewed from in
front, the ends of the branches of the shoe should be equally distant
from the middle of the median lacuna of the frog, this is not so in
the base-wide and base-narrow positions. In the base-wide position
the outer and in the base-narrow position the inner branch should be
somewhat farther from the median lacuna than the branch of the opposite
side.
[Illustration: FIG. 123.
The three principal forms of hoofs shod with flat shoes.]
(_f_) _The wide hoof_ has too large a surface of support, and,
therefore, the shoe designed for it should possess the peculiarities
enumerated in paragraph 6, page 115.
(_g_) _The narrow hoof_ has already too narrow a base of support,
and must not be made smaller; therefore, the shoe should not have a
base-narrow but a perpendicular outer border, as described in paragraph
7, page 115.
Shoeing Saddlers and Hunters.
_The shoes for saddlers_ (Park Hacks) should be light, short, and
fitted snug to prevent forging, interfering and pulling of the
shoes. The hoof-surface should cover the wall, white line and at
least one-fourth of an inch of the margin of the sole. An average
width of one inch is desirable. Both front and hind shoes should be
fullered and concaved on the ground-surface (convex iron). =The Front
Shoe=:—_Length_, should not project beyond the buttress more than
one-eighth of an inch. _Width_, an inch at the middle on the branches,
somewhat more at the toe, and less at the ends of the branches.
_Bevelling_, outer border, base-narrow all around. The ends of the
branches, and the heel-calks, in case they are used, are bevelled
strongly downward and forward under the foot. The toe is rolled from
the inner edge of the web, and provided with a strong central clip. Six
nails are sufficient (see Fig. 124).
[Illustration: FIG. 124.
A right front shoe with forging calks; suitable for a saddle-horse, or
hunter (convex iron).]
=The Hind Shoe=:—_Length_, the shoe may project from one-fourth to
three-eighths of an inch behind the buttresses. The toe should be well
rounded and somewhat blunt so that the horn of the toe will project
beyond the shoe an amount equal to one-half the thickness of the
wall. _Width_, somewhat less than the front shoe. The branches are of
equal thickness, and should carry heel-calks whose height equals the
thickness of the shoe. To guard against interfering the inside calk may
be omitted and the inner branch thickened, fitted snug and bevelled
strongly base-narrow. Clips are to be placed at inner and outer toes.
Seven nails are sufficient.
_The shoes for hunters_ do not differ materially from those suitable
for Park Hacks. The hunter’s shoes are somewhat lighter, and to guard
against injury to the feet by over-reaching and interfering, and
against the shoes being pulled by stiff mire and by treading, the shoes
must represent merely a prolongation of the hoofs, _i.e._, must be no
longer and no wider than the hoofs themselves. =The front shoe= of
narrow, convex iron is rolled at the toe and has a central toe-clip.
Forging heel-calks are advisable.
=The hind shoe= is set back at the toe, carries inner and outer toe
clips, an outer heel-calk and an inner interfering branch. Seven nails.
Shoeing Runners.
Racing plates are intended solely to prevent excessive wear and
breaking away of the wall, and to insure a secure foothold upon the
ground. The shoes are made as light as possible, but they must not be
so narrow and thin that they will bend or break. They are therefore
made of steel, wide enough to cover the bearing-surface of the wall,
white line, and an eighth of an inch of the sole. The ground-surface
is divided into two sharp edge’s by a deep, clean, fullering continued
entirely around the shoe. heel-calks are of no advantage. Front and
hind shoes carry six nails. The last nails are well back in the
quarters to prevent the spreading or bending of the light shoe. Front
shoes are provided with central toe-clips; hind shoes carry inner and
outer toe-clips and are set slightly under at the toe (see Figs. 125,
126, 127, 128). An _average weight_ running plate for a medium-sized
hoof is _three to four ounces_.
[Illustration: FIG. 125. A fore running plate, hoof-surface.]
[Illustration: FIG. 126. A fore running plate, ground-surface.]
[Illustration: FIG. 127. A hind running plate, hoof-surface.]
[Illustration: FIG. 128. A hind running plate, ground-surface.]
Shoeing Trotters and Pacers.
The shoes worn while the trotter or pacer is in training are somewhat
heavier than those worn while racing. Training shoes will average 40
ounces to the set, while trotting and pacing plates weigh from 16 to
28 ounces to the set. Of the six fastest trotters during the last year
(1912) the average weight of the front shoes was 6⅚ ounces, of the
hind shoes 4 ounces. Of the seven swiftest pacers of the same year the
front shoes averaged 5½ ounces, and the hind shoes 3⅝ ounces. In short,
_extreme speed at running, pacing or trotting demands as light a shoe
as can be made, which will at the same time furnish a bearing for wall,
white line and a narrow rim of the sole_.
In style of shoes there is no marked difference between trotters
and pacers—except in the hind shoes of pacers that cross-fire (see
“cross-firing,” p. 140). Open shoes predominate. Bar-shoes are used,
not to give frog pressure, but to stiffen and prevent spreading of
the shoe, when after a few days’ wear it becomes thin at the toe. The
average trotting and pacing plate is so thin that it would be weakened
by fullering, so most of them are stamped (punched). Six nails are
sufficient. Clips are seldom needed.
Pacers usually require a low circular grab or “rim” at the toe. This is
set flush with the outer border, is about one-eighth of an inch high
and is brazed on. Trotting plates are usually without toe-calks, though
many are fullered across the toe (corrugated) to furnish a grip upon
the ground.
On both trotting and pacing shoes the heel-calks should be low and
sharp and should run straight forward so as not to retard the forward
glide of the foot as it is set to earth heel first. The heel-calk
serves chiefly to prevent the lateral twist of the foot as the horse
takes the sharp turns of the track.
Freak shoes, toe-weights, side-weights, excessive length of hoof or
toe, and other unscientific appliances and methods of shoeing speed
horses are being gradually eliminated, and today the fastest are
dressed and shod in accordance with the principles enunciated in this
book.
Fitting Shoes to Heavy Draft-Horses.
What has been previously said concerning shoeing holds good here;
however, the conditions of shoeing are somewhat different in heavy
horses, and particularly with respect to hoofs which, without being
clearly diseased, have been injured by shoeing. The entire operation
requires more circumspection, because it is more difficult. In many
cases one will find that the width that has been advised for the
outer branch of the shoe at the quarter is not sufficient. Indeed,
if a horse has wry feet, and there is unequal distribution of weight
within the hoof, and we attempt in shoeing it to follow to the letter
the directions given on preceding pages, we would be apt to favor the
perpetuation of the defect. In such cases the slant of the wall at the
quarters is of the greatest practical value to us in estimating the
proper width for the shoe at this point.
[Illustration: FIG. 129. Left hind shoe with a broad, base-wide outer
branch for draft-horses that stand markedly base-narrow (close behind).]
