LAMENESS IN THE FORE LEG.
Anatomo-Physiological Review of parts of the Fore Leg.
For supporting weight, whether the subject is at rest or in motion, the
bony column of the leg, together with attached ligaments, tendons and
muscles, is wonderfully well adapted by nature for the function which
they perform. The several bones which go to make up the supportive
portion of the leg, are so joined at their points of articulation, that
a minimum degree of strain is put upon each attachment.
The upper third of the scapula, with its cartilage of prolongation, is
sufficiently broad and flattened that it fits snugly against the thorax
without necessity for a complicated method of attachment--the clavicle
being absent, attachment is muscular.
Smith[5] has very aptly stated that:
"It seems quite legitimate to regard the muscular union between the
thorax and forelimb as a joint. There are no bones resting on each
other, no synovia; but where the scapula has its largest range of
movement there is a remarkable amount of areolar tissue, which renders
movement easy. The whole central area beneath the scapula and humerus
not occupied by muscular attachment, is filled with this easy-moving,
apparently gaseously distended, crepitant, areolar tissue over which the
fore legs glide on the chest wall as freely as if the parts were a
large, well lubricated joint."
The scapulohumeral articulation (shoulder joint) is an enarthrodial
(ball and socket) joint but because of its being held more or less
firmly against the thoracic wall by muscular and tendinous attachment,
and because a part of this attachment affords a means of support for the
body itself, there is no need for binding ligaments and movement is
possible in all directions even though restricted as to extent.
[Illustration: Fig. 2--Muscles of Left Thoracic Limb from Elbow
Downward; Lateral (External) View.
a, Extensor carpi radialis; g, brachialis; g', anterior superficial
pectoral; c, common digital extensor; e, ulnaris lateralis. (After
Ellenberger-Baum, Anat. für Künstler.) (From Sisson's "Anatomy of the
Domestic Animals").]
[Illustration: Fig. 3--Muscles of Left Thoracic Limb from Elbow
Downward; Medial (Internal) View.
The fascia and the ulnar head of the flexor carpi ulnaris have been
removed. 1, Distal end of humerus; 2, median vessels and nerve. (From
Sisson's "Anatomy of the Domestic Animals").]
Undue extension, (by extension is meant such movement as will cause the
long axis of two articulating bones to assume a position which
approaches or forms a straight line--opposite to flexion), of the
scapulohumeral joint is impossible while weight is borne, because of the
normally flexed position of the humerus on the scapula; whereas flexion,
beyond desirable limits, is inhibited by the biceps brachii (flexor
brachii or coracoradialis) muscle.
The distal end of the humerus, however, articulating with the radius and
ulna in a fashion that no support is lent by any sort of contact with
the body, is a ginglymus (hinge) joint and lateral motion, because of
the long transverse diameter of its articular portions, is easily
prevented by the medial and lateral ligaments (internal and external
ligaments). Flexion of this, the humeroradioulnar joint (elbow), is
restrained by the triceps brachii and extension is checked by the biceps
brachii (flexor brachii).
The carpal joint (erroneously called the knee joint), is composed of the
several carpal bones which interarticulate and, when taken as a group,
serve as a means of attachment and articulation for the radius and
metacarpal bones.
The transverse diameter of this joint is long, thus giving it contacting
surfaces that are sufficiently extensive to minimize the strain upon the
mesial and lateral ligaments (internal and external lateral common
ligaments). Motion is that of flexion and extension; slight rotation is
possible when the position is that of flexion. While supporting weight
the carpus is fixed in position by a slight dorsal flexion, but undue
dorsal flexion is prevented by the flexor muscles and tendons and
volar-carpal or annular ligament, together with the superior check
ligament.
The metacarpophalangeal articulation (fetlock joint), is a hinge joint
and its articular surfaces contact one another, with respect to their
having a long bearing surface from side to side, as do all ginglymus
(hinge) joints. Two common lateral ligaments bind the bones together.
While bearing weight, there is assumed a position of slight dorsal
flexion, undue flexion being checked by the inhibitory apparatus of the
joint--check ligaments, and their tendons and the suspensory ligament.
The inhibitory apparatus of the fetlock joint is materially reinforced
by the proximal sesamoid bones. Situated as they are, between the
bifurcating portions of the suspensory ligament and the posterior part
of the distal end of the metacarpus--with which they articulate--the
sesamoid bones serve to change the course of the branches of the
suspensory ligament in a manner that they give firm support to this
joint. Volar flexion is limited by the extensors of the phalanges.
[Illustration: Fig. 4--Sagital Section of Digit and Distal Part of
Metacarpus.
A, Metacarpal bone; B, first phalanx; C, second phalanx, D, third
phalanx; E, distal sesamoid bone; 1, volar pouch of capsule of fetlock
joint; 2, inter-sesamoidean ligament; 3, 4, proximal end of digital
synovial sheath; 5, ring formed by superficial flexor tendon; 6, fibrous
tissue underlying ergot; 7, ergot; 8, 9, 9', branches of digital
vessels; 10, distal ligament of distal sesamoid bone; 11, suspensory
ligament of distal sesamoid bone; 12, 12', proximal and distal ends of
bursa podotrochlearis. (From Sisson's "Anatomy of the Domestic
Animals").]
The first phalanx (os suffraginis) normally sets at an angle of about
50 to 55 degrees from a horizontal plane while weight is being
supported. Its distal end articulates with the second or median phalanx
(os corona) and forms the proximal interphalangeal (pastern or
suffraginocoronary) joint. This also, is a ginglymus joint, having but
slight lateral motion, and that only when it is in a state of flexion. A
rather broad articular surface--from side to side--exists here,
lessening the strain on the collateral ligaments somewhat. Dorsal
flexion is checked by the flexor tendons and dorsal ligaments. Volar
flexion is restrained by the extensor tendons.
The distal end of the second phalanx (os corona) has but slight lateral
motion and this is manifested principally when it is in a state of volar
flexion. Undue dorsal flexion is prevented by the deep flexor tendon
(perforans) and volar flexion is inhibited by the extensor of the digit
(extensor pedis). Thus it is seen, that when the leg is a weight-bearing
member, weight is supported by the bony framework whose constituent
parts are joined together by ligaments and tendons and each one of the
several bones articulates in such manner that the joint is locked. The
articular parts of bones rest upon or against an inhibitory apparatus,
and are slightly flexed, as in the carpus, or considerably flexed such
as in the fetlock joint when weight is being supported. In the first
instance, for example, the flexors of the carpus and the superior check
ligament assisted by the flexors of the phalanges constitute the
inhibitory apparatus.
It will be noted that provision for weight bearing is so arranged that
muscular energy is not required except in the matter of suspension of
the body between the scapulae and here tonic impulses only are necessary
to maintain an equilibrium[6], yet in every instance where weight is not
supported by bones, inelastic ligaments or tendinous structures relieve
the musculature of this constant strain. This explains the fact that
some horses do not lie in the stall, yet in spite of their constant
standing position, they are able to rest and sleep.
The student of lameness is interested in the function of the legs in the
rôle of supporting weight and as propelling parts, and not particularly
in the capacity of these members for inflicting offense or as weapons
of defense. Yet, in the exercise of their functions other than that of
locomotive appliances, injury often results, but usually it is the
recipient of a blow that suffers the injury, such as an animal may
receive upon being kicked. Therefore, we do not often concern ourselves
with strains or other injuries that the subject experiences as the
result of efforts put forth in kicking or striking. Where such injuries
occur, however, a diagnosis is established by making use of the
principles heretofore discussed.
As propelling members the front legs bear weight and are advanced
alternately when the horse is walking or trotting--in cantering this is
not so. When the normal subject travels in a straight line, at a walk or
a trot, the length of the stride is the same with the right and left
members. The stride of the right foot then, for example, is equally
divided by the imprint of the left foot, in the normal horse, when
traveling at a walk and in a straight line.
Shoulder Lameness.
This enigmatical term is frequently employed by the diagnostician when
he is baffled in the matter of definitely locating the cause of
lameness; when he has by exclusion and otherwise arrived at a decision
that lameness is "high up." Shoulder lameness may be caused by any one
or several of a number of conditions, e.g., fractures of the scapula or
humerus; arthritis of the shoulder or elbow joint; luxation of the
shoulder or elbow joint (rarely); injuries of muscles and tendons of the
region due to strains, contusions or penetrant wounds; paralysis of the
brachial plexus or of the prescapular nerve; involvement of lymph
glands; arterial thrombosis; metastatic infections; rheumatic
disturbances; and as the result of inflammation, infectious or
non-infectious occasioned by collar bruises. In some instances such
inflammation is due to the manner of treatment of collar injuries.
