LAMENESS IN THE HIND LEG.
Anatomo-Physiological Consideration of the Pelvic Limbs.
The pelvic bones as a whole constitute the analogue of the scapulae with
respect to their function as a part of the mechanism of locomotive and
supportive apparatus of the horse. The manner of attachment or
connection between the ilia and the trunk is materially different from
that of the scapulae, however, and the angles as formed by the long axes
of the ilia in relation to the spinal column are maintained by two
functionally antagonistic structures--the sacrosciatic ligaments, and
the abdominal muscles by means of the prepubian tendon. The sacro-iliac
articulations are such that a very limited amount of movement is
possible; free movement, however, is unnecessary because of the
enarthrodial (ball and socket) femeropelvic joint.
The various muscles which exert their effect upon the pelvis in changing
their relationship between the long axes of the ilia and spinal column,
are concerned but little more in propulsion and weight bearing than are
the pectoral muscles. A general treatise on the subject of lameness does
not properly include such structures any more than it does the various
affections of the dorsal, lumbar and sacral vertebrae or inflammation of
the abdominal parietes. Involvement of such parts cause manifestations
of lameness but the matter of establishing a diagnosis is difficult in
many instances and in some cases impossible.
The femeropelvic articulation is formed by the hemispherical head of the
femur and the acetabulum; the latter constituting a cotyloid cavity
which is deepened by the cotyloid ligament.
The round ligament (ligamentum teres) is the principal binding structure
of the hip joint and it arises in a notch in the head of the femur and
is attached in the subpubic groove close to the acetabular notch.
Another ligament, peculiar to Equidae--the accessory (pubiofemoral)--is
attached to the head of the femur near the round ligament and passes
through the cotyloid notch and along the under side of the pubis. It
is inserted or blends with the prepubic tendon. This ligament prevents
extreme abduction of the leg. The joint capsule encompasses the
articulation and is attached to the brim of the acetabulum and the edge
of the head of the femur.
[Illustration: Fig. 40--Sagital section of right hock. The section
passes through the middle of the groove of the trochlea of the tibial
tarsal bone. 1 and 2. Proximal ends of cavity of hock joint. 3. Thick
part of joint capsule over which deep flexor tendon plays. 4. Fibular
tarsal bone (sustentaculum). A large vein crosses the upper part of the
joint capsule (in front of 1). (From Sisson's "Anatomy of the Domestic
Animals.")]
[Illustration: Fig. 41--Muscles of right leg; front view. The greater
part of the long extensor has been removed. 1, 2, 3. Stumps of patellar
ligaments. 4. Tuberosity of tibia. (From Sisson's "Anatomy of the
Domestic Animals.")]
The stifle joint is analagous to the knee joint of man and is to be
considered an atypical ginglymus (hinge) articulation formed by the
femur, tibia and patella. The ligaments are femerotibial, femeropatellar
and capsular.
In addition to the usual provision for articulation of bones there are
situated cartilaginous _menisci_ between the condyles of the femur and
the head of the tibia. These discs surround the tibial spine and are
otherwise shaped to fit perfectly between the articular portions of the
femur and tibia.
Collateral ligaments (internal and external lateral) pass from the
distal end of the femur to the proximal portion of the tibia. The mesial
(internal) arises from the internal condyle of the femur and is attached
to a rough area below the margin of the medial (internal) condyle of the
tibia. The lateral (external), shorter and thicker, arises from the
depression on the lateral epicondyle and inserts to the head of the
fibula.
The crucial or interosseus, anterior and posterior, are situated between
the femur and tibia, and according to Smith,[34] the crucial ligaments
are necessary to properly join the two bones, because of the character
of the structure of the articular ends of the femur and tibia.
The femeropatella ligaments are two thin bands which reinforce the
capsular ligament. They arise from the lateral aspects of the femur,
just above the condyles and are inserted to the corresponding surfaces
of the patella.
The patellar ligaments are three strong bands which arise from the
antero-inferior surface of the patella, and are inserted to the anterior
aspect of the tuberosity of the tibia.
Taken as a whole, the tarsal bones, interarticulating and articulating
with the tibia and metatarsal bones form the hock joint and this
articulation is analagous to the carpus. As with the carpus, there is
less movement in the inferior portion of the joint than in the
superior part of the articulation. The chief articulating parts are the
tibia with the tibial tarsal bone (astragulus).
[Illustration: Fig. 42--Muscles of lower part of thigh, leg and foot;
lateral view, o', Fascia lata; q, q', q", biceps femoris; r,
semitendinosus; 21', lateral condyle of tibia. The extensor brevis is
visible in the angle between the long and lateral extensor tendons.
(After Ellenberger-Baum, Anat. für Künstler.) (From Sisson's "Anatomy of
the Domestic Animals.")]
The capsular ligament is attached around the margin of the articular
surfaces of the tibia, to the tarsal bones, the collateral ligaments
(internal and external lateral) and to the metatarsus.
[Illustration: Fig. 43--Right stifle joint; lateral view. The
femoro-patellar capsule was filled with plaster-of-Paris and then
removed after the cast was set. The femoro-tibial capsule and most of
the lateral patellar ligament are removed. M. Lateral meniscus. (From
Sisson's "Anatomy of the Domestic Animals.")]
The common ligaments of the tarsal joint are the collateral, the plantar
(calcaneo-metatarsal and c. cuboid) and dorsal ligaments (oblique).
The medial (internal lateral) ligament serves to join the medial
(internal) tibial malleolus with tibial tarsal (astragalus) and other
tarsal bones.
The lateral (external lateral) ligament is inserted to the lateral
(external) tibial malleolus and its distal portions are attached to the
tibial tarsal (astragalus), fibular tarsal (calcaneum) bone, fourth
tarsal (cuboid) and metatarsus bones.
[Illustration: Fig. 44--Left stifle joint; medial view. The capsules are
removed. (From Sisson's "Anatomy of the Domestic Animals.")]
The plantar ligament (calcaneo-cuboid) is a strong flat band which is
attached to the plantar surface of the fibular and fourth tarsal bones
(calcaneum and cuboid) and the head of the lateral metatarsal (external
small) bone.
The dorsal (oblique) ligament is attached above to the distal tuberosity
on the inner side of the tibia. It is inserted below to the central
(cuneiform magnum) and third (c. medium) tarsal bones, to the proximal
ends of the large and outer small metatarsal bones.
The tarsus is a true hinge joint and because of the great strain which
it sustains, is subject to frequent injury. About seventy-five percent
of cases of lameness affecting the hind leg may be said to arise from
disease of the hock.