When uniform setting down of the hoof and uniform wear of the shoe are
desired, every point in the coronary band in the posterior half of the
foot must receive support by the shoe. This applies particularly to the
outer halves of hoofs that are extremely base-narrow. If, for example,
the coronet of the outer quarter projects beyond the plantar border
of the quarter, the outer branch of the shoe from the last nail-hole
back must be kept so wide (full) that an imaginary perpendicular line
dropped from the coronary band will just touch the outer border of the
shoe. The inner branch, on the contrary, should follow the edge of the
wall as closely as possible. Furthermore, the new shoe should be given
more curve,—that is, made wider and fitted more full where the old shoe
shows greatest wear. _The principal thought should be to set the shoe,
which should always be regarded as the base of support of the hoof,
farther towards the more strongly worn side._ Such a practice renders
superfluous the wide-spread and popular custom of bending outward the
outer quarter and heel-calk of hind shoes. From the manner in which a
horse travels and the wear of the old shoe, we estimate the distance
that the branches of the shoe should be set from the middle line of
the hoof. If in following out this plan the bearing-surface of the
outer quarter of the wall is not completely covered, the quarter will
be pinched and squeezed inward; this should be prevented by a broader
branch punched so deeply that the holes will fall upon the white line
(Fig. 129).
When the shoer has satisfied himself that the shoe fulfils every
requirement and fits perfectly, it is to be cooled, the holes opened
with an oiled pritchel, and the shoe brightened with a file. In filing,
all sharp edges should be removed. If a shoe is to be filed upon the
outer border, to give it a neater appearance, the filing should be done
_lengthways of the shoe_, and _not crossways_; of course, the shoe must
not be bent by being improperly clamped in the vise.
It indicates much greater skill in making and fitting shoes when they
look clean and finished with little or no filing.
In the preceding remarks I have insisted upon a
horizontal bearing-surface for all shoes, with the
single exception of shoes provided with the rolled
toe (rolling motion). As far as I can judge from the
literature of shoeing, and from what I have seen
with my own eyes in many countries, this is the most
wide-spread practice. In Germany, on the other hand,
there is another method, followed in the military
shoeing shops, _which consists in placing the
bearing-surface of the shoe as nearly as possible
at right angles to the slant of the wall_.
According to this method the bearing-surface of
the shoe, depending upon the direction of the wall
(viewed from in front, from behind, and from the
side), should incline more or less, now backward,
now inward, now horizontal, and now outward. Shoes
for wide hoofs are given a bearing-surface which
inclines inward, while for narrow hoofs the shoes
have a horizontal bearing-surface. Shoes for wry
hoofs have a bearing-surface which inclines downward
and inward for the slanting wall, and for the steeper
wall a horizontal bearing-surface, which towards the
end of the branch may incline slightly downward and
outward. Besides, the bearing-surface of the ends of
the branches, viewed from the side, has a backward
and downward inclination. This method is practicable
=only in part=.
I. Nailing the Shoe.
This is that act of horseshoeing by which the shoe is fastened to the
hoof by special nails called hoof-nails or horseshoe-nails, which are
driven through the shoe and horny wall.
At present there are hand-made and machine-made horseshoe-nails. Both
kinds should be made of the best wrought iron. The nails must be
slender, wedge-shaped, and twice as wide as they are thick. Thickness
and length must be in proper relation to each other. We should never
choose a nail which is longer than is absolutely necessary to hold the
shoe; six to eight sizes are sufficient for all purposes.
The rough nails (hand-made), before being used, must undergo a special
shaping to prepare them to pass through the wall easily and in the
desired direction. This preparation is called _shaping and bevelling_.
In doing this we should see to it that the nails are made smooth, and
even, but are not hammered harder than is absolutely necessary, because
the lighter one can hammer the nails the better they will be.
[Illustration: FIG. 130. Hand-made horseshoe-nails, natural size, for
fullered shoes (1, not bevelled).]
Furthermore, we must give the nail that form which will insure its
passing through the horn _straight_ and _not in a curve_; with this
object in view, the nail is to be slightly curved so that the side
which is turned towards the frog in driving (inside) will be a little
concave, the opposite side convex (Figs. 130, 3, and 131, No. 10),
since it is known that a straight nail always passes through the horn
in a curve, and not only does not long remain tight, but is quite
likely to _press upon and injure the soft tissues_ of the foot. (See
also, Nailing.)
At the point of the nail the _bevel_ is to be so placed that it will
form a short one-sided wedge with the slanting side directed =from
within to without= (Figs. 130, 3, and 131, _d_). A short bevel is
suitable for nails that are to be driven low, while a long bevel makes
it possible to drive them high. _The bevel should never form a hook;
it must always be straight, should be sharp but not thin, and under no
conditions incomplete_ (defective).
[Illustration: FIG. 131. Machine-made horseshoe-nails (natural size)
with a low, wide head for a fullered shoe. The last nail is shown from
one border; the others from the inner face: _a_, head; _b_, neck; _c_,
shank; _d_, bevel; _e_, point; _f_, inner face; _g_, outer face.]
Machine-made nails, smooth, polished, bevelled, and ready for use, are,
for many reasons, to be preferred to hand-made nails, though the latter
are rather tougher (see Fig. 131).
Before the shoe is nailed on it should be cooled and again carefully
examined by a competent shoer, who should then place it upon the
hoof, where it should be critically observed to see whether it really
fulfils every requirement of a properly-fitting shoe. Afterwards, the
least fault or defect must be remedied, and then the work of _nailing_
it begins. By nailing, the shoe is firmly and durably fastened to the
hoof, in doing which the horn of the wall is spared so far as possible,
the elasticity of the hoof borne always in mind, and wounding of the
pododerm entirely avoided. =The nails must in all cases penetrate the
white line= and pass through the wall in such a straight direction
that they will appear neither too high nor too low upon its outer
surface. In the first case there is considerable danger of pricking or
close-nailing, and in the latter the nail-holes will tear out easily
when the nails are being clinched.
[Illustration: FIG. 132.
Driving hammer.]
In driving a nail, it should be held in the fingers as long as possible
in the direction in which it is desired that it shall pass through
the horn. A nail should be driven cautiously, with attention to its
_sinking and sound_, and yet with enough force so that at each stroke
it will penetrate from one-fifth to one-fourth of an inch. The power
required at each stroke will depend upon the hardness of the horn and
the size of the nail. Fearless driving and timorous tapping should not
be allowed.
Nails, which at a depth of five-eighths of an inch are still going
soft, or which bend and give a dull sound, or cause pain, should be
immediately withdrawn.
According to the size of the horse and his hoofs the nails should be
driven from five-eighths to an inch and five-eighths high, and as
_even_ as possible. As soon as a nail is driven its point should be
=immediately= bent down towards the shoe in order to prevent injuries.