Therefore, when one considers the numerous and dissimilar possible
causes of shoulder lameness, it behooves the practitioner to become
proficient in diagnostic principles.
A principle which is elemental in the diagnosis of locomotory
impediment, is that lameness of the shoulder or hip is usually
manifested by more or less difficulty in swinging the affected member.
Swinging-leg-lameness, then, is usually present in shoulder affections.
In some instances lameness is mixed as in joint ailments, involvement of
the bicipital bursa (bursa intertubercularis), etc. In affections of the
extremity there exists supporting leg lameness. Consequently, we employ
this elemental principle, and, by a visual examination of the subject,
which is being made to travel suitably, one may decide that lameness is
either "high up"--shoulder lameness or, "low down"--of the extremity.
[Illustration: Fig. 5--Ordinary type of heavy sling.]
To make practical use of this principle, the examiner must be thoroughly
familiar with the anatomy of the various structures concerned in
advancing the leg--those which support weight as well as those concerned
both in weight bearing and swinging the member.
Fracture of the Scapula.
Etiology and Occurrence.--Fractures of the body of the scapula are of
infrequent occurrence in horses for the reason that protection is
afforded this bone because of its position. Its function, too, is such
that very unusual conditions are necessary to subject it to fracture.
The spine is occasionally broken due to blows such as kicks, etc., and
here frequently a compound fracture exists.
[Illustration: Fig. 6--A sling made in two parts so that horses may be
supported without use of central part or bodice. This sling is more
comfortable than is the ordinary style and is particularly useful in
cases that require a long period of this manner of confinement.]
Where fractures of the body of the scapula occur, heavy contusions have
been the cause as a rule, and serious injury is done the subject;
consequently, treatment of fracture of the body of the scapula is seldom
successfully practised. Fractures of the body of this bone resulting
from accidents not involving internal injury or other disturbances and
which would not seriously interfere with the vitality of the subject,
are not necessarily serious unless compound.
Fractures of the neck of the scapula are serious because of the fact
that there occurs displacement of the broken parts and perfect
apposition of the fractured ends is difficult, if not impossible.
Fractures that extend to the articular surface are very serious, and
complete recovery in such instances is practically impossible. The
cartilage of prolongation of the scapula is sometimes seriously involved
in certain cases of fistulous withers, and in some instances it has been
separated from its attachment to the rhomboidea muscles, and lameness
has resulted. In such instances, the upper portion of the scapula is
disjoined from all attachment, and with every movement the animal makes,
the scapula is moved back and forth. Complete recovery in such cases
does not occur.
Symptomatology.--Fractures of the scapular spine are ordinarily
readily recognized because there is usually visible displacement of the
broken part. Crepitation is also detected without difficulty.
In fractures of the body of the scapula where an examination may be made
before much swelling has taken place, and in subjects that are not
heavily muscled, one should have no difficulty in recognizing the
crepitation.
Fractures of the neck of the scapula are recognized by crepitation, by
passively moving the leg, but it is necessary to exclude fractures of
the humerus when one depends upon the finding of crepitation by this
means. However, unless undue swelling exists, the exact location of the
crepitation is recognized without serious difficulty.
Treatment.--The treatment of compound fractures of the scapular spine
consists in the removal of the broken piece of bone by way of a
cutaneous incision so situated that good drainage of the wound will
follow.
Simple fractures of the body of the scapula are best treated by placing
the subject in a sling, if the animal is halter broken, and enforcing
absolute quiet for a period of from three to six weeks. Splints or
similar appliances are not of practical value in scapular fractures.
Compound fractures of the scapula usually result from violence, which at
the same time does serious injury to adjacent structures, and it then
becomes necessary to administer an expectant treatment, observing
general surgical principles and providing in so far as possible for the
comfort of the patient.
Scapulohumeral Arthritis.
Anatomy.--The scapulohumeral joint is an enarthrodial (ball and
socket) joint wherein the ball or humeral articulating head greatly
exceeds in size the socket or glenoid cavity of the scapula. The
capsular ligament surrounding this joint is very large and admits of
free and extensive movement of the articulation. There exist no lateral
or common ligaments jointing the scapula and humerus as in other joints,
but instead the tendinous portions of muscles perform this function. The
principal ones which are attached to the scapula and humerus that act as
ligaments are the supraspinatus (antea-spinatus), infraspinatus
(postea-spinatus) biceps-brachii (flexor brachii) and subscapularis
muscles.
Etiology and Occurrence.--Inflammation of the scapulohumeral
articulation results from injuries of various kinds, including punctures
which perforate the joint capsule, bruises from collars, metastatic
infections and involvement as a result of direct extension of infectious
conditions situated near the joint.
Classification.--Acute arthritis may be septic or aseptic, and there
seems to be a remarkable tendency for recovery in cases of septic
arthritis involving this joint in the horse.
Chronic arthritis with destruction of articular surfaces and ankylosis,
is seldom observed. It is only in cases of severe injury, where the
articular portions of the bones are damaged at the time of infliction of
the injury, and where the articulation remains exposed for weeks at a
time, together with immobility of the parts because of attending pain,
that permanent ankylosis results.
Scapulohumeral arthritis may result then from _infections_, local or
metastatic; from _injuries_, such as contusions of various kinds; from
_wounds_, which break the surface structure or perforate the joint
capsule; or from _luxations_.
Infectious Arthritis.
Infectious arthritis of the scapulohumeral joint the result of local
causes other than produced by septic wounds, seldom causes serious
inconvenience to the subject. Where such occurs, however, there is
manifested mixed lameness and complete extension of the extremity is
impossible. Local swelling is present and manifestations of pain are
evident upon palpation of the affected area.
Treatment.--During the first stage of the infection, local
applications, hot or cold, are indicated. A hot poultice of bran or
other suitable material contained within a muslin sack, may be supported
by means of cords or tapes which are passed over the withers and tied
around the opposite fore leg. Such an appliance may be held in position
more securely by attaching it to the affected member. Following the
acute stage of such an infection, any local counter-irritating
application or even a vesicant is in order.
Where abatement of the infectious process does not take place, and
suppuration of the structures in the vicinity of the joint occurs, it is
necessary to provide drainage for pus. In some cases of strangles, for
instance, large pus cavities are formed and drainage is imperative.
However, metastatic inflammation of this joint is seldom observed except
in cases of strangles. The animal should be kept perfectly quiet until
recovery has taken place.
Injuries.
Injuries to the scapulohumeral joint may be the result of kicks, runaway
accidents or bruises from the collar, and there may result, because of
such injuries, reactionary inflammation which will vary in intensity
from the mildest synovitis to the most severe arthritis, causing more or
less lameness.
Treatment.--The general plan of treatment in this form of arthritis is
the same as has been outlined under the head of infectious arthritis,
with the exception that there is seldom occasion to provide for drainage
of pus.
Wounds.
Wounds which cause a break of the skin and fascia overlying the
scapulohumeral joint are usually of little consequence, unless the blow
is of sufficient force to directly injure the articulation, and in such
cases, the treatment of the injury along general surgical principles,
such as cleansing the area, providing drainage for wound secretion, and
the administration of suitable dressing materials such as antiseptic
dusting powder, is all that is required for the wound. The symptoms
manifested by the subject in such cases are the same as have been
discussed heretofore and merit no special consideration.
Prognosis.--Unless very serious injury be done the articular portions
of the scapula or the humerus, resulting in the destruction of the
capsular ligament, prognosis is entirely favorable.
Open Joint.--Where the capsular ligament is perforated and the
condition becomes one of open joint, then a special wound treatment
becomes necessary. The surface of the skin is first freed from all hair
and filth in the vicinity of the wound. The wound proper is cleared of
all foreign material either by clipping with the scissors, curetting or
mopping with cotton or gauze pledgets. The whole exposed wound surface
as well as the interior of the joint cavity, if much exposed, is
moistened with tincture of iodin. Subsequent treatment consists in a
local application of a desiccant dusting powder, which should be applied
five or six times daily. The composition of the powder should be such as
to permit of its liberal use, thereby affording mechanical protection to
the wound as well as exerting a desiccative effect. Equal parts of boric
acid and exsiccated alum serve very well in such cases.