As members of locomotion the legs receive strains of two kinds: those of
concussion and weight-bearing and strains of propulsion; the latter are
the greater. In the horse as a work animal, the hind legs are probably
subjected to greater strains than are the front but the manner of
construction of the various parts of the pelvic limbs with the possible
exception (according to some authorities) of the tibial tarsal joint,
offsets this condition.
The femur may be considered analagous to the humerus in that it bears a
similar relationship to the ilium, that exist between the humerus and
scapula. Further flexion during repose is prevented chiefly by the
glutens medius (maximus) muscle and its tendons. The larger tendon
inserts to the summit of the trochanter major of the femur and
corresponds to the biceps brachii in the action of the latter on the
scapulohumeral joint, except that the gluteus medius, in attaching to
the femoral trochanter, exerts its effect as a lever of the first class.
Because of the relationship between the long axes of the femur and iliac
shaft it is evident that the angle formed by these two bones is
maintained chiefly by the gluteus muscles during weight bearing.
Contraction of muscular fibers of the gluteus medius causes extension of
the femur and muscular strain is prevented to a great degree by the
inelastic portion of this muscle. The chief physiological antagonistics
of the glutei are the quadriceps femoris and tensor fascia lata.
While the leg is supporting weight the stifle joint is fixed in position
mainly by the quadriceps femoris group of muscles which are attached to
the patella. Tendinous fibres intersect this muscular mass and relieve
muscular strain during weight bearing. Because of the manner in which
the patella functionates with the trochlea of the femur, comparatively
little energy is required to prevent further flexion of the stifle
joint. The patella, according to Strangeways, may be considered a
sesamoid bone.
[Illustration: Fig. 45--Left stifle joint; front view. The capsules are
removed. 1. Middle patellar ligament. 2. Stump of fascia lata. 3. Stump
of common tendon of extensor longus and peroneus tertius. (From Sisson's
"Anatomy of Domestic Animals.")]
The quadriceps group of muscles is assisted by the anterior digital
extensor (extensor pedis) peroneus tertius and tibialis anticus (flexor
metatarsi) muscles. The latter pair (flexor metatarsi, muscular and
tendinous portions, because of their attachment to the external condyle
of the femur and to the metatarsal bone) are enabled to automatically
flex the tarsal joint when the stifle is flexed.
The hock is kept fixed in position by the gastrocnemius and the
superficial digital flexor (perforatus). The latter structure, which is
chiefly tendinous, originates in the supracondyloid fossa of the femur
and has an insertion to the summit of the fibular tarsal (calcis) bone.
It relieves the gastrocnemius of muscular strain during weight bearing.
Smith[35] styles the function of the stifle and hock joints a
reciprocating action, and we quote from this authority the following:
From what has been said, it is evident that flexion and extension
of stifle and hock are identical in their action. When the stifle
is extended, the hock is automatically extended, nor can it under
any circumstances flex without the previous flexion of the stifle.
There is no parallel to this in the body. The two joints, though
far apart, act as one, and they are locked by the drawing up of the
patella, and in no other way. The so-called dislocation of the
stifle in the horse is a misnomer. That the patella is capable of
being dislocated is beyond doubt, but the ordinary condition
described under that term, when the stifle and hock are rigid while
the foot is turned back with its wall on the ground, is nothing
more than spasm of the muscles which keeps the patella drawn up.
The moment they relax the previously immovable limb and useless
foot have their function restored as if by magic, but are
immediately thrown out of gear in the course of a few minutes as a
recurrence of the tetanus of the petallar muscle takes place. The
fascia of the thigh, like that of the arm, is a most potent factor
in giving assistance to the constant strain imposed on the muscles
of the limbs during standing.
Below the hock the hind limb is arranged like that of the fore, the
deep flexor (perforans) receiving its additional support from the
"check ligament," as in the fore leg.
The natural attitude of standing adopted by the horse is to rest on
three legs--one hind and two fore. If he is alert, he stands on all
four limbs; but if standing in the ordinary manner, he always rests
on one hind leg. He does not remain long in this position without
changing to the other. Hour by hour he stands, shifting his weight
at intervals from one to the other hind leg, and resting its fellow
by flexing the hock and standing on the toe. He never spares his
fore-limbs in this manner in a state of health, but always stands
squarely on them.
Hip Lameness.
Fortunately, because of the heavy musculature which goes to form a part
of the locomotive apparatus of the rear extremity, hip lameness is
comparatively rare. While the term is in itself ambiguous and signifies
nothing more definite than does "shoulder lameness," yet diagnosis of
almost any condition that may be classed under the head of "hip
lameness" is not easy except in cases where the cause is obvious, as in
wounds of the musculature and certain fractures. To the complexity which
the gait of the quadruped contributes, because of its being four-legged,
there is added the complicated manner of articulation of the bones of
the hind leg. This involves the hip in the manner of diagnostic problems
and because of the inaccessibility of certain parts, owing to the bulk
of the musculature of these parts, diagnosis of some hip ailments
becomes an intricate problem. Consequently, in some instances, before
one may arrive at definite and enlightening conclusions, repeated
examinations are necessary as well as a knowledge of reliable history
and recorded observations of the subject over a considerable period.
Rheumatic affections, when present, usually cause recurrent attacks of
lameness; myalgia, due to subsurface injury occasioned by contusion,
generally produces an ephemeral disturbance; and while these are
examples of cases where occult causes are active, they are by no means
unprecedented. In cases where the cause of lameness is not definitely
located, and when by the process of exclusion one is enabled to decide
that the seat of trouble is in the hip, a tentative diagnosis of hip
lameness is always appropriate.
In one instance a Shetland pony evinced a peculiar form of intermittent
lameness which affected the left hip, and repeated examinations did not
disclose the cause of the trouble. After about a year there was
established spontaneously an opening through the integument overlying
the region of the attachment of the psoas major (magnus), through which
pus discharged. With the occurrence of this fistula, lameness almost
entirely disappeared, but the emission of a small amount of pus
persisted for more than a year. The subject was not observed thereafter
and the outcome in this case is not a matter of record. Whether there
existed a psoic phlegmon due to metastatic infection or necrosis of a
part of a lumber or dorsal vertebra is a matter for speculation. Thus
the presence of some anomalous conditions which affect the pelvic region
and cause lameness may be discovered, yet both in hip and shoulder
regions causes may not be definitely located by means of practical
methods of examination.
Injuries of all kinds are the more frequent causes of hip lameness. In
such cases, lameness may result directly and resolution be prompt, or
the claudication become aggravated in time, due to muscular atrophy or
degenerative changes affecting the hip joint or nerves. Rheumatism or
metastatic infection may be the cause of hip lameness as well as
affections of the pelvic bones, lumbar and sacral vertebrae. Hip
lameness may also be provoked by melanotic or other tumors.