The heads of all the nails should then be gone over with a hammer and
driven down solidly into the nail-holes, the hoof being meanwhile
supported in the left hand. Pincers are then held under the bent nails
and they are more sharply bent by _light_ blows upon the nail-heads.
The points of the nails are now nipped off near the hoof, the horn
which has been thrown out just below the clinches by bending the nails
down is removed with rasp or gouge, and the ends of the nails bent down
still more, but not quite flush with the wall. This operation is called
“clinching.” A clinching-block or a pair of ordinary blacksmith’s
pincers is then placed under the end of the nail, now called a clinch,
and by light blows (in doing this the nail must not bend within the
wall) upon the head the clinch is turned closer to the surface of the
wall; finally, with the front edge of the nail-hammer the clinch is
hammered down flush with the wall. On the inner half of the wall the
clinches should not be felt on stroking the wall with the fingers. The
small amount of horn that projects beyond the shoe around the toe may
be carefully rasped away in the direction in which the wall slants, but
_never higher than the clinches_; finally, the sharp lower edge of the
wall is to be removed by carrying the corner of the rasp around between
the shoe and the horn.
A clinch is sufficiently long when it equals the width of the nail at
that point.
It is of advantage to use a shoeing-bock or foot-stool in clinching
the nails on the front hoofs. The hind hoofs may be clinched in the
hands. Then the horse should be led out and again moved in order to
see whether or not the new shoeing has actually accomplished what was
desired. Finally, the entire hoof should be given a thin layer of
hoof-salve.
K. Horseshoes More or Less Deficient in the Desirable Qualities
Described on Pages 107-116.
Machine Shoes.
1. _Machine Shoes of Wrought Iron._—They are half-finished and
finished. Though machine shoes with few exceptions show no distinction
between front and hind, or left and right, with correct punching for
these different feet, but usually present one form in different sizes,
yet, unfortunately, they are in high favor with horseshoers, because
they may be used for both summer and winter and for bar-shoes.
[Illustration: FIG. 133.
A machine-made (drop-forged) front shoe, ground-surface.]
[Illustration: FIG. 134. A machine-made toe-weight front shoe for a
harness horse, showing ground-surface. Punching good.]
For these reasons we cannot approve of machine shoes.
2. _Finished Cast Shoes._—They are of four kinds,—ordinary cast shoes,
cast shoes with rope buffer, cast shoes with fiber buffer, and cast
shoes fenestrated to hold a rubber buffer. Ordinary cast shoes of
correct form and proper punching designed by Grossbauer, of Vienna, are
sold by Hannes’ Sons, of that city.
[Illustration: FIG. 135.]
[Illustration: FIG. 136.]
[Illustration: FIG. 137.
Machine-made (drop-forged) multi-calk fore shoe. _A_, ground-surface;
_B_, hoof-surface; _C_, profile.]
[Illustration: FIG. 138.]
[Illustration: FIG. 139.]
[Illustration: FIG. 140.
Machine-made (drop-forged) multi-calk hind shoe. _A_, ground-surface;
_B_, hoof-surface; _C_, profile.]
_Rope Shoes._—These shoes have a groove on the ground-surface, in
which rests a tarred rope, which greatly diminishes slipping on smooth
pavement. For this reason alone they are extensively used in the large
cities of Germany. Since the open rope shoe, when half worn out, will
warp, the bar rope shoe is more satisfactory and more extensively used
(Figs. 141-144).
[Illustration: FIG. 141. Bar rope shoe with bar bent forward.]
[Illustration: FIG. 142. The same with bar bent backward.]
[Illustration: FIG. 143. The same with beak-formed bar.]
[Illustration: FIG. 144. An open rope shoe.]
Before fitting the shoe the rope must be removed. After the nails are
driven it is laid in the groove and hammered into place. Rope shoes can
seldom be fitted properly to hoofs other than those which are healthy
and of regular shape.
_Fiber Shoes._—These have a groove on the ground-surface into which
layers of linen fiber belting have been tightly pressed. The fiber
cannot be removed, and therefore the shoes cannot be heated, but
must be fitted cold. The nail-holes are placed between the fiber and
the outer border of the shoe, and are punched too light. The bearing
surface of the shoe is unsupported, so that when the shoe is half worn
out, it warps. There is no distinction between rights and lefts.
_Rubber shoes_ have all the defects of fiber shoes, and one more.
The hoof-surface is covered with canvas, which under normal and
acute-angled hoofs wears through under the quarters and leads to
loosening of the last nails.
L. Rubber Pads.
The increasing use of asphalt, tarvia and other hard, smooth and
slippery materials for surfacing city streets and country highways has
not only made travelling in flat and even in calked shoes precarious,
but has aggravated all those injuries produced by concussion.
To prevent slipping and the injurious effects of concussion a great
many shoes have been devised, in which are incorporated such materials
as hemp rope, linen fibre, papier maché, cork, wood, bast, felt and
rubber, but all fail in greater or lesser degree to meet practical
requirements.
Rubber, though the most expensive of these materials, is the most
resilient and takes the best grip on smooth pavement. A pad of rubber,
wide enough to cover the branches of the frog alone, or the branches of
the frog and the buttresses of the hoof, firmly cemented to a leather
sole, constitutes the modern rubber pad (Figs. 145, 146, 147).
[Illustration: FIG. 145. A light driving pad, gummed and stitched to a
leather sole; seen from the ground-surface and in profile. Used with a
seven-to ten-ounce short shoe. _a_, stitching; _b_, rubber bar under
buttress and frog; _c_, leather sole.]
The frog- and buttress-pad used with a short shoe is to be preferred to
the earlier frog pad which takes a full shoe.
_The advantages of rubber pads are_:
1. They prevent slipping upon asphalt and other smooth, dry surfaces.
2. They diminish concussion, and are valuable in the prevention and
treatment of sore heels, dry and moist corns, bruised sole, and
incipient side-bone.
[Illustration: FIG. 146. Air-cushion pad, seen from ground surface and
in profile. Suitable for light harness horses.]
[Illustration: FIG. 147. A heavy bar-pad suitable for heavy harness and
draft-horses on pavement. The short shoe may carry a toe-calk of medium
height.]
3. They give frog pressure, develop the frog and tend to prevent
contraction of the quarters and those lesions which may follow
contraction, as corns, cracks of bars and quarters, laminitis of the
quarters and thrush.
_A rubber pad should not be used_:
1. In contraction of one or both quarters, when the frog is too much
shrunken to bear upon the pad.