Animals suffering from open joints of this kind should be confined in a
standing position, preferably in slings, and kept so confined for three
or four weeks. Since they usually bear weight upon the affected member,
there is no danger of laminitis resulting.
Luxation of the Scapulohumeral Joint.
Because of the large humeral head articulating as it does with a
glenoid cavity, scapulohumeral luxations are very rare in the horse.
According to Moller[7], luxation is generally due to excessive flexion
of the scapulohumeral joint. In such cases the head of the humerus is
displaced anterior to the articular portion of the scapula and remains
so fixed.
Symptoms.--Complete luxation of the scapula is recognized because of
immobility of the scapulohumeral joint and of the abnormal position of
the head of the humerus, which can be recognized by palpation, unless
the swelling be excessive. Immobility of the scapulohumeral joint is
noticeable when one attempts to passively move the parts.
Treatment.--Reduction of the luxation is effected by making use of the
same general principles that are employed in the reduction of all
luxations, and they are--the control of the animal so that the
manipulations of the operator are not antagonized by muscular
contraction, which is best accomplished by anesthesia; placing the
luxated bones in the position which they have taken to become unjointed;
and then making use of force which is directed in a manner opposite to
that which has effected the luxation.
In a forward luxation of this kind, the operator should further flex the
humerus, and while it is in this flexed position, force is exerted upon
the articular head of this bone, and it is pushed downward and backward
into its normal position.
After-care consists in restriction of exercise and, if necessary,
confining the subject in a sling and the application of a vesicant over
the scapulohumeral region.
Inflammation of the Bicipital Bursa.
(Bursitis Intertubercularis.)
Anatomy.--There is interposed between the tendon of the biceps brachii
(flexor brachii) and the intertubercular or bicipital groove a heavy
cartilaginous pad, which is a part of the bursa of the biceps brachii.
This synovial bursa forms a smooth groove through which the biceps
brachii glides in the anterior scapulohumeral region. Great strain is
put upon these parts because the biceps brachii is the chief inhibiting
structure of the scapulohumeral articulation--the one which prevents
further flexion of the humerus during weight bearing. Passing, as it
does, over two articulations, the biceps brachii has a somewhat
complicated function, being a flexor of the radius and an extensor of
the humerus. Thus it is seen, the biceps brachii is a weight bearing
structure, as well as one that has to do with swinging the leg.
Etiology and Occurrence.--Because of the exposed position of the
bicipital bursa (bursa-intertubercularis) it is occasionally injured.
Blows and injuries received in runaway accidents do serious injury to
the bursa and because of the peculiar and important part it plays during
locomotion, serious injuries are not likely to resolve, and too often
chronic lameness results. It is to be noted that the tendon of the
biceps brachii (flexor brachii) is always involved in cases of
inflammation of the bicipital bursa, and according to the late Dr.
Bell[8] strain of the biceps brachii is a frequent cause of lameness in
city horses, more frequent than is generally supposed.
Pathological Anatomy.--More or less destruction of the cartilaginous
portion of the bursa, sometimes involving the tendinous portion of the
biceps, takes place and, according to Moller, in some instances there
occurs ossification of the tendon. Autopsies in some old horses reveal
the presence of erosions of cartilage and hyperthrophy of the inflamed
parts.
Symptoms.--In acute inflammations, there is always marked lameness.
This is manifested to a greater degree when the subject advances the
affected leg. There is incomplete advancement of the member; the toe is
dragged when the horse is made to walk and the foot kept in a position
posterior to the opposite or weight bearing foot while the subject is at
rest. Lameness is disproportionate to the amount of local manifestation
in the way of heat, swelling and pain that is to be recognized on
palpation. In fact, in some cases so much pain attends the condition
that no weight is borne by the affected member, and when compelled to
walk, the subject hops on the sound leg.
Chronic inflammation of the bicipital bursa is occasionally met with
wherein both members are affected. Because of the nature of the
structures involved, when inflamed, chronic inflammation is a more
frequent termination than is complete recovery. Bilateral affections are
seen in horses that are driven for years, regularly at a fast pace on
paved streets. In such cases, the gait is stilted, that is, there is
incomplete advancement of both members and, of course, the period of
weight bearing is correspondingly shortened; hence the short strides.
In chronic cases, little if any evidence of inflammation is to be
detected by digital manipulation of the parts. If flinching occurs, one
is often unable to interpret the manifestation as to whether it is due
to inflammation or not.
There is no marked "warming out" in this condition, and animals are
nearly as lame after having been driven a considerable distance as when
started, although the lameness is not as a rule very great.
Treatment.--In very painful cases acute inflammation is treated by
employing cold applications during the initial stage. Cracked ice when
contained in a suitable sack may be held in contact with the affected
part and the pack is supported by means of cords or tapes as suggested
in the discussion on treatment of scapulohumeral arthritis on page 66.
Later, hot applications may be employed to good advantage.
In the course of ten days or two weeks, if the acute painful condition
has entirely subsided, vesication is indicated. The ordinary mercury and
cantharides combination does very well. Depending upon the course taken
in any given case, one is guided in the treatment employed. If prompt
resolution comes to pass, the subject may be given free run at pasture
after three or four weeks confinement in a box stall. If, however, the
case does not progress in a prompt and satisfactory manner, absolute
quiet must be enforced for six weeks or more. Repeated blistering is
beneficial, although it is doubtful if firing is of sufficient benefit
in the average chronic case of intertubercular bursitis to justify the
punishment which this form of treatment inflicts, unless infliction of
pain is the thing sought, to enforce repose in restless subjects.
Patients are best given a long rest at pasture and returned to work for
two or three months after an acute attack of inflammation of the bursa,
lest the condition become chronic. When due consideration is given the
pathology of such cases, the frequent unsatisfactory termination under
the most careful treatment, is readily understood.
Contusions of the Triceps Brachii.
(Triceps Extensor Brachii: Caput Muscles.)
Anatomy.--The triceps brachii is the principal structure which fills
the space between the posterior border of the scapula and the humerus.
The several heads originate for the most part on the border of the
scapula, the deltoid tuberosity of the humerus and the shaft of the
humerus. Insertion of this large muscular mass is effected by means of
several tendons to the olecranon. A synovial bursa is situated
underneath the tendinous attachment of the posterior portion of the
triceps brachii--the long head or caput magnum.
The function of the triceps as a whole is to flex the shoulder joint and
extend the forearm. The triceps brachii is the chief antagonist of the
biceps brachii.
Etiology and Occurrence.--Owing to the exposed position of this
structure, it is not infrequently contused, the result of falls, kicks
and other injuries. The function of the triceps is such that it becomes
strained upon rare occasions when a horse resists confinement of
restraint in such manner that the parts are unduly tensed in
contraction. This sort of resistance may stretch the radial nerve or its
branches in a way that paralysis results. A condition known as "dropped
elbow" is described by Henry Taylor, F.R.C.V.S., in the Veterinary
Record[9], wherein a two-year-old colt while resisting confinement was
so injured.
The triceps group because of its convenient location, constitutes the
site for hypodermic injection of drugs and biologic agents, with some
practitioners; and as a result, more or less inflammation may occur. The
author has observed and treated some twenty cases where an intensely
painful infectious inflammation of the triceps brachii was caused by
the intramuscular injection of a caustic solution by a cruel and
unscrupulous empiric, whose object was to increase his practice.
Symptomatology.--As the triceps brachii is not particularly taxed
during weight bearing in the subject at rest, there may be no unnatural
position assumed during inflammation of the triceps. More or less
swelling and supersensitiveness is always present, however, and great
care and discrimination must be exercised in digital manipulation of the
triceps region because many animals are normally sensitive to palpation
of these parts. It is sometimes difficult to correctly interpret the
true state of conditions because of this peculiarity.
There is always swinging-leg-lameness, which is accentuated when the
subject is urged to trot. Where symptoms are pronounced, it is
unnecessary to cause the subject to move at a faster pace than at a walk
to recognize the condition. The forward stride is shortened and in
extremley painful conditions, no attempt is made to extend the leg. It
is simply carried _en une piéce_--flexion of the shoulder and elbow
joints is carefully avoided.
Treatment.--During the early stage of inflammation, hot or cold
applications are beneficial. Long continued use of moist
heat--fomentations--allays pain and stimulates resolution. Keeping in
contact with the painfully swollen parts a suitable bag filled with
bran, which can be moistened at intervals with warm water, constitutes a
practical and easy means of treatment. By employing this method, one is
more likely to succeed in having his patient properly cared for, in that
less work is entailed than if hot fomentations are prescribed.