In the diagnosis of hip lameness, one is guided in a general way by the
character of the impediment manifested. Swinging-leg lameness is often
present and the impediment is more accentuated when the animal is caused
to step backward. In many cases lameness is mixed, being about equally
noticeable during weight bearing and while the member is being swung. By
exclusion of causes which might affect other parts; one may definitely
locate the cause of the trouble or determine that a certain region is
affected.
The sudden manifestation of lameness is indicative of injury; thermic
disturbances may signalize metastatic infection; history, if dependable,
is always helpful. Repeated observations, taking into account the course
which the affection assumes during a period of a few days, often serve
to afford a means of establishing a diagnosis in baffling cases.
Fractures of the Pelvic Bones.
The os innominatum may be so fractured that the pelvic girdle is broken,
as in fracture of the iliac shaft, or in a manner that the girdling
continuity of the innominate bones is not interrupted. It naturally
follows that greater injury is done when the pelvic girdle is broken
than when it is not, except in cases where the acetabulum is involved
and its brim not completely divided.
Etiology and Occurrence.--Pelvic fractures are usually caused by falls
or other manner of contusion. Cases are reported where it would seem
that fracture of the iliac angle resulted from muscular contraction, but
it is certain that most fractures of this kind are due to collisions
with door jambs or similar injuries. In old horses especially, fracture
of pelvic bones occurs frequently. This form of injury is of more
frequent occurrence in animals of all ages that work on paved streets.
The country horse is not subjected to the uncertain footing of the
slippery pavement, nor to injuries which compare with those caused by
contusions sustained in falling upon asphalt or cobble-stones.
Symptomatology.--While in many cases of pelvic fracture lameness or
abnormal decumbency are the salient manifestations, yet the pathognomic
symptoms are crepitation or palpable evidence which may be obtained by
rectal or vaginal examination. In fractures of the angle of the ilium
and the ischial tuberosity, perceptible evidence always exists.
In cases where fracture of some portion of the pelvic girdle is
suspected and the subject is able to walk, crepitation is sought by
placing one hand on an external angle of the ilium and the other on the
ischial tuberosity and the animal is then made to walk. Or, by placing
the hands as just directed, an assistant may grasp the horse's tail and
by alternately exerting traction on the tail and pushing against the hip
in such manner that weight is shifted from one leg to the other,
crepitation may be detected.
Fracture of the pubis near its symphysis constitutes a grave injury, as
there is danger of the bladder becoming caught in the fissure and
perforation of its wall may result. Such a case is reported by
Bauman[36] wherein a three-year-old gelding bore the history of having
been lame for ten days. Upon rectal examination the bladder was found to
be hard and tumor-like and about the size of a baseball. The body of the
ischium in this case was fractured and a rent in the bladder was caused
by a sharp projecting piece of bone. Autopsy revealed, in addition to
the fracture and rent of the bladder wall, a large quantity of urine in
the peritoneal cavity.
In other instances hemorrhage caused death and not infrequently
infection was responsible for a fatal issue. Moller,[37] quoting Nocard,
describes a case where fracture occurred through the region of the
foramen ovale and paralysis of the obturator nerve followed.
Fractures which include the acetabular bones cause great pain. This is
manifested by marked lameness, both during weight bearing and when the
member is swung. Such cases terminate unfavorably--complete recovery is
impossible.
Where small portions of the angle of the ilium are broken, and the skin
is left intact, there exists the least troublesome class of pelvic
fracture. If large portions of the ilium are fractured, considerable
disturbance results. There eventually occurs more or less displacement
in such cases, if such displacement does not take place at the time of
injury. The same may be said of fracture of the tuber ischii, but when
these bones are fractured a more serious condition results.
Treatment.--When a case is found to be uncomplicated, that is, if the
fracture is such that recovery seems possible and after having
determined that treatment may be practicable, the first consideration is
that of confining the subject in suitable slings. In many cases of
pelvic fracture, the affected animal will need to be kept in slings from
six weeks to three months, and it becomes a difficult problem to
minimize the distress during this long period of confinement in the
peculiar manner required for favorable outcome.
The pattern of sling employed should be the best that is obtainable and
the matter of its adjustment is quite important lest unnecessary chafing
or even necrosis of skin result. Frequent readjustment may be necessary,
and time is well spent in this manner since this contributes materially
toward a favorable termination by encouraging the subject to remain
quiet so that coaptation of the broken bones may be maintained. Aside
from slings, mechanical appliances that are helpful in the treatment of
these cases are not yet in use.
A regimen that is nutritive and at the same time laxative is essential
and in some cases cathartics and enemata are necessary. Also, during the
first few days, if there is retention of urine, catheterization is
imperative. In a word, the handling of such cases consists largely in
keeping the subject inactive, as comfortable as possible, and giving
attention to suitable diet.
Simple fracture of the external iliac angle needs no particular
attention, except that the subject is kept quiet until lameness
subsides. In all cases where much of the bone is broken, the animal is
blemished, but interference with function does not follow. If infection
results because of a compound fracture, loose pieces of bone must be
removed surgically and drainage provided for.
In fracture of the ischial tuberosity, infection is more apt to result
than in like injury of the ilium, and greater displacement of bone
occurs. This displacement, due to contraction of the attached muscles,
is in some instances a contributing cause to the infection which often
follows in these cases. In females where the body of the ischium is
fractured, lacerations of the vagina may be present, and this
constitutes a serious complication which usually terminates fatally.
After-care in fracture of the pelvic girdle consists principally in
allowing a protracted period of rest before subjects are put to work.
Fractures of the Femur.
Etiology and Occurrence.--This is a comparatively rare injury in the
horse because of the protection afforded the femur by the heavy
musculature. Fragilitas of the bone probably exists in many cases when
fracture of its diaphysis occurs. It is generally conceded that the neck
of the femur is rarely broken because of a lack of constriction in this
part, but fracture of the trochanters has been recorded rather
frequently. However, Lienaux and Zwanenpoete[38] state that fracture of
the neck of the femur is of frequent occurrence in Belgian colts.
Tapley[39] reports in the Veterinary Journal (English) fracture of the
head and internal trochanter of the femur and patellar luxation
occurring simultaneously affecting a mule. In this case the mule was
found decumbent on a concrete floor. After three weeks, the subject was
destroyed and autopsy revealed rupture of the left pubiofemoral
ligament, tearing with it a portion of the articular surface of the
femur. The internal trochanter was also fractured in four small pieces.
In this case it is fair to suppose that the mule in trying to regain
footing on a slippery floor violently abducted the legs and fracture
resulted. It is possible also that a temporary luxation of the patella
took place first and caused the animal to struggle in such manner that
fracture followed.