2. In lameness from well developed side-bones.
3. In navicular bursitis (“navicular disease”).
4. In thrush, or canker of frog or sole.
Rubber pads, light, medium and heavy, are made in all sizes and are
suitable for all classes of horses, from the light roadster to the
heavy draft type. The short shoe with which they are used reaches
the middle of the quarters. The pad surface (upper surface) of the
ends of the branches should be bevelled to conform to the pad, and to
hold it firmly against the frog and buttresses. The thickness of the
shoe should equal two-thirds the thickness of the pad, so that when
fitted one-third of the thickness of the pad shall project below the
ground-surface of the shoe. The shoe should be provided with a strong
toe-clip. With the heavy, thick pad of a draft-horse a low toe-calk may
be used, but heel-calks should never be put on a short shoe. Pads are
seldom necessary on the hind feet.
CHAPTER IV.
SHOEING HORSES THAT FORGE AND INTERFERE.
A. Forging.
Forging is that defect of the horse’s gait by reason of which, at a
trot, he strikes the ends of the branches or the under surface of the
front shoe with the toe of the hind shoe or hoof of the same side.
Forging in a pacer is termed “cross-firing” and consists in striking
the inner quarter, or the under surface of the inner branch of a front
shoe with the toe of the diagonal hind shoe or hoof.
Forging is unpleasant to hear and dangerous to the horse. It is liable
to wound the heels of the forefeet, damages the toes or the coronet of
the hind hoofs, and often pulls off the front shoes.
[Illustration: FIG. 148. Right front shoe with concave ground-surface
(“convex iron”) to prevent “forging.”]
[Illustration: FIG. 149. Right hind shoe with lateral toe-clips to
prevent “clicking” and the various injuries due to forging.]
_Causes._—1. Faulty conformation; for example, horses that stand
considerably higher at the croup than at the withers; horses with
long legs and short bodies; horses that “stand under” in front and
behind. 2. Using horses on heavy ground, unskilful driving, allowing
a long-necked, heavy-headed horse to carry his head too low; riding
without holding a horse to his work by feeling his mouth and pressing
the knees against his sides. 3. Fatigue frequently leads to forging,
even in horses that are well built and properly shod. It may also occur
in the act of vaulting over an obstacle. 4. Poor shoeing, especially
too long toes upon the front and hind hoofs, and too long front shoes.
The aim of the shoer should be to facilitate the quick and easy
“breaking over” of the =front foot=, so that it may get away before
it is overtaken by the hind foot. The toe of the front hoof should be
fairly short and rolled; the quarters spared. The front shoe should be
light, rolled at the toe and =no longer and no wider= than the hoof.
The ends of the branches of a flat shoe, and also the heel-calks, in
case they are needed to elevate a heel that is too low, should be
bevelled from the hoof-surface of the shoe downward and forward under
the foot. Such short heel-calks, bevelled to prevent forging, are
called “forging calks.” If the horse continues to forge between the
branches and against the ground-surface of the shoe, concaving this
surface will prove advantageous (convex iron). The form of the front
shoes of horses that forge should represent merely a prolongation of
the hoof.
The “breaking over” of the =hind foot= should be delayed by sparing
the toe and lowering the quarters, but not sufficiently to break the
foot-axis too far backward. The hind shoe is to be squared at the toe
and the lower edge of the shoe in the region of the toe well rounded;
instead of a toe-clip, two side-clips are to be drawn up and the shoe
so fitted that at least three-fourths of the thickness of the wall of
the toe, with the edge well rounded, will extend forward beyond the
shoe. Should the toe of the hoof be short it may be raised either by a
low toe-calk set one-fourth of an inch back from the edge of the shoe,
or by thinning the shoe from the toe to the ends of the branches. The
branches of a flat hind shoe should extend somewhat farther back of
the buttresses than under normal conditions, to trail upon the ground
just before the hoof alights, and acting as a brake, to bring the hoof
to earth (Fig. 150).
[Illustration: FIG. 150. Hind shoe with swelled toe to slow the
breaking over. Often efficient when the hoof is too short at the toe:
_a_, long branches to trail and bring the foot to earth; _b_, outer toe
clip; _c_, toe squared and set under to prevent injury to front hoof,
and to deaden the sound of forging.]
“Cross-firing” is most apt to occur and is most dangerous at extreme
speed. Then, when the inner branch of the hind shoe strikes the inner
heel, quarter or shoe of the diagonal front foot, both feet are in the
air,—the fore foot is approaching the middle of its stride, while the
offending hind foot is in the last third of its flight. The standing
position that favors cross-firing is the base-wide (toe-wide) in front,
and the base-narrow (toe-narrow) behind. With this direction of limbs
the flight of the fore feet is forward and inward during the first
half of their stride, while the flight of the hind feet is forward and
inward during the second half of their stride (see Figs. 72, 73, 75).
The problem is, therefore, so to pare and shoe a base-wide fore foot
that it will break over nearer the centre of the toe and thus execute
less of an inward swing during the first half of its stride, and to so
pare and shoe a base-narrow hind foot that it will break over nearer
the centre of the toe and thus execute less of an inward swing during
the second half of its stride. Neither a toe-wide nor a toe-narrow
foot can be made to break over the exact centre of the toe, and yet it
is possible by dressing the hoof and by shoeing to shift the breaking
over point nearer to the centre of the toe, and by doing so, to alter
slightly the lines of flight of the feet.
Dressing and shoeing the front foot: =The hoof= should be relatively
low from the middle of the toe around to and including the _outer_
buttress. If the inner half of the wall is deficient in length it must
be raised above the outer half by applying a shoe which is thinner in
its outer than in its inner branch. The inner toe should be left long.
[Illustration: FIG. 151.
Left hind hoof of a toe-narrow pacer, shod to prevent cross-firing:
_a_, dotted line indicating outer border of the hoof; _b_, long bent
outer branch; _c_, short, thin inner branch; _d_, inner wall extending
beyond the shoe; _f_, line from which inner branch is feather-edged.
The shoe is of even thickness from _b_ to _f_ at inner toe; but from
latter point to _c_ diminishes to a feather edge.]
[Illustration: FIG. 152.
Front view of hoof and shoe depicted in Fig. 151: _a_, outer branch
fitted very full and bevelled base-wide; _b_, inner branch diminishing
in thickness from inner toe _c_, to its termination at the inner
quarter. Designed to favor “breaking over” near centre of the toe, and
to widen the gait.]
=The shoe= should be light, without heel-calks, but may carry a low,
curved grab (“grab,” is a low, straight or curved, toe-or heel-calk on
a racing plate) running from the second inner toe nail to the centre
of the toe. _The inner branch_ is to be fitted flush with the wall
from the centre of the toe back to the quarter, back of which point
it gradually extends beyond the wall, _i.e._, is fitted full; and
terminates well back of the buttress. _This inner branch_ should be
from one-fourth to three-eighths of an inch longer than the outer
branch. _The long inner branch, full at the quarter, is desirable, but
must be covered by a quarter-boot, which a cross-firer should always
wear._
_The outer branch_ should be fitted snug and terminate at the buttress.