After the acute and painful stage has subsided, a stimulating liniment
is of benefit. The subject should be kept within a comfortable and roomy
box stall for a sufficient length of time to favor prompt resolution.
Wild and nervous subjects, if not so confined, will probably overexert
the affected parts if allowed the freedom of a paddock or pasture.
Where the inflammation becomes infective, surgical interference is
necessary. The prompt evacuation of pus, with adequate provision for
wound discharge, should be attended to before extensive destruction of
tissue takes place. Resolution is prompt as a rule in such cases because
of the vascularity of the structures and the ease with which proper
drainage may be effected. No special after-care is necessary if drainage
is perfect, except that one should avoid injecting the wound cavity with
aqueous solutions unless it be absolutely necessary to cleanse such
cavity, and then it is best to swab the wound rather than to irrigate it
freely.
Shoulder Atrophy.
(Sweeny or Swinney)
No satisfactory consideration of the pathogeny of this condition is
recorded, but practitioners have long distinguished between muscular
atrophies which are apparently caused without doing serious injury to
nerves and muscular atrophy which seems to be due to nerve affection. In
the first instance, recovery when proper attention is given, is prompt;
whereas, in the latter, regeneration of the wasted tissues requires
months in spite of the best sort of treatment.
The parts more frequently affected are the supra- and infrascapularis
(antea- and posteaspinatus) muscles. But in some cases the triceps group
is involved; however, this occurs in unusual and chronic affections. No
doubt, these chronic cases are due to suspended innervation and are not
to be classed with the ordinary case of atrophy of the abductor muscles
of the humerus (supra- and infraspinatus) as in the usual case of
"sweeny."
Occurrence.--Shoulder atrophy such as the general practitioner
commonly meets with, is an affection, more often seen in young animals
and it seems to be due to injuries of various kinds which contuse the
muscles of the shoulder. Ill-fitting collars and pulling in a manner
that there occurs side draft with unusual strain on the muscles of one
side of the neck and shoulder, seem to be the more frequent causes of
this trouble. Blows such as are occasioned by kicks and falls frequently
result in atrophy of shoulder muscles.
Course.--In some cases a rapidly progressive atrophy characterizes the
case and lameness and atrophy appear at about the same time. The
affection in such instances does not recover spontaneously but
constitutes a condition which requires prompt and rational treatment so
that function may be fully restored to the parts involved.
Occasionally one may observe cases where there is but slight atrophy;
where the disease progresses slowly and atrophy is not extensive or
marked. In vigorous young animals that are left to run at pasture when
so mildly affected, spontaneous recovery occurs.
Symptomatology.--Lameness is the first manifestation of shoulder
atrophy, and in many cases where lameness is slight, the veterinarian
may fail to discover the exact nature of the trouble if he is not very
proficient as a diagnostician of lameness or if he is careless in taking
into consideration obtainable history, age of the subject, etc. Because
of the fact that the average layman believes that practically every case
of fore-leg lameness wherein it is not obvious that the cause is
elsewhere, is due to a shoulder affection of some kind, we may be too
hasty in giving the client assurance that no "sweeny" exists. In some of
these cases where a diagnosis of "shoulder lameness" has been made and
the client has been assured that no sweeny exists, the patient is
returned in about a week and there is then marked atrophy of one or both
of the spinatus muscles.
A mixed type of lameness characterizes this affection, and in the
average case there exists little evidence of local pain. The salient
points in recognizing the condition are a consideration of history if
obtainable; age of the subject; finding slight local soreness, by
carefully manipulating the muscles which are usually involved; noting
the character of the lameness if any is present; and where atrophy is
evident, of course, the true condition is obvious.
Treatment.--Subcutaneous injections of equal parts of refined oil of
turpentine and alcohol, with a suitable hypodermic syringe, is a
practical and ordinarily effective treatment. From five to fifteen cubic
centimeters (the quantity varies with the size of the animal), of this
mixture is injected into the atrophied parts at different points, taking
care to introduce only about one to two cubic centimeters at each point
of injection. The syringe should be sterile and, needless to say, the
site of injections must be surgically clean.
Other agents, such as tincture of iodin, solutions of silver nitrate,
saline solutions and various more or less irritating preparations have
been employed; but in the use of these preparations one may either fail
to stimulate sufficient inflammation to cause regeneration to take
place, or infection is apt to occur. Where suppuration results, surgical
evacuation of pus must be promptly effected else large suppurating
cavities form.
The employment of setons constitutes a dependable method of treatment of
shoulder atrophy, but because of the attendant suppurative process which
inevitably results, this method is not popular with modern surgeons and
is a last resort procedure.
After-care.--Regular exercise such as the horse usually takes when at
pasture, is very helpful in treating atrophy, and in some cases it has
been found that no reasonable amount of irritation would stimulate
muscular regeneration; but by later allowing patients to exercise at
will, recovery took place in a satisfactory manner. No special attention
is ordinarily necessary.
Paralysis of the Suprascapular Nerve.
Anatomy.--The suprascapular (anterior scapular) nerve, a small branch
of the brachial plexus, is given off from the anterior portion of this
plexus. The nerve rounds the anterior border of the neck of the scapula,
passing upward and backward under the supraspinatus (antea-spinatus)
muscle and terminating in the infraspinatus (postea-spinatus) muscle.
Etiology and Occurrence.--As the result of direct injury to this nerve
by contusion such as may be received in runaway accidents, collar
bruises, especially collar bruises in young horses that are not
accustomed to pulling and that walk in a manner to cause side draft,
injury to the nerve occurs, and partial or complete paralysis
supervenes. Some writers state that it may be produced by confining an
animal in recumbency, with the casting harness. The common cause of
paralysis or paresis of this nerve in cases such as one observes in
country practice, is bruises from the collar in colts that are put to
heavy farm work or where ill fitting collars are used.
Symptomatology.--With partial or complete suspension of function of
the suprascapular nerve there results enervation of the supraspinatus
and infraspinatus muscles. Since these muscles act as external lateral
ligaments of the scapulohumeral joint, when they are incapacitated,
there naturally follows more or less abduction of the shoulder when
weight is borne.
In extreme cases, as soon as the ailing animal is caused to support
weight with the affected member, the joint is suddenly thrown outward in
a manner that the average layman at once concludes that there must be
scapulohumeral luxation, and the veterinarian receives a call to see a
case wherein the "shoulder is out of place." There exists, however, no
luxation in such cases.
If serious injury is done the nerve so that it undergoes degenerative
changes, there will result atrophy of the muscles that derive their
nerve supply from the suprascapular nerve.
[Illustration: Fig. 7--Paralysis of the suprascapular nerve of the left
shoulder]
Treatment.--During the first few days following injuries which result
in this form of paralysis, it is well to keep the subject inactive, and
if much inflammation of the injured structures contiguous to the nerve
exists, the application of cold packs is beneficial. Later, as soon as
acute inflammation has subsided, vesication of a liberal area around the
anteroexternal part of the scapulohumeral joint and over the course of
the suprascapular nerve, will stimulate recovery in favorable cases. As
a rule, in mild cases, the subject is in a condition to return to work
in two or three weeks.
Radial Paralysis.
Described under the titles of "Radial Paralysis" and "Brachial
Paralysis," there is to be found in veterinary literature a discussion
of conditions which vary in character from the almost insignificant form
of paresis to the incurably affected conditions wherein the whole
shoulder is completely paralyzed.
When one considers the anatomy of the brachial nerve plexus and the
distribution of its various branches, the location of this plexus and
its proximity to the first rib, and the inevitable injury it must suffer
in fracture of this bone, together with the inaccessibility of the
plexus, it is not strange that a correct diagnosis of the various
affections of the brachial plexus and the radial nerve is often
impossible until several days or weeks have passed. And, in some
instances, diagnosis is not established until an autopsy has been
performed. Here, too, we fail to find cause for paralysis in some rare
instances.
Anatomy.--The radial nerve is a large branch of the brachial plexus
and is chiefly derived from the first thoracic root of the plexus and is
here situated posterior to the deep brachial artery. It is directed
downward and backward under the subscapularis and teres major muscles,
rounding the posterior part of the humerus, and passing to the anterior
and distal end of the humerus, it finally terminates in the anterior
carpal region. The radial nerve supplies branches to the three heads of
the triceps brachii, to the common and lateral extensors of the digit
and also to the skin covering the forearm.