[Illustration: Fig. 46--Oblique fracture of the femur of a 1,500
six-year-old draft horse. Showing shortening of bone, owing to a lateral
approximation of the diaphysis because of muscular contraction. Photo by
Dr. Edward Merillat.]
Symptomatology.--According to Cadiot and Almy,[40] "regardless of the
location of femoral fractures, the subject is usually intensely lame,
the animal frequently walking on three legs--fractures of the diaphysis
are characterized by an abnormal mobility."
As a rule, crepitation is to be recognized in fractures of the shaft of
the bone, by passively moving the leg to and from the medial plane
(adduction and abduction).
Fracture of the trochanter major is signalized by local swelling and
evidence of pain; the forward stride is shortened because this movement
tenses the tendon of the gluteus major (maximus) which is attached
principally to the trochanter.
[Illustration: Fig. 47--Same bone as in Fig. 46 after about six months'
treatment. In this case Dr. Merillat employed a weight to counteract
muscular contraction. It is noticeable that very little provisional
callus has formed in this case, and in spite of unusual ingenuity and
good facilities for caring for the subject, union of bone did not
occur.]
Treatment.--Reduction of femoral fracture in the horse is practically
impossible, and retaining the broken bones in coaptation is not possible
by means of mechanical appliances. Consequently, prognosis is
unfavorable in fracture of the body of the femur. When union of bone
occurs, there results shortening of the leg and animals are rendered
permanently lame. If the immediate region of the head of the bone is
involved as well as in case of fracture of the condyles, an incurable
arthritis ensues.
Where the trochanters are broken, chronic lameness and muscular atrophy
is the result. Therefore, it is evident that, because of the manner of
function of the femur, the leverage afforded by its great trochanter and
its heavy muscular attachments, fractures of this bone in the horse do
not terminate favorably.
Luxation of the Femur.
Etiology and Occurrence.--Uncomplicated femoral luxation is of less
frequent occurrence in the horse than in the other domestic animals.
The deep cotyloid cavity renders disarticulation difficult and luxation
does not often take place. Complications that usually occur are rupture
of the round (coxofemoral) ligament or fracture of the neck of the
femur. Falls or violent strains are necessary to produce this luxation.
Goubaux is quoted by Cadiot and Almy[41] as having observed the head of
the femur in an instance wherein luxation had long existed. In this case
autopsy revealed the fact that the inner portion (two-thirds) of the
head of the femur had completely disappeared.
Luxation of the femur is observed in old emaciated animals that are
worked on slippery pavements. Occasionally, evidence of chronic luxation
of the femur is observed in the anatomical laboratory. The chronicity of
the condition is obvious when one notes the well formed articulation
which Nature provides for the head of the femur, where fracture or other
serious complications are not present.
Symptomatology.--In every case there must exist either restriction of
movement or an evident abnormal position of the leg, or both conditions
may exist at once. Also, the leg may be markedly shortened.
Manifestation of this affection varies, depending upon the character of
the luxation (position of the head of the humerus with relation to the
acetabulum). Lusk[42] cites a case of a mule which had suffered femoral
luxation. The animal was destroyed and on autopsy the head of the femur
found to be contained within a false articular cavity situated about
four inches above the acetabulum. In Dr. Lusk's case as he states it,
the following symptoms were presented: "Limb shortened and fixed in a
position of adduction. While standing the affected limb hung directly
across and in front of the opposite one; upper trochanter very
prominent; skin over hip joint very tense. The mobility of the limb was
very limited, especially in the forward direction."
Being very prominent when there is an upward luxation and less
perceptible in downward displacement, the location of the trochanter
major is an indicator of the character of the luxation with respect to
the position of the head of the femur. This variation of position
causes abnormal tenseness or looseness of the skin over the region of
the trochanter major. Rectal examination is of aid in locating the head
of the humerus.
Treatment.--When it is evident that a subject should be given
treatment and not destroyed, the animal must be cast and completely
anesthetized. With complete relaxation thus secured by rotation of the
limb, using the hip joint region as a pivot, reduction may be effected.
Traction is exerted in the same direction from the acetabulum that the
head of the femur is situated and by pressing over the joint, the
displaced bone may be returned in position. If luxation is downward,
traction on the extremity will tend to dislodge the head of the femur
from the inferior acetabular margin making reduction possible.
The same general plan which is ordinarily employed in correcting
luxation is indicated here, but because of the heavy musculature of the
hip, complete anesthesia is imperative in all such manipulations.
Gluteal Tendo-Synovitis.
The glutens medius (g. maximus) muscle is inserted chiefly by means of
two tendons; one to the summit of the trochanter major of the femur and
the other passing over the anterior part of the convexity of the
trochanter, and being attached to the crest below it. The trochanter is
covered with cartilage, and a bursa (the trochanteric) is interposed
between the tendon and the cartilage.
Etiology and Occurrence.--This affection is probably caused in most
instances by direct injury to the parts, such as may be occasioned by
being kicked, falling on pavement, or being struck by the body of a
heavy wagon. Strains in pulling or in slipping are undoubtedly causative
factors and in draft horses such strains may result in involvement of
this synovial apparatus.
Symptomatology.--If pain be severe and inflammation acute, weight may
not be borne with the affected member. There is some local manifestation
of the condition in acute cases. Swelling of the tissues contiguous to
the bursa is present and pain is evinced upon manipulation of the
parts. A characteristic gait marks inflammation of the trochanteric
bursa, and as Gunther has put it, the subject generally moves or trots
as does the dog--the sound member being carried in advance of the
affected one and the forward stride of the diseased leg is shortened. In
some chronic cases crepitation is discernible by holding the hand on the
trochanter while the subject walks.
Treatment.--In the first stages of an acute affection absolute quiet
must be enforced; local antiphlogistic applications are beneficial.
Later, vesication of a liberal area surrounding the trochanter major is
indicated. Where the condition has become chronic in horses that are to
be kept at heavy draft work there is little chance for complete
recovery. And, naturally, one is not to expect resolution in cases where
there exist erosion and ossification of cartilage--where crepitation is
discernible.
Paralysis of the Hind Leg.
Aside from paraplegic conditions due to disease of the cord or the
lumbosacral plexus, and monoplegic affections resultant from
disturbances of this plexus, paralysis of certain nerves are
occasionally encountered.
Anatomy.--The lumbosacral plexus results substantially from the union
of the ventral branches of the last three lumbar and the first two
sacral nerves, but it derives a small root from the third lumbar nerve
also. The anterior part of the plexus lies in front of the internal
iliac artery, between the lumbar transverse processes and the psoas
minor. It supplies branches to the iliopsoas[43] (designated by Girard,
the iliacomuscular nerves). The posterior part lies partly upon and
partly in the texture of the sacrosciatic ligament. From the plexus are
derived the nerves of the pelvic limb (Sisson).