From the centre of the toe to the end of the branch the ground-surface
should be bevelled from the inner edge of the web to a knife-edge at
the outer border.
Dressing and shoeing the hind foot: =The hoof= should be relatively
low from the centre of the toe around to and including the _inner_
buttress. If the outer half of the hoof is deficient in length, it must
be raised above the inner half by applying a shoe with a thin inner
branch. The inner branch may terminate in a knife-edge midway between
toe and heel (Figs. 151 and 152).
_The inner branch_ is to be fitted snug from the centre of the toe to
its end, and its ground-surface should be bevelled from the inner edge
of the web to a knife-edge at the outer border.
_The outer branch_ is to be fitted very full from the outside toe to
the end. This branch should extend well behind the buttress, and in
well-marked base-narrow hoofs should be turned outward in order to
support the overhanging coronet of the quarter. The outer border should
be bevelled base-wide, and the nail-holes punched coarse, _i.e._, far
in from the outer border (Figs. 151 and 152). The outer branch may
carry a small heel-calk.
B. Interfering.
A horse “interferes” when a hoof in motion strikes the opposite
supporting leg. Interfering is apt to produce injuries, either of the
coronary band of the inner half of the foot or of the fetlock-joint, or
(in fore-limbs) of the cannon, even as high up as the knee. Lameness
frequently accompanies such injuries.
_The causes of interfering_ lie either in the _shoeing_ (of the foot
that strikes, as well as of the foot which is struck), in the _position
of the limbs_, or in the _use_ of the animal. Horses that have the
correct standing position do not interfere when they are properly shod;
base-wide horses interfere sometimes; horses base-narrow down to the
fetlock and toe-wide below that point interfere very frequently. Traces
of unequal length, weariness, and shoeing at too long intervals favor
interfering.
In attempting to lessen or remove interfering, the horse must be most
carefully examined with respect to the position of his limbs, his gait,
and his shoeing, in the manner described on pages 90 to 92.
[Illustration: FIG. 153.
A right front shoe with nailless and narrow inner branch for a
base-wide hoof. Suitable for horses that strike anywhere from inner toe
back to the quarter.]
If the cause is found to be the twisted position of a shoe, too wide
hoofs, raised clinches, etc., nothing need be done further than to
correct the shoeing; but if a faulty position of the limbs is the
cause, we must ascertain the exact part of the hoof that does the
striking, diminish the size of the hoof at that point, regulate the
entire plantar surface of the hoof, make the shoe straight along
the region that strikes,—that is, without curve,—and so fit it to
the foot that one-third of the thickness of the wall will extend
beyond the shoe. Where interfering is so pronounced as to produce
serious injuries, we use a shoe with no nails in the inner branch
(“dropped-crease” shoe) (Figs. 153, 156, 157).
[Illustration: FIG. 154.
Left hind shoe with interfering branch (ground-surface), for
base-narrow standing position.]
[Illustration: FIG. 155. The same (hoof-surface).]
[Illustration: FIG. 156.
Left hind interfering shoe without nail-holes in inner branch
(“dropped-crease” shoe): _a_, side-clip.]
[Illustration: FIG. 157.
Right hind shoe for toe-cutters. The dotted lines indicate the distance
that the wall projects beyond the shoe: _a_, side-clip.]
The so-called _interfering shoes_ (Figs. 154 and 155) are worthy
of recommendation only for hoofs of the base-narrow position. The
interfering branch, whose greater thickness raises the inner wall,
which is often too low, is to be so shaped and directed that the hoof
will project somewhat beyond it. _This interfering branch must be
made and shaped in accordance with each individual case._ The holes
in the interfering branch should be punched somewhat finer (nearer
the edge) than usual. Interfering shoes in which the nail-holes, with
the exception of the inner toe nail-hole, are placed in the outer
branch, are called “_dropped-crease interfering shoes_” (Fig. 156).
Such shoes are not recommended for hind hoofs that are decidedly
toe-wide (toe-cutters); in such cases better results will be obtained
by using a shoe, either with or without heel-calks, whose inner branch
is straight and without nails along the striking region, and is fitted
wide (full) at the quarter. The inner branch should be from one-fourth
to three-eighths of an inch longer than the outer. The inner heel-calk
should be higher than the outer, and the end of the outer branch should
be as base-narrow as it can be made (fitted close) (Fig. 157). In order
to prevent shifting of an interfering shoe, a side-clip should be drawn
up on the outer branch (_a_).
There is no manner of shoeing that will prevent interfering which is
caused by improper harnessing, crooked hitching, or weariness. The
simpler and the _lighter_ the shoes the less will horses interfere.
CHAPTER V.
WINTER SHOEING.
All shoes whose ground-surface is provided with contrivances to prevent
slipping upon snow and ice are called winter shoes.
[Illustration: FIG. 158. An ice-nail, frost-nail.]
These various contrivances are produced by several processes called
“methods of sharpening.” All methods may be gathered into two
groups,—namely, _practical_ sharp-shoeing and _impractical_. Only the
first will be considered.
The durability of sharpened shoes depends partly upon whether they
are made of steel or iron, and partly upon the nature of the ground
in winter. If the ground is continuously covered with a thick layer
of snow, whatever method of sharpening is followed, the shoes =stay
sharp=; if, however, the winter is open, changeable, with more bare ice
than snow, no method of sharpening, whatever it may be, will last long;
the shoes will =not stay sharp=.
For these reasons no method of sharpening which fulfils all conditions
satisfactorily has yet been discovered.
The simplest and at the same time the least durable method of
sharpening is: 1. That by means of =ice-nails= or =frost-nails= (Fig.
158). One or two nails are drawn from each branch of the shoe and
replaced with ice-nails.
2. =Sharp Toe- and Heel-Calks.=—The outer calk is split and a small
steel wedge welded in. It is then laid upon the edge of the anvil,
indented and sharpened from within to without in such a manner that
the calk shall be thin from the branch to the ground, and the outer
surface shall be in the same vertical plane as the outer edge. If a
calk is narrow from its base to its end, and at the same time without
flaw, it does not need a sharp cutting edge. The inner calk should
never be sharpened except the ground be very slippery. The cutting edge
of this inner calk stands at right angles to the length of the branch,
and its outer corner should then be rounded to prevent its injuring the
opposite foot (Figs. 159, 160).
[Illustration: FIG. 159.]
[Illustration: FIG. 160.
Outer and inner heel-calks sharpened.]