Etiology and Occurrence.--Nothing definite is known about the cause of
some forms of radial paralysis. However, radial paralysis is encountered
following injury to the nerve occasioned by its being stretched, as in
cases where the triceps brachii is unduly extended in restraining
subjects by means of a casting harness. Berns[10] states that in
confining horses on an old operating table where it was necessary to
draw the affected foot forward twenty-four to thirty-six inches in
advance of its fellow, which was secured in a natural vertical
position, radial paralysis of a mild form was of frequent occurrence.
Country practitioners, in restraining colts by casting with harness or
ropes, occasionally observe a form of paresis wherein the radial nerve
suffers sufficient injury that there is caused a temporary loss of
function of the triceps brachii. Such cases recover within three or four
days and are not a true paralysis, but nevertheless constitute
conditions wherein normal nerve function is temporarily suspended.
[Illustration: Fig. 8--Radial paralysis.]
Symptoms.--Immediately subsequent to injuries which involve the radial
nerve, there is manifested more or less impairment of function.
Remembering the structures supplied by the radial nerve and its
branches, one can readily understand that there should occur as
Cadiot[11] has stated:
In complete paralysis, the joints of the affected limb with the
exception of the shoulder are usually flexed when the horse is
resting. In consequence of loss of power in the triceps and
anterior brachial muscles, the arm is extended and straightened on
the shoulder, the scapulohumeral angle is open, and the elbow
depressed. The forearm is flexed on the arm by the contraction of
the coracoradialis (biceps brachii), while the metacarpus and
phalanges are bent by the action of the posterior antibrachial
muscles. The knee is carried in advance, level with, or in front
of, a vertical line dropped from the point of the shoulder. The
hoof is usually rested on the toe, but when advanced beyond the
above mentioned vertical line, it may be placed flat on the ground,
the joints then being less markedly bent. When the limb as a whole
is flexed, it may be brought into normal position by thrusting back
the knee with sufficient force to counteract the action of the
flexor muscles.
[Illustration: Fig. 9--Merillat's method of fixing carpus in radial
paralysis. Courtesy, Alex. Eger.]
When made to walk, the animal being unable to exert muscular action with
the paralyzed structures, limply carries the member as a whole, and
there is shortening of the anterior portion of the stride. There being
loss of function of the triceps brachii, it is impossible for the
subject to straighten the leg in the normal position for supporting
weight; therefore, any attempt to bear weight results in further
flexion of the affected member and the animal will fall if the body is
not suddenly caught up with the sound leg.
Differential Diagnosis.--In making examination of these cases, one can
exclude fracture by absence of crepitation and usually, also, swelling
is absent in radial paralysis. In a typical case of radial paralysis,
the affected leg can sustain its normal share of weight if placed in
position, that is, if the carpal joint is extended in such manner that
the leg is positioned as in its normal weight-bearing attitude. In
brachial paralysis, whether due to fracture of the first rib or to other
serious injury, it is impossible for the subject to support weight with
the affected member even when it is passively placed in position.
No difficulty is ordinarily experienced in differentiating radial
paralysis from muscular injuries to the triceps; yet, in some cases of
"dropped elbow," it is necessary to observe the progress of the case for
ten days or two weeks before one can positively establish a diagnosis.
Quoting Merillat[12]: "When, after four weeks, there is no
amelioration of the paralysis, the muscles have atrophied, and the
patient has become emaciated from pain and discomfort, the
diagnosis of brachial paralysis with fracture of the first rib may
then be announced."
Prognosis.--When no complete paralysis of the brachial plexus or no
fracture of the first rib exists, the majority of cases recover
completely in from ten days to six weeks. Some writers claim that
recoveries occur in ninety per cent of cases when conditions are
favorable.
Treatment.--When incomplete radial paralysis exists, little needs be
done except to allow the subject moderate exercise and to provide for
its comfort. Local applications, stimulative in character, are
beneficial, and the internal administration of strychnin is indicated.
In the cases where weight is not supported without the affected leg
being passively placed in position, it is necessary to provide for the
subject's comfort in several ways.
Mechanical appliances such as braces of some kind in order to keep the
affected leg in a position of carpal extension, constitute the essential
part of treatment. The leg is supported in such a manner that flexion of
the carpus is impossible. Due regard is given to prevent chafing or
pressure necrosis by contact of the skin with the braces--this may be
done by bandaging with cotton. The supportive appliance is kept in
position for ten days or two weeks. At the end of this time the brace
may be removed and the subject given a chance to walk, and improvement,
if any exists, will be evident. When there is manifested an amelioration
of the condition, moderate daily exercise and massage of the affected
parts are helpful.
Should the subject be seriously inconvenienced by the application of a
brace or other supportive appliances, it is necessary to employ slings.
Further, if weight is supported entirely by the unaffected member,
laminitis may supervene if a sling is not used.
Thrombosis of the Brachial Artery.
Thrombosis of the brachial artery or of its principal branches is of
very rare occurrence in horses.
Etiology.--Partial or complete obstruction of arteries (brachial or
others) occurs as the result of direct injury to the vessel wall from
compression and tension of muscles and resultant arteritis; lodging of
emboli; and parasitic invasion of vessel walls causing internal
arteritis.
Symptomatology.--If sufficient collateral circulation exists to supply
the parts with blood, no inconvenience is manifested while the subject
is at rest. Where the lumen of the affected vessel is not completely
occluded, there may be no manifestation of lameness when the ailing
animal is moderately exercised. Consequently, the degree of lameness
depends upon the extent of the obstruction to circulation; and,
likewise, the course and prognosis depend upon the character and extent
of such obstruction.
In severe cases, lameness is markedly increased by causing the animal to
travel at a fast pace for only a short distance. There are evinced
symptoms of pain, muscular tremors and sudation, but the affected member
remains dry and there is a marked difference of temperature between the
normal areas and the cool anemic parts. When the subject is allowed to
rest, circulation is not taxed, and there is a return to the original
and apparently normal condition, only to recur again with exertion. This
condition characterizes thrombosis.
Treatment.--In these cases, little if any good directly results from
any sort of treatment in the way of medication. Absolute rest is thought
to be helpful. Potassium iodid, alkaline agents such as ammonium
carbonate and potassium carbonate, have been administered. Circulatory
stimulants also have been given, but it is doubtful if any good has come
from medication.
Fracture of Humerus.
The shaft of the humerus, protected as it is by heavy muscles, is not
frequently fractured; and fractures of its less protected parts, as for
example, the head, are complicated in such manner that resultant
arthritis soon constitutes the more serious condition.
As a result of falls on frozen ground, kicks or any other form of heavy
contusion, the humerus is occasionally broken. It is rarely fractured
otherwise. Because of the force of contusions usually required to effect
humeral fracture, the manner in which the bone is broken, with respect
to direction, is variable. Often oblique fractures exist and
occasionally there occurs multiple fracture. In addition to the
ordinarily serious nature of the fracture itself, there is always much
injury done the adjoining structures.
Symptomatology.--Mixed lameness and manifestation of severe pain
characterize this affection. Considerable swelling which increases, in
some cases for a week or more, is to be observed. Crepitation is readily
detected, if pain and swelling is not too great to prevent passive
movement of the member. Where intense pain is not manifested, because of
manipulation, one may abduct the extremity and thereby occasion distinct
crepitation; but when it is possible to recognize crepitation by holding
the hand in contact with the olecranon while the animal is made to walk,
this method is to be preferred, if the subject can move without serious
difficulty. The pathognomonic symptom here is recognition of
crepitation, but this may be very difficult to recognize in fracture of
condyles, and in such instances, a careful examination is necessary.
Gentle manipulation in a manner that pain is not aggravated will tend to
inspire confidence on the part of the subject and relaxation of muscles
will enable the operator to detect crepitation.
Course and Prognosis.--Because of the direction of the long axis of
the humerus, with relation to the bony column of the extremity, it is
obvious that any lateral movement of the leg tends to rotate the shaft
of this bone. In fractures of the shaft of the humerus, then, it is
apparent that immobilization is very difficult if at all possible.
The proximity to the axillary lymph glands makes for easy dissemination
of infection when the contused musculature becomes infected. The
adjacent brachial nerve plexus is so very apt to become involved, if not
actually injured at the time fracture occurs, that paralysis is a
probable complication. Consequently, it is logical to reason that
because of the many possible serious complications, such as shock,
occasioned by the injury and the distress and pain which this accident
produces, recovery must be the exception in fracture of the humerus.