Paralysis of the Femoral (Crural) Nerve.
Anatomy.--The femoral nerve (crural) is derived chiefly from the
fourth and fifth lumbar nerves. It runs ventrally and backward, at
first between the psoas major and minor, then crosses the deep face of
the tendon of the latter and descends under cover of the sartorious over
the terminal part of the iliopsoas. It innervates the psoas major
(magnus), psoas minor (parvus), sartorious, rectus femoris, vastus
lateralis (interims). Branches supply the stifle and the adductor and
pectineus muscles.
Etiology and Occurrence.--While paralysis of the femoral nerve, also
known as "dropped stifle" occurs as a result of local injuries and
melanotic tumors in gray horses, most cases are due to azoturia.
So-called crural paralysis or "hip swinney" is occasionally observed but
this is not a condition wherein the nerve is affected in the manner that
characterizes the marked atrophy of quadriceps femoris (crural) muscles
in some cases of hemaglobinuria. This form of paralysis according to
Hutyra and Marek is due primarily to diffuse degeneration of the
muscles.
Symptomatology.--When muscular atrophy is not extensive no particular
evidence of this condition may be manifested while the subject is at
rest, but where muscular waste has occurred, the nature of the ailment
is at once recognized. Since the femoral nerve supplies the quadriceps
femoris muscles, it follows that when the psoic portion of this nerve
becomes diseased, the stifle loses its support, and in a unilateral
involvement when the subject attempts to walk on the affected member,
the stifle sinks down for want of support and the leg collapses unless
weight is caught up with the other leg. Often, following azoturia, a
bilateral affection is to be observed.
Treatment.--Horses may be restrained in the standing position, and in
the average instance, a twitch and hood are all the restraining
appliances necessary.
In cases where the disease is unilateral and atrophy is not of too long
standing, recovery is possible in vigorous subjects. All affections,
however, wherein degenerative changes involve the nerve trunk, whether
due to diffuse myositis or pressure from malignant tumors, will not
yield to treatment.
The same general plan of treatment is indicated that is described on
page 74 in the consideration of atrophy of the scapular muscles. It is
especially important to provide for the subject to be exercised when
there is atrophy of the quadriceps muscles following azoturia.
In addition to the foregoing, good results have attended the use of
intramuscular injections of oxygen. The technic of the operation
consists in preparing the area of skin which covers the atrophied
muscles as for any operation. The hair is clipped over five or six or
more circular areas of about an inch in diameter; the skin is cleansed
and then painted with tincture of iodin.
A long heavy sterile needle, which is connected with an oxygen tank by
means of six feet of rubber tubing, is thrust into the depths of the
affected muscles and the gas is gently introduced into the tissues. One
needs exercise extreme care that the gas enter slowly because great pain
is produced by the sudden injection of the oxygen. Likewise too much of
the gas must not be introduced at one place. When the oxygen is slowly
introduced it may be allowed to enter the tissues until the subject
gives evidence of experiencing considerable pain, or if the parts are
not particularly sensitive, a reasonable amount (enough to cause a mild
degree of diffuse inflammation) is introduced at each one of five or six
points. In large animals more points of injection may be used.
No infection or other bad results will follow the execution of a good
technic and the treatment may be repeated every three or four weeks
until either marked regeneration of tissue is evident or the case is
obviously proved hopeless.
Paralysis of the Obturator Nerve.
Anatomy.--The obturator nerve, situated at first under the peritoneum,
accompanies the obturator artery through the obturator foramen and
gaining the muscles on the internal face of the thigh, terminates in the
obturator externus, adductors, pectineus and gracilis, also giving twigs
to the obturator internus (Strangeways).
Etiology and Occurrence.--This condition occurs upon rare occasions as
the result of injury such as falls which cause extreme abduction of the
legs, or in pelvic fracture where the nerve is directly injured, or
when melanotic tumors or other new growths compress the nerve in such
manner that its function is suspended. Paralysis of the obturator nerve
or nerves is met with rather frequently, notwithstanding, in mares,
following dystocia. The nerves (one or both) may become bruised at the
brim of the obturator foramen by being caught between the pelvis and the
body of the fetus in some cases of protracted labor.
Symptomatology.--In a unilateral affection there may be little
evidence of the trouble while the subject is standing; or there is to be
seen some abduction; or the affected member may present abduction of the
stifle and stand "toe outward." If the animal is walked there will be
manifested more or less abduction and the character of the impediment
varies according to the nature of the involvement.
Following protracted cases of labor in some instances where only a
unilateral paralysis exists, walking is performed with difficulty; the
subject may be unable to support weight with the affected member and is
obliged to hop on the one sound hind leg. In bilateral affections, they
are unable to rise. If the condition is severe the sling is required to
keep the subject standing, and with this care, recovery will follow.
Treatment.--If new growths or callosities or similar conditions affect
the nerve, little, if any, hope for recovery exists. In young and
vigorous subjects where cause is not definitely known, a course of
strychnin may be given. Good nursing, providing for the subject's
comfort and allowing moderate exercise, constitute rational treatment.
Stimulating embrocations on the abductor muscles resorted to in cases
during the incipient stage may prove helpful.
When paralysis of the obturator nerve occurs as a post-partum
complication, and other conditions are favorable, the subject should be
raised to its feet without unnecessary delay. If the mare is unable to
assist in regaining her feet, a sling is required. Usually little else
is necessary and after a few days in the sling the subject can get about
unassisted. In the meanwhile the well-being of the affected animal is to
be considered just as in any other case where the patient is so
confined. The foal in such instances constitutes a source of some
trouble, but the average mare offers no serious resistance to the
confinement occasioned by the sling.
Good hygienic care, a suitable diet and full physiological doses of
strychnin are indicated. Cadiot and Almy recommend vaginal douches of
cold water and counterirritation of the region of the inner thigh in
these cases.
Paralysis of the Sciatic Nerve.
Anatomy.--The great sciatic nerve leaves the pelvis in company with
the gluteal nerves, through the great sciatic foramen (notch), passing
downward along the posterior face of the femur. Near the stifle it
passes between the two heads of the gastrocnemius muscle and continues
as the tibial. Branches supply the following muscles--obturator,
semimembranosus (adductor magnus), biceps femoris (triceps abductor
femoris), semitendinosus (biceps rotator tibialis), lateral extensor
(peroneus) and the tibial nerve, its continuation, innervates the
digital flexors.
Etiology and Occurrence.--Paralysis of the great sciatic nerve may be
caused by central disorders, injury in falling, fractures and new
growths. Because of its protected position, this nerve does not often
suffer injury, and paralysis of the sciatic nerve is recorded in a few
instances owing to its rarity.