For horses used for heavy draft purposes a toe-calk is welded to the
shoe and sharpened. For this purpose we use only steel (toe-steel),
which is easily welded to the shoe and remains firm. Toe-calks and
steeled heel-calks are tempered, in order, as much as possible, to
lengthen their period of durability. This method of sharpening is the
oldest and most wide-spread, and is employed on the shoes of all horses
of which we require more than light service.
[Illustration: FIG. 161.
Left fore-hoof sharp-shod: _a_, toe-calk bevelled from in front;
_b_, outer heel-calk directed lengthwise with the branch; _c_, inner
heel-calk, half sharp and directed transversely to direction of the
branch.]
Hoofs are easily damaged or even ruined by frequently repeated
sharpening of the shoes, because every time this is done the shoes must
be removed and replaced.
3. =Shoeing with Screw Heel-Calks.=—Any ordinary flat shoe not too thin
and narrow at the ends of the branches can be changed to a shoe with
screw heel-calks by punching holes in the ends of the branches and
cutting a thread in them.
[Illustration: FIG. 162.
Ground-surface of the end of a branch of shoe, showing (_a_) hole and
counter-sinking for a screw-calk (one-half natural size).]
The screw heel-calk holes are made either by punching or boring. The
punching is done by means of an almost cylindrical hammer-punch,
afterwards finishing the holes by driving through them a round punch
which tapers from the middle towards both ends. On the ground-surface
of the shoe the hole is moderately counter-sunk (Fig. 162, _a_), so
that after the thread has been cut and the calk screwed into place the
shoulder of the latter will rest on the counter-sinking.
At present nearly all screw-calks are made by machinery, either of iron
or toe-steel. The former is too soft and therefore not sufficiently
durable; the latter, however, is quite durable when the calk is
properly hardened (tempered) by heating to a cherry-red, sticking
the head of the calk as far as the tap into a bed of moist sand, and
allowing it to slowly cool.
The chief requirements of a good screw-calk are, further, a =clean,
deep=, but not too coarse =thread=, and but _one size of thread and tap
for all calks_, so that every calk will fit in every shoe. A calk whose
tap measures one half-inch (12.7 millimetres) (Whitworth) in diameter
is sufficient for the heaviest shoes. The tap which is used to cut
the thread in the holes for the screw-calks must be about ¹/₁₂₅ of an
inch thicker than the head of the calk. In the German army the calks
have a tap fifteen thirty-seconds of an inch in diameter. The coachman
should be given four calks (sharp and blunt) for each shoe, and a
small screw-calk key for placing and removing them. Screw toe-calks
are also used, yet they require special security to prevent their
becoming loose. Experimentation with the screw toe-calks, though not
yet entirely satisfactory, cannot be said to have ended.
The advantages of shoes provided with good screw heel-calks are so
manifold that they deserve marked preference over shoes sharpened
by the ordinary methods. The common objections urged against
screw-calks,—namely, that they loosen and are lost, or break off, are
not worthy of serious consideration, since these evils are merely the
result of unskilful workmanship and poor material. _Shoes with screw
heel-calks are the best shoes for winter, especially for horses that
have to work hard and continuously._
[Illustration: FIG. 163. Sharp screw-calks with Whitworth thread
(half-inch, natural size).]
[Illustration: FIG. 164. Whitworth tap (half-inch, half natural size).]
Balling with snow is prevented by using shoes narrow in the web and
concave upon the ground-surface (convex iron), and thoroughly oiling
the sole and frog. Sole-pads of felt, leather, or straw serve the
same purpose. Balling with snow is _best_ prevented by a rubber
sole-and-frog pad, or by a “stopping” of a patent hoof cement known in
Germany as “huflederkitt.”
4. =Shoeing with Peg-Calks.=—The calks are merely stuck into the
calk-holes, hence their name. Round and square peg-calks are used, but
the former are better than the latter.
The inventor of round peg-calks is Judson, an American. The shoes
differ in no respect from the ordinary flat shoes. It is necessary that
the tap of the calk have a moderately conical form, and exactly fit
into the calk-hole of the shoe. The taper of the calk-tap is correct
if for every ten thirty-seconds of an inch in length it increases or
diminishes one-thirty-second of an inch in diameter (equal to one inch
in every ten inches of length).
[Illustration: FIG. 165. Sharp peg-calk (cog): _a_, the tap; _b_, the
head.]
[Illustration: FIG. 166. Blunt peg-calk: _a_, the tap; _b_, the head.]
[Illustration: FIG. 167. Lower part of the reamer.]
Although the calk-holes may be punched in a hot shoe, yet boring and
reaming them is much better, because by this method a more perfect fit
can be secured. For this purpose we require a drill (a spiral drill is
the best) whose diameter is exactly the same as that of the small end
of the calk-tap (Figs. 165, _c_, and 166, _c_). After the shoe has been
fitted to the hoof, the provisional holes are drilled and afterwards
reamed out from the ground-surface of the shoe with the reamer shown in
Fig. 167. Since the tap of the reamer corresponds exactly in size to
the tap of the calk, it is evident that the latter must exactly fit and
be tight. The wire edge that is raised around the hole is removed with
a file, and the edge then smoothed by introducing the reamer a second
time. The calks are made of rolled round steel, which has the thickness
of the tap-end of the calk. For this purpose we require a calk-mould or
matrix, in which one or more holes have been finished with a reamer.
A piece of rod steel is heated at the end for a distance nearly twice
the length of the calk, is swaged, thrust into the matrix, then broken
off, and back-set. This will give a blunt peg-calk. If a sharp calk is
desired, the upper part of the head of the calk is sharpened in the
ordinary manner, although this is accomplished most easily by using a
pair of tongs with short jaws that are hollowed upon the inside for
seizing the tap of the calk.
Before the shoes are nailed on, the normal punch should be oiled and
driven into the calk-holes, and the calks passed into the holes to see
that they fit perfectly.
The calks are driven into place =after= the shoes are nailed to the
hoofs. A light blow is sufficient to fasten a calk, yet a necessary
precaution is first to remove every trace of oil from the calks and
calk-holes. The first calk driven into place must be held with the hand
while the second is being driven, otherwise it will either spring from
the calk-hole or be loosened so that it will soon afterwards be lost.
To remove such a calk we strike its head from different sides with a
hammer, stone, or other hard object until it becomes loose, when a
rather hard blow upon the shoe causes it to spring out. Calks which
have worn down are seized by a pair of sharp nippers and loosened by
blows upon the shoe. Since a calk which is firm soon rusts and is then
very difficult to remove, it is recommended that all calks be removed
every night.
The =advantages= of peg-calks over screw-calks are: 1. They do not
break off. 2. They are easier to make and simpler to use. 3. They are
=cheaper=.