However, recoveries do take place and in addition to the reported
recoveries by Liautard, Moller, Stockfleth, Lafosse, Frohner and others,
we have instances cited by American practitioners where cases resulted
in recovery. Thompson[13] reports a good recovery in a 1600-pound mare
where there existed an oblique fracture of the humerus. This mare was
kept in slings for eight weeks. Walters[14] reports complete recovery in
humeral fracture in a foal three days old. The only treatment given was
the application of a pitch plaster from the top of the scapula to the
radius. The colt was kept in a comfortable box stall and in about four
weeks regained use of the leg. Complete recovery eventually resulted. In
the experience of the author, recovery has not occurred in humeral
fractures.
Treatment.--When animals are not aged and of sufficient value to
justify treatment, they are best supported in a sling, if halter broken.
If subjects are nervous, wild and unbroken, it is possible to employ the
sling, if care is given to train the animal to this manner of restraint.
The presence of an attendant for a day or two will reassure such
subjects so that even in these cases it may be practicable to employ the
sling.
Braces and other mechanical appliances intended to immobilize the parts
are not of practical benefit in the horse. Unlike the dog, the horse as
yet has not been successfully subjected to tolerating rigid braces for
the shoulder and hip.
Everything possible must be done that will make for the patient's
comfort. If the subject turns out to be a good self nurse, and the
nature of the fracture is such that practical apposition of the broken
ends of bone may be maintained, recovery will occur in some cases.
Inflammation of the Elbow.
(Arthritis.)
Affections of this articulation other than those which are produced by
traumatism are rare. This joint has wide articular surfaces, and
securely joined as they are by the heavy medial and lateral ligaments
(internal and external lateral ligaments), luxation is practically
impossible. When luxation does occur, irreparable injury is usually
done. Castagné as quoted by Liautard[15], reports a case of true
luxation of the elbow joint in a horse where reduction was effected and
complete recovery took place at the end of twenty-five days. This is an
unusual case. The average practitioner does not meet with such
instances.
Anatomy.--The condyles of the humerus articulate with the glenoid
cavities of the radius and a portion of the ulna. Two strong collateral
ligaments pass from the distal end of the humerus to the head of the
radius. The capsular ligament is a large, loose membrane which encloses
the articular portion of the humerus with the radius and ulna and also
the radioulnar articulation. It is attached anteriorly to the tendon of
the biceps brachii (flexor brachii). The capsule extends downward
beneath the origin of these digital flexors. This fact should be
remembered in dealing with puncture wounds in the region, lest an error
be made in estimating their extent and an open joint be overlooked at
the initial examination.
Etiology and Occurrence.--Exclusive of specific or metastatic
arthritis, which is seldom observed except in young animals,
inflammation of the elbow joint is usually caused by injury. This
articulation is not subject to pathologic changes due to concussion or
sprains as occasioned by ordinary service, but is frequently injured by
contusion from falls, blows from the wagon-pole and kicks. Wounds which
affect the elbow joint, then, may be thought of in most cases, as
resultant from external violence. They may be contused wounds or
penetrant wounds. Sharp shoe-calks afford a means of infliction of
penetrant wounds which may occasion open joint and infectious arthritis.
Classification.--A practical manner of classifying inflammation of the
elbow is on an etiological basis. Eliminating the forms of elbow
inflammation, such as are caused by metastatic infection and other
conditions which properly belong to the domain of theory of practice, we
may consider this affection under the classification of _contusive
wounds_ and _penetrative wounds_.
Symptomatology.--Any injury which is of sufficient violence to
occasion inflammation of the elbow causes marked lameness and
manifestation of pain. The degree of lameness and distress manifested by
the subject, depends upon the nature and extent of the involvement. A
contusion suffered as the result of a fall, which occasions a
circumscribed inflammation of the structures covering this joint and
where little inflammation of the articulating parts exists, marked
evidence of pain and lameness might be absent. On the other hand, if a
true arthritis is incited, there will be evident distress manifested,
such as hurried respiration, accelerated pulse, inappetence, mixed
lameness, local evidence of inflammation and particularly marked
supersensitiveness of the affected parts. Considering these two extremes
of manifested distress and injury, one may readily conclude that in the
frequently seen case, wherein contusion has occasioned a moderate
degree of injury, prognosis is favorable and recovery ordinarily
follows in the course of a few weeks' treatment.
In cases of arthritis due to penetrative wounds (because of the
important function of this joint and its large capsule, which when
inflamed discharges synovia in a manner that closure of such an open
joint is seldom possible) a very grave condition results.
Treatment.--Inflammation of the elbow, such as is frequently seen in
general practice where horses are turned out together and exposed to
kicks and other injuries, yields to treatment readily, if an open joint
does not exist.
Hot packs supported in contact with the elbow and kept around the
inflamed articulation for a few days, materially decrease pain and tend
to reduce inflammation. The subject must be kept quiet in a comfortable
stall and, if necessary, a sling used. Where it is impossible for the
animal to support much weight with the injured member the sling should
be employed.
As inflammation abates, which it does in the course of from one to three
weeks in uncomplicated cases, the subject may be allowed the freedom of
a comfortable box stall. Vesication of the parts is in order, and this
may be repeated in the course of two weeks, if it is deemed necessary.
Penetrative wounds resulting in open joint are not treated with success
as a rule, and because of the handicap under which veterinarians labor,
methods of handling such cases, where large, important articulations are
affected, are not being rapidly improved. Prognosis is usually
unfavorable, and for humane and economic reasons, animals so affected
should be destroyed.
Ordinary wounds of the region of the elbow are treated along general
lines usually employed. They merit no special consideration, except that
it may be mentioned that with such injuries concomitant contusion of the
parts occasions injury that does not recover quickly.
Fracture of the Ulna.
Etiology and Occurrence.--Fractures of the ulna in the horse are not
common in spite of the exposed position of the olecranon. This bone when
broken, is usually fractured by heavy blows and any form of ulnar
fracture is serious because of its function and position in relation to
the joint capsule. Transverse fractures do not readily unite because of
the tension of the triceps muscles, which prevent close approximation of
the broken ends of the bone.
Thompson[16], however, reports a case of transverse simple fracture of
the ulna in a mare, the result of a kick, in which complete recovery
took place. He kept the subject in a sling for six weeks and then
allowed six months rest.
Symptomatology.--The position assumed by a horse suffering from a
transverse fracture of the ulna, is similar to that in radial paralysis.
Crepitation may be detected by manipulating the parts, and in some
instances of fracture of the olecranon, there occurs marked displacement
of the broken portions of the bone. Lameness is intense and the parts
are swollen and supersensitive. The capsular ligament of the elbow joint
is usually involved in the injury because fracture of the ulna may
directly extend within the capsular ligament. In such cases, there is
synovitis, and later arthritis causes a fatal termination.
Treatment.--The impossibility of applying a bandage in any way to
practically immobilize these parts in fracture of the ulna, prevents our
employing bandages and splints. Therefore, one can do little else than
to put the patient in a sling and try to keep it quiet and as nearly
comfortable as circumstances allow.
Fracture of the Radius.
Etiology and Occurrence.--From heavy blows received such as kicks,
collision with trees or in falls in runaway accidents, the radius is
occasionally fractured. In very young foals, fracture of the radius, as
well as of the tibia and other bones, results from their being trampled
upon by the mother.
Symptomatology.--Excepting in some cases of radial fracture of foals
where considerable swelling has taken place, there is no difficulty in
readily recognizing this condition. The heavy brachial fascia materially
contributes to the support of the radius, and in cases where swelling
is marked, crepitation may not be readily detected. In fact, a
sub-periosteal fracture may exist for several days or a week or more and
then, with subsequent fracture of the periosteum, crepitation and
abnormal mobility of the member are to be recognized. In such cases, the
subject will bear some weight upon the affected member, but this causes
much distress. In one instance the author observed a transverse fracture
of the lower third of the radius which was not positively diagnosed
until about ten days after injury was inflicted. In this case, without
doubt, the subject originally suffered a sub-periosteal fracture of the
bone and because the animal was a good self nurse, the brachial fascia
supported the radius until the periosteum gave way and the leg dangled.
In this instance infection took place and suppuration resulted. It was
deemed advisable to destroy this animal.
Prognosis.--In adult animals, radial fracture constitutes a grave
condition; generally speaking, prognosis, in such cases, is unfavorable.