Symptomatology.--When consideration is given the number of muscles
that are supplied by the sciatic nerve and the function of these
muscular structures, it is obvious that the leg cannot be used in
sciatic paralysis. However, the limb is capable of sustaining weight
when it is fixed in position, but this is done without exertion of
muscular fibers which are supplied by the great sciatic nerve. Trotting
is impossible and flexion of the affected member is also likewise
precluded. The foot is dragged when the subject is caused to advance.
Under the heading "sciatica," Scott[44] has described a case of acute
sciatic affection wherein a pacing horse manifested evidence of great
pain of a nervous character. There were muscular twitchings and the leg
was held off the floor and moved about convulsively. Breathing was very
much accelerated, pulse 85 per minute, the temperature was 103° and
manipulation of the hips augmented the pain.
This was not a paralytic condition and recovery resulted, yet
undoubtedly this was a case which, if not properly cared for, might have
terminated unfavorably.
Treatment.--Prognosis is decidedly unfavorable in paralysis of the
great sciatic nerve. If treatment is attempted, it is to be conducted
along the same general lines as in femoral paralysis. Particular
attention should be given to conditions which will make for the
patient's comfort, and as soon as it is evident that the affection is
not progressing favorably, the subject should be humanely destroyed.
Iliac Thrombosis.
This condition is undoubtedly of more frequent occurrence than we are
wont to grant when one considers the comparatively small number of cases
that are actually recognized in practice. It does not follow, however,
that iliac thrombosis rarely exists. Probably in the majority of
instances there is insufficient obstruction of the lumina of vessels to
provoke noticeable inconvenience. Or, if circulation is hampered to the
extent that function is impaired and manifestations are observed by the
driver, the subject may be permitted to rest a few days and partial
resolution occurs, so that further trouble is not noticeable.
As judged by lesions of the aorta and iliac arteries in dissecting
subjects, the conclusion that arteritis and resultant disorders are of
rather frequent occurrence, is logical.
Etiology.--Inflammation of the vessel walls and resultant
prolifieration of tissue together with the accumulation of clotted blood
becoming organized, serve to obstruct the lumen of the affected artery.
The cause of arteritis is unknown in many instances, but parasitic
invasion and contiguous involvement of vessels in some inflammatory
injuries are etiological factors.
Symptomatology.--A characteristic type of lameness signalizes iliac
thrombosis and the following brief abstract from a contribution on this
subject by Drs. Merillat[45], clearly portrays the chief symptoms:
[Illustration: Fig. 48--Exposure of aorta and its branches, showing
location of thrombi in numerous places. In this case (same as Fig. 49)
Dr. L.A. and Dr. Edward Merillat found the cause of the condition to be
due to sclerastomiasis.]
The seizures are accompanied with profuse sudation, tremors,
dilated nostrils, accelerated respirations and other symptoms of
pain and distress, all of which, together with the lameness,
disappear as rapidly as they had developed, leaving the animal in
an apparently perfect state of health, ready to fall with another
attack of precisely the same kind, as soon as enough exercise is
forced upon it. The rectal explorations may reveal a pulseless
state of one or more of the iliac arteries and a hardness and
enlargement of the aortic quadrifurcation, but sometimes this
palpation fails to disclose any _perceptible_ diminution of the
blood current of these vessels. The obturation being incomplete, it
may be impossible by palpation to decide that thrombosis really
exists. In this event and, in fact, in all eases, the clinical
symptoms are sufficiently characteristic to make a diagnosis
without reservation. It cannot be mistaken for any other disease,
once properly investigated. Any given seizure may easily be
mistaken for azoturia, at first, but a better examination soon
excludes that disease.
[Illustration: Fig. 49--Illustrative of thrombosis of the aorta, iliacs
and branches. Photo by Dr. L.A. Merillat.]
Prognosis and Treatment.--In the majority of instances, when
there is occasioned serious inconvenience, the outcome is not
likely to be favorable, according to Möller. Detachment of a
portion of the thrombus, according to Hoare, may result in the
lodgment of an embolus in the brain or kidneys. The latter
authority also states that muscular atrophy may occur owing to lack
of blood supply in some of these cases. Möller states that
moderate exercise or work stimulates the establishment of
collateral circulation. Massage per rectum is condemned as
dangerous by Cadiot.
Fracture of the Patella.
Etiology and Occurrence.--Patellar fractures are rarely met with in
the horse but may be caused by falls and heavy contusions. Violent
muscular contraction, it is said, may also bring about the same
condition.
Symptomatology.--Fracture may be transverse or vertical, and depending
on the manner in which the bone is broken, prognosis is either at once
rendered favorable or unfavorable. The patella performs a function which
is in a way similar to that of the sesamoids and when fractured,
complete recovery is improbable in the average instance. When complete,
transverse fractures permit of separation of the parts of bone. Tension
on the straight ligaments below and contraction of the quadriceps above
usually cause insuperable difficulty in the handling of this type of
fracture in the horse.
Compound fractures as well as multiple or comminuted fractures
occasionally occur and these constitute injuries which are generally
considered fatal, although Andrien, according to Cadiot and Almy,
succeeded in obtaining complete recovery in a case of compound fracture
of the patella and the horse was in service and almost free from
lameness two months after treatment was begun.
No difficulty is encountered in recognizing the fracture of the patella
because of the exposed position of the bone. Crepitation, and in some
cases fissures, may be easily detected.
Treatment.--In simple fracture, when treatment is thought advisable,
the subject is put in a sling and kept as nearly comfortable as
possible. If little inflammation exists, the application of a vesicant
two or three weeks after the injury has been inflicted will be helpful
and serve to hasten repair.
Bandages or mechanical appliances are of no practical use in the
handling of these cases.
Luxation of the Patella.
Etiology and Occurrence.--This, the most common luxation met with in
the equine subject, has been described by writers as existing in many
forms. Patellar disarticulation may be more practically considered as
_momentary_ and _fixed_, regardless of the position taken by the
patella. Described under the title of false luxation are recorded cases
wherein the quadriceps (crural) muscles become contracted in such manner
that a condition simulating true disarticulation of the patella obtains.
Also, some practictioners report cases of patellar luxation and refer to
pseudo-luxations, without clearly defining the conditions which
constitute pseudo-luxation. This has contributed to the extant cause of
misconception as to actual differences between luxation and conditions
simulating dislocation.