=Disadvantages.=—1. Peg-calks are sometimes lost, even when properly
made and most carefully introduced. This evil happens much less
frequently when the calks are put in by the maker (horseshoer) than
when they are stuck in by the coachman, attendant, rider, or other
person. When calks are lost on the way from the shop, it is usually due
to some fault in the calk-holes or in the calks, although when the feet
are balled with snow the calks are easily lost, because they do not
then touch the ground.
2. The removal of the calks often involves many difficulties, since
they are apt to rust into place if not removed daily, and when worn
down so far that they cannot be grasped with the pincers are almost
impossible to remove. By hammering upon the calks and shoe many horses
are rendered not only restive, but sensitive in the feet.
3. If horses are used without the calks, a wire edge forms around the
hole on the bottom of the shoe, which interferes with the placing of
the calk and lessens its security.
The =hollow peg-calk= (Fig. 168), made by Branscheid & Philippi, of
Remscheid, has considerable merit. It holds exceedingly well, and is
very durable. It is furnished in three sizes,—Nos. 12, 13, and 14,—of
twenty-seven, thirty-one, and thirty-four millimetres length, and
twelve, thirteen, and fourteen millimetres diameter at the end of the
tap.
A punch is furnished which, when driven up to its head in the holes of
the heated shoe, insures a proper width and shape of the hole and an
accurately fitting calk.
[Illustration: FIG. 168. Hollow-spring peg-calk, No. 12.]
[Illustration: FIG. 169. Peg-puller.]
The calks may be removed by an extractor (Fig. 169) having at one end
a thread which is screwed into a corresponding thread on the inside
of the hollow calk, when by a few hammer blows on the shoe the calk
loosens. To prevent the calk becoming choked with dirt, a piece of cork
is thrust into the hollow. It may be easily removed by means of the
corkscrew at the other end of the extractor.
5. =Shoeing with Peg Toe-Calks.=—These are an invention of considerable
worth, especially for heavy draft in hilly country. They render better
service on hind than on front shoes.
Peg toe-calks with a single tap are simpler and preferable to those
with two taps. Every known contrivance to prevent the occasional loss
of the peg toe-calk is impractical.
The shoe for a peg toe-calk should be of good tough material and
without a flaw. The toe of the shoe should be about one-twelfth to
one-tenth of an inch thicker than the branches.
The hole for the peg toe-calk, whatsoever its shape may be, must be
smooth and uniform, with clean, true corners. Semi-circular holes
should present the convex side towards the toe.
Before punching, draw up the toe-clip. A punch-plate with a good-sized
hole, and a tap which will fit into the square hole in the anvil will
facilitate the work. The punch-plate when in position should be flush
with the front edge of the anvil. Place the toe of the shoe, hoof
surface upward, over the hole of the punch-plate, and drive a hole with
a punch-hammer which is perceptibly thinner than the model punch. Now
turn the shoe over, punch back from the ground-surface, and then file
away the wire edge which the punch has raised on the ground-surface.
Next, take a hand-punch, the end of which should just enter the hole,
punch through from the ground-surface, and correct any bulging by
dressing lightly over the horn of the anvil. Finally, use the model
punch to give the hole the exact size and smoothness.
Should the hole in the toe of the shoe enlarge in time, as sometimes
occurs, then back-set when necessary on removing the shoe. Backsetting
is easiest with the half-round hole, because the curved side, being
turned forward, runs approximately parallel to the outer border of the
toe of the shoe.
[Illustration: FIG. 170. Cross-section of different forms of peg
toe-calk taps.]
A good serviceable peg toe-calk must possess the following
characteristics:
1. The tap must be of such shape as not to turn;
therefore, not round.
2. The tap must be cone-shaped, and diminish in
diameter about one-thirty-second of an inch for each
one-fourth of an inch of its length from base to
apex. If the tap has less taper it will enlarge the
hole in the shoe till the head of the calk comes into
contact with the shoe, when the calk will loosen and
drop out.
3. The tap must be full-formed and smooth.
4. It must fit air-tight in the toe, and a single
hammer-blow should be sufficient to fix it securely.
5. The =head= of the toe-calk =must not rest
on the shoe=; a space of one-sixteenth of an inch
should intervene.
While a shoer of average mechanical ability can make a faultless peg
toe-calk, it is not profitable to do so while good machine-made calks
are to be had very cheap.
[Illustration: FIG. 171. Chisel toe-calk. (Doring.) No. 1 from the firm
of Branscheid & Philippi, of Remscheid.]
[Illustration: FIG. 172. Shovel toe-calk.]
[Illustration: FIG. 173. Peg toe-calk shoeing after Fisher-Renker, of
Dresden.]
[Illustration: FIG. 174. Peg-calk (shovel-calk) after
Kunze-Klotzsche-Königswald, of Dresden.]
The best forms in use are the quadrangular heads, with oval, half-round
(Figs. 171 and 172), and with two taps (Figs. 173 and 174).
In several European countries the peg toe-calks with half-round tap and
with two round taps are in use. To make good peg toe-calk shoes and fit
the calks properly requires =more than ordinary knowledge and skill=.
Poor work does much harm. Therefore, work carefully and get well paid
for it.
6. =Removable Heel-Calks that do not Require Sharpening.=—The
undeniable fact that all chisel-shaped or pyramid-shaped sharp calks
become dull in time, and must then either be sharpened or replaced
by new calks, renders shoeing not only costly, but injurious to the
hoofs and annoying to the owner. This drawback is most pronounced in
large cities, where the snow never lies long upon the streets, and the
horse just sharp-shod is soon obliged to travel upon bare pavements.
Attempts have been made to lessen this annoyance by the use of calks
that do _not require sharpening_, and yet which will prevent slipping
even after they have been used for a long time upon bare pavements.
It cannot be denied that such calks have considerable value, and,
except when the ground is covered with ice, many of these calks render
excellent service. Just as the ordinary sharp calks are satisfactory
and very durable outside of the large cities, so now for the first
time a few of these recently invented sharp calks seem to be worthy of
recommendation for city use. The following are the best:
[Illustration: FIG. 175. Screw-calk with H-formed cross-section.]
[Illustration: FIG. 176. Screw-calk with +-formed cross-section.]
1. Screw-calks and peg-calks with H-shaped
cross-section (Fig. 175).
2. Screw-calks with +-shaped cross-section (Fig. 176).
3. Screw- and peg-calks with O-shaped cross-section (Fig. 176).
4. Screw- and peg-calks with S-shaped cross-section.
5. Angle-calks (Fig. 177).
6. Screw- and peg-calks with rubber foot-pad.
7. Screw-calks with Y star-shaped cross-section (Fig. 178).
8. Hollow wedge-calks (Fig. 179).
9. Perforated screw-calks (Fig. 180).
[Illustration: FIG. 177. Corner calk.]
[Illustration: FIG. 178. Star calk.]
[Illustration: FIG. 179. Hollow calk.]
[Illustration: FIG. 180. Perforated calk.]