Because of the leverage afforded by the extremity, immobilization of the
radius is difficult. Any sort of mechanical appliance, which will
immobilize these parts, is likely to produce pressure-necrosis of the
soft structures so contacted. There is occasioned thereby much pain and
the subject becomes restive, unmanageable and sometimes the splints are
completely deranged because of the animal's struggles, and much
additional injury to the leg is done. Occasionally, an otherwise
favorable case is thus rendered hopelessly impossible to handle, and the
subject must be destroyed several days after treatment has been
instituted.
Consequently, unless all conditions are good, and the affected animal a
favorable subject, young, of good disposition, and the fracture a simple
transverse one, complete recovery is not likely to result from any
practical means of handling.
Treatment.--Mature subjects ought to be put in slings and kept so
restrained throughout the entire time of treatment. Immobilization of
the broken parts of the bone is the object sought. This is attempted by
practitioners who employ various methods, and each method has its
advocates.
Casts are used by some and serve very well in many cases; but because of
their bulk and unyielding and rigid nature, they are not well adapted to
use on fractures of bones proximal to the carpus and tarsus. This is in
reference to plaster-of-paris casts or those of any similar material.
Appliances which depend on glue or other adhesive substances combined
with leather, wood or fiber for their support, are efficacious but not
comfortable.
The use of heavy leather when the member has been suitably padded with
cotton and bandages, constitutes a very good manner of reducing fracture
of the radius or of the tibia. Leather when cut to fit both the medial
and lateral sides of a leg, and firmly held with bandages, will form a
firm support that yields slightly to changes of position, thus making
for comfort of the subject.
Such a splint or support should extend from the fetlock region to the
elbow, but the cotton and bandages are to reach to the foot. When one
considers that, with the supportive appliance placed on each side of the
affected member, rigidity is accomplished as much from tensile strain
put upon the leather as from its own stiffness, it is seen that the
leather need not be of the heaviest--sole leather is unnecessary.
Because of the more comfortable immobilizing appliance, the subject is
less restive, and chances for a successful outcome are materially
increased thereby.
In the mature subject, six or eight weeks' time is required for union of
the parts to occur sufficiently so that splints may be dispensed with.
Rearrangement of the supportive apparatus, however, is possible and
usually necessary during the first few weeks of treatment. By employing
care in handling the parts, the subject will be unlikely to do itself
injury at the time readjustment of splints is being effected.
In foals, it is best to give them the run of a box stall with the
mother. Being agile, they get up and lie at will without doing injury to
the fractured member. The splints (leather is preferable in these cases
also) are looked after and readjusted as necessity demands.
Three or four weeks time is all that is required for the average young
colt to be kept in splints when suffering from simple transverse
fracture of the radius.
Compound fractures are necessarily more difficult to treat than are the
simple variety, but even in such cases recovery results sometimes, and
the practitioner is justified in attempting treatment after having
explained the situation to his client.
Oblique fractures, even when simple, do not completely recover. Muscular
and tendinous contraction, together with the natural tendency for the
beveled contacting parts of the broken bone to pass one another in
oblique fracture, results in shortening of the leg and, if union
results, a large callus usually forms. Where shortening of bones occur,
necessarily, permanent lameness follows.
Wounds of the Anterior Brachial Region.
Etiology and Occurrence.--Contusions and lacerations of the forearm
are of frequent occurrence in horses and are troublesome cases to
handle; particularly is this noticeable where extensive laceration of
the parts occurs. These injuries are caused by animals being kicked; by
striking the forearm against bars in jumping; and in sections of the
country where barbed wire is used to enclose pastures, extensive
lacerated wounds are met with when horses jump into such fences.
Symptomatology.--Any wound which causes inflammation of the structures
of the anterior half of the forearm, is characterized by
swinging-leg-lameness. Depending upon the nature and extent of the
injury, manifestation varies. In cases where laceration has practically
divided all of the substance of the extensor tendons, it is, of course,
impossible for the subject to advance the leg; but where lacerated
wounds involve only a part of the extensor apparatus of the foreleg, not
so much inconvenience is evident, unless the wound is seriously infected
and inflammation involves contiguous structures. Therefore, in many
instances, lameness is more pronounced in contusions of the anterior
brachial region than where tissues have been divided more or less
keenly.
In every instance diagnosis is easily established. The injury is quite
evident, and the manner of locomotion is not in itself an essential
feature to be considered in a discussion of symptoms. Where a contusion
of the anterior brachial structures occurs, there is, in addition to
lameness, swelling which is painful because of the pressure occasioned
by the heavy non-yielding brachial fascia. And where suppuration occurs,
there is then an intensely painful condition which is not relieved until
pus has been evacuated. Rather frequently, drainage for wound secretions
is a difficult problem, and approximation of the divided ends of muscles
is always difficult to maintain.
Treatment.--Contused wounds of the anterior brachial region are
treated along usual lines; that is, attempt is made to stimulate prompt
resolution. Hot or cold applications are employed throughout the acute
stage of the affection. Complete rest is provided for until all pain has
subsided. Later, stimulating liniments are beneficial.
Where no injury is done the periosteum or bone, complete resorption of
all products of inflammation usually occurs, though in many instances,
this is tardy--six weeks or more are sometimes required for recovery to
take place.
If suppuration occurs, it is necessary to provide for drainage as soon
as it is possible to distinguish the presence of pus. Due regard is
given the manner of establishing drainage because of the usual existence
of sub-fascial fistulae. In these cases, one avoids injecting solutions
of aqueous antiseptics. By gently compressing the parts, pus is caused
to drain out and in enforcing a moderate amount of exercise at a walk,
when lameness is not intense, drainage is maintained. Cotton packs,
moistened with hot antiseptic solutions, and kept around the forearm for
several hours daily, are helpful because drainage is facilitated, and
resolution is stimulated by the increase of blood thus attracted to the
parts, and pain materially diminishes.
In lacerated wounds of the anterior brachial region, after having
controlled hemorrhage, an area around the wound margin is freed of hair
by clipping or shaving. The wound is carefully examined, and the best
site for drainage is selected and a suitable opening for wound discharge
is provided for. Where the extensor carpiradialis (metacarpi magnus)
with other structures, is divided and the distal portion is torn
downward, as frequently is the case in barbed wire cuts, it is
necessary to make careful provision for drainage. The wound is
thoroughly cleansed by means of ablutions if necessary; but preferably
by swabbing with pledgets of cotton or gauze which are moistened in
antiseptic solutions. All shreds of macerated tissue are clipped with
scissors and finally the whole wound surface is painted with tincture of
iodin.
If drainage is made by cutting through the tissues in the median portion
of the structures that have been displaced, the opening should be packed
with gauze so that it may remain patent after swelling has occurred.
Such packing is left _in situ_ for twenty-four hours.
The pendant muscular portions of tissues are sutured up by means of
tapes and, while perfect apposition is not ordinarily possible, it is
very essential to train the pendant tissues in their normal position
even if they require resuturing within a week. This minimizes
granulation of tissue, and there results less scar if the detached
portions are kept near, even if not in contact with the proximal wound
margins. The skin together with subcutaneous fascia is sutured on either
side unless drainage is to be provided for on one side, and the
lowermost part of that side is left unsutured.
After-care.--Where extensive suturing of tissues has been necessary,
subjects must be kept quiet. They are best confined in box stalls and
not taken out for several weeks. Particularly is this true where
transverse division of extensors has taken place. Sutures are removed at
the end of from ten days to three weeks as cases permit. Drainage of
wound secretions, which usually become infected, is necessary, because
with obstructed drainage in an infected wound of this kind, there will
result an early destruction of tissue at some point sutured. Daily
irrigation done in a manner that practical asepsis is carried out, is
necessary for about a week. All irrigation is done by way of the
drainage opening, and this with warm aqueous solutions of suitable
antiseptics. After a week or ten days' time, the wound should not be
dressed more frequently than twice weekly.
If it is necessary to leave a portion of the wound uncovered, as in
cases where skin is destroyed, the frequent (three or four daily)
application of a suitable antiseptic powder is necessary to check
exuberant granulation. This may be directly effected by the use of an
astringent or desiccant preparation, and such dressing serves as a
mechanical protection as well.
When such wounds are kept clean, where drainage is properly maintained,
and the subject kept quiet, no particular attention other than the local
application of an astringent lotion (such as the zinc and lead lotion)
is necessary after the first three or four weeks. Usually, if the animal
gnaws at the parts or otherwise manifests evidence of discomfort, it is
an indication that new areas of infection are being established because
of obstructed drainage or retained eschars. A thorough cleansing of the
wound with a two per cent solution of Liquor Cresolis Compositus and
this followed by moistening every part of the wound with tincture of
iodin, will check all such disturbance if done promptly.