Luxation of the patella is a condition wherein the articular portions of
the femur and patella assume abnormal relations whether such
displacement of the patella be momentary and capable of spontaneous
reduction, or fixed and requiring corrective manipulation. Spasmodic
contraction of the crural muscles which sometimes retains the patella in
such position that the leg is rigidly extended, does not in itself
constitute luxation of the patella; and unless this bone becomes lodged
on the upper portion of a femoral condyle or laterally displaced out of
its femoral groove, luxation cannot be said to exist in the horse. These
are sub-luxations.
Occasionally one may observe in suckling colts outward luxation of the
patella wherein there is history of navel infection and no marked
evidence of rachitis is present. Some of these cases recover. In a
unilateral involvement of this kind in a three-month-old mule colt, the
author observed a case wherein an unfavorable prognosis was given and
destruction of the subject advised, because of the extreme dislocation
of the patella. This colt, however, was not destroyed and in three weeks
had apparently recovered. No treatment was given in this instance; the
colt was allowed the run of a small pasture with its dam and in time it
matured, becoming a sound and serviceable animal.
Classification.--Two forms of true patellar luxation in the horse may
be considered; one which is due to the patella becoming fixed upon the
internal trochlear rim of the femur and the other when the patella slips
over the outer rim of the trochlea.
The first form is known as _upward_ luxation and is made possible by
rupture of the mesial (internal) femeropatellar ligament. According to
Cadiot and Almy, it is only by the rupture of this ligament--the
femeropatellar--that upward luxation may occur. This type of luxation is
rarely observed and is usually due to violent strain and abnormal
extension of the stifle joint.
The second class, _outward_ luxation, occurs in colts and is, in many
instances, congenital. This form of luxation is also the one usually
seen following debilitating diseases such as influenza and pneumonia.
_Upward luxation of the patella_ is characterized by the stiff-extended
position of the leg. When the patella is situated upon the inner
trochlear rim, the tibia must be extended because of the traction
exerted by the straight ligaments. Since the stifle and hock joints
extend and flex in unison, there is presented also an extension of the
tarsus. Extension of the stifle joint would increase the distance
between the femoral origin of the gastrocnemius and its insertion to the
summit of fibular tarsal bone (calcis) were it not for the gastrocnemius
and superficial flexor (perforatus). Extension of the hock in upward
luxation of the patella, permits of flexion of the phalanges. In upward
luxation, then, the leg is extended as if too long, but the phalanges
may be in a state of moderate flexion. If the foot rests on the ground
when the extremity is not flexed, it is almost impossible for the
subject to step backward. Because of immobilization of the stifle and
hock joints in upward luxation, the subject can walk only by hopping on
the sound leg and then the extremity is flexed, allowing the anterior
portion of the fetlock to drag on the ground.
In some cases practitioners are called to attend young animals that are
reported to be "stifled" (often in young mules that have made a rapid
growth) and upon arrival the only noticeable symptom of preëxisting
luxation is the soiled condition of the anterior fetlock
region--evidence of its having been dragged. Such cases may be styled
momentary luxation, whether they are due to a weakened condition of the
patellar ligaments or spasmodic contraction of the crural muscles.
In upward luxation, reduction is effected by attempting further
extension of the stifle joint and at the same time the patella is pulled
outward, off the internal rim of the trochlea. This is attempted by
securing the subject in a standing position; the sound side is kept
against a wall if possible and a rope is tied to the extremity of the
affected leg. Traction is exerted upon the rope and at the same time
force is directed against the stifle joint to produce further extension
if possible, so that the straight patellar ligaments may relax
sufficiently to allow the patella to be dislodged from its position upon
the inner trochlear lip. Failing in this manner of procedure, the
affected animal is to be cast and anesthetized with chloroform. The
relaxation which attends surgical anesthesia will permit of reduction of
the dislocated bone and manipulations such as have just been outlined
may be employed.
Following reduction in the average case it is essential that the subject
be given vigorous exercise for a few minutes. Reduction having been
affected, the application of a vesicant over the whole patellar region
is customary.
In cases of habitual luxation, unless the ligaments are so lax that the
patella may be displaced laterally over the inner as well as the outer
trochler rims, division of the inner straight patellar ligament will
correct the condition. This desmotomy has been advocated by Bassi, and
good results in appropriate cases have been reported by Cadiot, Merillat
and Schumacher. This operation has been found a corrective in cases of
outward luxation as well as those of upward dislocation of the patella
when resorted to before the trochleae are worn from frequent luxation.
_Outward luxation of the patella_ is occasioned by a lax condition of
the internal femeropatellar ligament or a rupture of the same so that
the patella slips over the outer femoral trochlear rim and permits of an
abnormal flexion of the stifle joint. The outer trochlear rim being the
smaller of the two, inward luxation does not occur in the horse. With
the patella disarticulated in this manner, the action of the quapriceps
femoral group of muscles has no effect on the stifle joint and,
therefore, flexion of this articulation occurs as soon as the subject
attempts to sustain weight and the leg collapses unless weight is at
once taken up by the other member if sound.
As a rule, the reduction of this form of luxation is not difficult. The
patella may be pushed inward and into position without manipulation of
the leg. Retention of the patella in position is a difficult problem.
Bandaging is considered impractical and is not ordinarily done in this
country. Benard, according to Cadiot and Almy, recommends bandaging with
a heavy piece of cloth in which an opening is made through which the
patella is allowed to protrude, and by turning such a bandage snugly
about the stifle several times, the patella is held in position. This
bandage should be kept in place for about ten days.
In young and rachitic animals outdoor exercise and a good nutritive
ration for the subject are indicated. Hypophosphites in assimilable form
may be beneficial, and vesication of the patellar region contributes to
recovery.
Where extreme luxation is present in both stifles, the prognosis is
unfavorable. In such cases, degenerative changes may exist and in some
instances the ligaments are so diseased and elongated that regeneration
is impossible. Williams[46] reports a case where bilateral "floating"
(outward) luxation was present and extensive degeneration changes
affected the articulation.
In subjects suffering frequent dislocation of the patella (habitual
luxation) it is possible in some cases, to prevent its occurrence or at
least to minimize the distress occasioned by momentary luxation, by
keeping the animals in wide stalls so that "backing" is unnecessary. In
some nervous subjects that seem to be suffering from cramp of the crural
muscles, the difficulty and pain of their being backed out of narrow
stalls, accentuates the nervousness. Sudation and restlessness are
manifested and the subject presents a clinical picture of distress and
fear of a painful ordeal. In some cases of this kind, complete recovery
takes place by the time animals are five or six years of age. One should
avoid keeping such subjects in narrow stalls. Preferably patellar
desmotomy should be performed that relief may be obtained at once.
Luxations attending some cases of influenza recover promptly when
subjects are kept comfortably confined in roomy box-stalls. The
administration of stimulative medicaments such as nux vomica and the
application of an active blistering agent to the patella serve to hasten
recovery. Dislocations in such cases are often bilateral and they are
usually momentary. Reduction occurs spontaneously, as a rule, and the
subjects are not occasioned much distress if they are kept quiet for a
few days.