There is no doubt that the grip that these calks take upon the ground
and their durability depend upon the diameter and the arrangement of
their surfaces of friction. From all experiments made thus far it is
shown that those calks which have narrow and comparatively few surfaces
of friction are the least durable.
[Illustration: FIG. 181. Universal screw-calk key with tap.]
[Illustration: FIG. 182. Felber’s hand-vise to secure the hoof from
twisting while changing the screw-calks.]
To introduce and remove the calks we use a calk key or wrench. For the
shop, the ordinary fork key (Fig. 181), the jaws of which are tempered,
is recommended. It fits all calks.
CHAPTER VI.
HOOF NURTURE.
Hoof nurture comprises all those measures which are employed to keep
hoofs healthy, elastic, and serviceable.
A. Care of Unshod Hoofs.
The care of the hoofs of colts is of special importance. _Abundant
exercise_ upon dry ground which is not too stony is most beneficial.
Such exercise will cause the hoofs to wear gradually, and it will only
be necessary from time to time to observe whether the wear is taking
place uniformly, and if not, to correct the uneven wear with the rasp.
[Illustration: FIG. 183.
Twisted left front long pastern of colt, viewed from the upper
articular surface. The lower end has been twisted toward the left: _a_,
transverse axis of lower articular surface; _b_, transverse axis of the
upper articular surface.]
If colts are reared in the stable, the horn continuing to grow down
does not undergo sufficient wear, and changes in form of the hoof,
and even permanent distortions of the bones of the foot gradually
occur. The wall becomes too long and bends or sometimes separates from
the sole and keraphyllous layer. Weak quarters bend (curl) inward
and encroach upon the space occupied by the frog (contracted feet of
colts). The toe becomes too long, and this gives rise to too steep a
position of the pastern and causes an insecure and diffident gait;
therefore the hoofs must be shortened from time to time. The in-curved
quarters should be removed with the hoof-knife, and the outer edge
of the plantar border of the wall well rounded with the rasp. In the
base-wide and base-narrow standing positions the outer and inner walls
respectively become relatively long and induce the colt to assume a
still more abnormal position. The young and pliant pasterns may thus
become permanently twisted and distorted (see Figs. 183 and 184). In a
hoof that is becoming awry, restoring to the wall its proper level with
relation to the position of the limb will not only be invaluable in
ultimately producing a good hoof, but will improve the faulty position
of the limb. In exceptional cases, where the plantar border of some
section of the wall gives evidence of too rapid wear, the application
of a tip or of a half-shoe may be of benefit. Furthermore, we should
attempt to secure greater cleanliness by frequently and thoroughly
washing the hoofs and bedding with plenty of good straw.
[Illustration: FIG. 184.
Left front long pastern of a colt showing compression shortening of
outer half: _a_, transverse axis of upper articulation; _b_, transverse
axis of coronary joint, not parallel to upper axis.]
Too early shoeing of young horses is very injurious; it hinders the
development of the hoofs, and, furthermore, young horses when shod are
frequently seriously overworked and prematurely ruined. Moderate work
in the fields does not injure young horses, but for such service they
do not require shoes.
The unshod hoofs of older horses should be periodically rounded with a
rasp and the length of the walls regulated when, by reason of a lack of
exercise, proper wear has not taken place.
B. Care of Shod Hoofs.
Shod hoofs are exposed to many more injuries than are unshod hoofs,
because shoeing itself, although absolutely necessary to render horses
continuously serviceable upon hard streets, is injurious to the hoof,
since it to a greater or less extent prevents the physiological
movements of the different parts of the foot, interferes with the
circulation of the blood in the foot, slows the growth of the horn, and
brings about a gradual shrinking of the entire hoof.
In addition, there are the injurious consequences of stabulation. These
are _prevention of free movement_, _uncleanliness_ due to bad floors
and filthy bedding,—as, for example, peat moss and soiled straw,—and
_dryness_.
Continuous standing always contributes to contraction of the hoofs,
and this evil is greatly favored by dryness, which more particularly
affects the front hoofs. The hind hoofs receive sufficient moisture
from the animal’s manure. Poor floors, particularly those that are
uneven, tire the limbs. Accumulation of manure and the _careless_ use
of stationary sole-pads induce thrush of the frog.
The object of hoof nurture is to lessen or entirely remove all these
injurious consequences of shoeing and stabulation. It comprises,
therefore, not only the proper shortening of the hoofs every five to
six weeks, but careful attention to _cleanliness and moisture_. Both
are insured by dry straw and daily picking out and washing the hoofs.
Such measures will prevent thrush in the hind feet. If front hoofs
are washed once a day, sufficient moisture will penetrate the horn to
give it that degree of suppleness (elasticity) which is possessed by
an unshod hoof, and which contributes to a proper expansion of the
hoof when the body-weight is placed upon it. _In order to prevent a
hoof from again drying out_, the entire hoof should receive a thorough
application of an oil or ointment (hoof-salve). _The object of greasing
the horn is to prevent evaporation of the moisture that has penetrated
the horn._ Specially compounded hoof-salves are not necessary. Melted
horse-grease, pork-fat, or any other fat that is not rancid is
sufficient. Cosmoline is an excellent hoof-salve.
_Abundant_ but not excessive _exercise_ is more necessary than
anything else to the preservation of the health of the hoof. It aids
the circulation of blood within the foot, and, therefore, the growth
of the horn. Horses which perform hard, regular work have, as a rule,
better hoofs than those which stand the greater part of the time in the
stable. Poulticing hoofs with clay, bran, linseed-meal, or white-rock,
or standing them in water is unnecessary if they have had proper care,
but will sometimes be of benefit when the hoofs have been neglected,
and especially so for front hoofs. The latter are more exposed to
drying influences, and the shoes prevent the moistening process by
keeping the hoofs partially or completely removed from contact with the
earth. _Oiling alone is not sufficient to soften horn_, but must always
be preceded by permeation of the horn with water. =Oiling without first
cleansing the hoof is useless, because this soon produces a greasy
crust underneath which the horn is crisp and brittle.=
The surest sign of cleanliness of a hoof is the appearance of the
natural color of the horn, the latter appearing translucent even after
the hoof-ointment has been applied; therefore, blackened hoof-ointments
should not be used. When hoofs are exposed to too much moisture (muddy
roads, melting snow, etc.) an addition of wax or common yellow rosin to
the hoof-ointment is recommended to prevent too great softening of the
horn. _No hoof-ointment has any direct influence upon the growth of the
horn._
Inasmuch as it is a fact that the very best shoeing injures the hoof,
it is advisable to allow horses to go barefoot whenever it is possible.
This applies especially to horses that from any cause are thrown out
of service, presupposing, of course, that the nature of the hoofs will
allow them to go barefoot.
PART III.