Where practically all of the anterior surface of the radius has been
denuded, recovery is tardy and there is in some cases imperfect
extension of the leg for months after the wound has healed. But in such
instances, animals gradually regain complete use of the affected member
and in the course of a year function is fully restored.
Inflammation and Contraction of the Carpal Flexors.
Anatomy.--The structures which are usually considered as true flexors
of the carpus are a group of three muscles, which have separate heads of
origin and different points of tendinous insertion.
The _flexor carpiradialis_ (flexor metacarpi internus) originates from
the medial epicondyle of the humerus. It is inserted to the proximal end
of the medial metacarpal (inner metacarpal or splint) bone. This muscle
is the smaller of the three and is not usually divided in doing carpal
tenotomy.
The _flexor carpiulnaris_ (flexor metacarpi medius) has two heads of
origin; one, the larger, originates from the epicondyle of the humerus
and the other from the posterior surface of the olecranon. The two
heads unite at the upper third of the radius and the muscle, becoming
tendinous, as is the case with the other carpal flexors, is attached by
one point of insertion to the accessory carpal bone (trapezum). The
other blends with the posterior annular ligament of the carpus.
The _ulnaris lateralis_ (flexor metacarpi externus) has its origin from
the lateral epicondyle of the humerus and inserts to the proximal
extremity of the fourth metacarpal (outer splint) bone and by another
attachment to the accessory carpal bone (trapezium) with the tendon of
the flexor carpiulnaris (flexor metacarpi medius).
Acting together, these muscles flex the carpus or extend the elbow and
this action is antagonized by the biceps brachii (flexor brachii) and
extensors of the carpus and phalanges.
Etiology and Occurrence.--Inflammation of the muscular or tendinous
parts of the carpal flexors, does not occur as frequently as does
inflammation of the flexors of the extremity. They are subject to injury
such as is occasioned by hard work and concussion and contract as a
result; but, more frequently a congenital malformation of the leg is
responsible for undue strain upon these parts. Horses that are "knee
sprung" or that have a congenital condition where in the anterior line,
as formed by the radius, carpal and metacarpal bones, is bent forward at
the carpus, are subject to inflammation and contraction of the carpal
flexors. When these flexors are contracted, the condition is commonly
known among horsemen as "buck knee." In itself, inflammation of the
carpal flexors is not a condition which is likely to prove troublesome,
but because of carpal involvement (which is often present) the cause of
the trouble remains, and inflammation of the carpal flexors recurs or
becomes chronic and contraction of tendons results.
Symptomatology.--Inflammation of the carpal flexors, when acute and
uncomplicated, is characterized by a painfully swollen condition of the
affected tendons. No weight is borne upon the affected leg and the
carpal joint is flexed. Mixed lameness is present. There is no
difficulty encountered in arriving at a diagnosis because of the very
noticeably inflamed parts.
Many fully developed cases of contraction of the tendons of the carpal
flexors are observed where the condition has become established
gradually and no lameness has resulted from tendinitis or carpitis. In
some of these cases, subjects are stumblers and when they are carelessly
handled or kept at fast work over irregular or hard roads, chronic
carpitis with hyperplasia of the structures of the anterior carpal
region results, owing to frequent bruising from falls.
[Illustration: Fig. 10--Contraction of carpal flexors, "knee sprung."]
Where inflammation is caused by a puncture wound and subfascial
infection occurs, there is evident manifestation of pain. No weight is
supported by the affected member and because of the pressure, occasioned
by the swollen muscles confined within the non-yielding brachial fascia,
there exists marked supersensitiveness of the affected parts. Flexion of
the elbow is avoided because contraction of the biceps brachii (flexor
brachii) or the extensors, which are antagonists of the flexors of the
carpus, tenses the carpal flexors and pain is thereby increased.
However, in most instances, the practitioner's attention is not directed
to typical and uncomplicated cases, but to subacute or chronic
inflammations which are often attended with contraction of the tendinous
parts of the carpal flexors, and in such cases carpitis is present.
Animals so affected have lost the rigidity which characterizes the
normal carpal joint when the leg is a weight bearing member, and because
of its sprung condition, the leg trembles when supporting weight.
Treatment.--Acute inflammation is treated by means of local
application of cold or hot packs until the pain and acute stage of
inflammation has subsided and later stimulating liniments are indicated.
Absolute quiet must be enforced. Especially where the carpus is involved
must the subject be kept quiet until all evidence of inflammation has
subsided.
The application of vesicants or line-firing is beneficial in subacute
inflammation of the tendons of the carpal flexors. Where contraction of
tendons exists and no osseous or ligamentous change prevents correction
of the condition, tenotomy is necessary. The reader is referred to
Merillat's "Veterinary Surgery"[17] for a good description of the
technic of this operation.
In all serious cases of inflammation of the carpal flexors, whether
tenotomy has been performed or not, the subject needs a long period of
rest subsequent to treatment. In fact, three or four months at pasture
is necessary to permit of recovery and this where no congenital
deformity has predisposed the subject to such affection of the flexors.
Return to work must be gradual and the character of the work such as to
enable the animal to become inured to service without a recurrence of
the trouble if possible.
It follows then, that tenotomy, here as in other cases, is not practical
from an economic viewpoint, unless the animal be of sufficient value to
justify the long period of rest for recovery. Tenotomy is not of
practical benefit unless ample time is allowed for regeneration of
divided tendinous tissue.
Fracture and Luxation of the Carpal Bones.
Etiology and Occurrence.--Fracture of the carpal bones is of
infrequent occurrence in horses and, when it does occur, it is usually
due to injuries, and because of their nature (resulting as they
generally do from heavy falls or in being run over by street cars or
wagons), a comminuted fracture of one or more bones exists. The
accessory carpal bone (trapezium) is said to be fractured at times
without being subjected to blows or like injuries, but this is
exceptional.
Luxations of the carpal joint are of rare occurrence, and very few cases
of this kind are on record. Walters[18] reports a case of
carpometacarpal luxation in a pony wherein reduction was spontaneous and
an uneventful recovery followed. His reason for reporting the case, as
he states, is its rarity.
Symptomatology.--Fractures of the carpal bones as they usually take
place are diagnosed without difficulty. Because of their usually being
comminuted, abnormal movement of the joint is possible. Such movement is
not restricted and flexion of the leg at the carpus in any direction is
possible. Crepitation is readily detected and frequently these fractures
are of the compound-comminuted variety.
In fracture of the accessory carpal bone (trapezium) or in fracture of
any other single bone when such exists, there is no increase in the
movement of the joint. The accessory carpal bone may be readily
manipulated and when fractured, its parts are more or less displaced.
Recognition of fracture of any other single carpal bone must be done by
detecting crepitation unless it be a compound fracture, whereupon
probing is of aid in establishing a diagnosis.
Carpal luxation when present is to be recognized by finding the apposing
carpal bones joined in an abnormal manner--that is, out of position.
There is restricted or suspended function of the joint, and in the cases
recorded, no difficulty has been experienced in making a diagnosis. The
carpometacarpal portion of the articulation is the part which is usually
affected.
Prognosis and Treatment.--There is no chance for complete recovery in
the usual case of carpal fracture because of the fact that there results
sufficient arthritis to destroy articular cartilage beyond repair. In
the average instance, because of arthritis which persists for a
considerable length of time, more or less ankylosis results. At best,
one can only hope for partial recovery, that is to say, the member may
regain its usefulness as a weight-supporting part, but because of
restricted or abolished joint function, locomotion is more or less
difficult. Exostoses, articular and periarticular, occur and the carpus
usually becomes a large immobile articulation. There is danger of
infection resulting in simple carpal fractures and, needless to say, in
a compound-comminuted fracture of the carpus, infection usually occurs
and a fatal outcome is probable.
When treatment is instituted, antiseptic precautions are taken in
handling the compound fractures, and in any case immobilization of the
parts is sought. Here, as has been previously pointed out, it is best to
employ leather splints, so that a maximum degree of rigidity with a
minimum of distress and inconvenience to the patient will result. The
leg must be bandaged from the hoof upward, making use of a sufficient
amount of cotton to ensure against pressure-necrosis. The leather
splints are placed mesially and laterally and, of course, need to extend
as high as the proximal end of the radius. Subjects must be kept in
slings until union of bones has become established, and as a rule there
will then exist marked ankylosis.