Chronic Gonitis.
Etiology and Occurrence.--Chronic inflammation of the stifle joint is
met with following acute synovitis due to strains and concussion. It is
an ailment which affects heavy horses and particularly animals that are
kept at work on paved streets, but this does not explain its existence
in animals that are not subjected to work likely to cause concussion.
Berns[47] considers rheumatism a probable cause of gonitis and, as he
states, the dropsical form of affection of this joint is not ordinarily
attended with manifestations of inconvenience to the subject. Gonitis is
often bilateral and its onset is insidious in many instances.
Symptomatology.--In unilateral gonitis weight is not borne by the
affected member. There is noticeable distension of the joint capsule--a
characteristic pendant pouching protrusion. When both stifles are
affected the subject frequently shifts the weight from one limb to the
other. Lameness comes on gradually and during the incipient stages may
be intermittent but it progressively increases so that in time affected
animals become useless. In bilateral affections animals drag the toes
because of the pain incident to flexing the stifles. This is
particularly evident when the subject is made to trot. As the disease
progresses, atrophy of the quadriceps femoris muscles becomes pronounced
and as destructive changes involving the articular cartilages take
place. The subject becomes more lame and eventually is rendered
incapable of service.
Upon manipulation of the patellar region, one is impressed with the fact
that hyperesthesia does not exist in proportion to the pain manifested
during locomotion. In some cases a gelatinous swelling is present and
may be detected by palpating between the straight ligaments of the
patella. Williams, Hughes, Merillat, Hadley and others have directed
attention to the existence of floating masses (_corpora oryzoidea_) in
the synovial capsule of this joint in gonitis, and as with all cases of
arthritis, irreparable damage is often done the articular cartilages
during the course of the ailment.
[Illustration: Fig. 50--Chronic gonitis. The knuckling which results
from long continued inactivity of the crural muscles in chronic cases is
marked in this instance. Photo by Dr. L.A. Merillat.]
Treatment.--No effective method is as yet known which will control
this condition during its incipiency. The disease progresses, and more
or less damage is done the affected parts in the course of months or
even years in some cases before subjects are rendered hopelessly
crippled. When recognized early (before chronic gonitis exists)
aspiration of the synovia and the injection of diluted tincture of iodin
might prove beneficial in cases of synovial distension. Chronic gonitis
is considered an incurable affection and as soon as subjects manifest
evidence of distress from this condition they should by all means be
taken from work. Firing and vesication have not been productive of
beneficial results.
[Illustration: Fig. 51--Gonitis. Showing position assumed in such cases
because of pain occasioned. Photo by Dr. C.A. McKillip.]
Open Stifle Joint.
Anatomy of the Joint Capsule.--This joint capsule is thin and very
capacious. On the patella it is attached around the margin of the
articular surface, but on the femur the line of attachment is at a
varying distance from the articular surface. On the medial side it is an
inch or more from the articular cartilage; on the lateral side and
above, about half an inch. It pouches upward under the quadriceps
femoris for a distance of two or three inches, a pad of fat separating
the capsule from the muscle. Below the patella it is separated from the
patellar ligaments by a thick pad of fat, but inferiorly it is in
contact with the femerotibial capsules. The joint cavity is the most
extensive in the body. It usually communicates with the medial sac of
the femerotibial joint cavity by a slit-like opening situated at the
lowest part of the medial ridge of the trochlea. A similar, usually
smaller, communication with the lateral sac of the femerotibial capsule
is often found at the lowest part of the lateral ridge. (Sisson's
Anatomy.)
Thus it is seen that because of its frequent communication with the
other parts of this large synovial membrane, a wound which opens the
external portion of the femerotibial capsule may be the cause of
contamination and resultant infectious arthritis of the whole stifle
joint. Because of the distance between the most dependent part of the
femerotibial articulation and the summit of the patella, one may
misjudge the exact location of the lowermost part of this portion of the
capsular ligament of the stifle joint and thereby fail at once to
appreciate the seriousness of calk wounds in this region.
Etiology and Occurrence.--Wounds to the patellar region are of rather
frequent occurrence, and because of the comparatively unprotected
position of these structures, the capsular ligaments of the stifle joint
may be perforated as a result of violence in some form. Calk wounds
which penetrate the tissues in the immediate region of the lower portion
of the external part of the femerotibial capsule sometimes result in
open joint because of tissue necrosis resulting from the introduction of
infection. Contused wounds sometimes destroy the skin and fascia over
large areas on the lateral patellar region and because of subsequent
sloughing of tissue due to infection as well as to the manner in which
such wounds are inflicted, septic arthritis subsequently occurs.
Penetrant wounds, such as may be caused by a fork tine may not result in
infection; if infectious material is introduced an infectious arthritis
does not necessarily follow, though such cases should be considered as
serious from the outset.
Symptomatology.--The pathognomonic symptom of open stifle joint is the
profuse escape of synovia, indicating perforation of the synovial
capsule; by means of a probe the wound may be explored in a way that
will clearly reveal the nature of the injury.
After a few days have elapsed in cases where considerable infection has
taken place, there is manifestation of pain as in all cases of infective
arthritis. Hughes[48] gives an excellent description of the clinical
aspect of arthritis which applies here:
Acute arthritis begins like an ordinary attack of synovitis. In
joints other than the pedal and pastern, there is sudden and
extensive swelling, which at first is intra-articular, succeeded by
extra-articular tumefaction, and accompanied by violent lameness.
The pain soon becomes intense and agonizing. There is severe
constitutional disturbance, the temperature ranging from 104 to 106
degrees and the pulse from 60 to 72. Painful convulsions of the
limb occur, shown by involuntary spasmodic elevations due to reflex
irritation of the muscles. There is loss of appetite, rapid
emaciation, the flank is tucked up and the back arched. In from
three to six days, the tumefaction around the joint tends to soften
at a particular place, and bursts, and a discharge that is
sometimes of a sanious character, mixed with synovia, escapes.
Great exhaustion at times supervenes, and if the joint is an
important one, the horse lies or falls and is unable to rise.
Treatment.--In small puncture wounds the immediate application of a
vesicating ointment has given good results, but when infection has taken
place to such extent that the animal manifests evidence of intense pain,
and lameness is marked and local swelling and hyperesthesia are great,
vesication is contraindicated. In such instances the exterior of the
wound and its margins should be prepared as in similar affections of
other joints. A quantity of synovia is then aspirated by means of a
small trocar and care should be taken to observe all due aseptic
precautions. Subsequently the injection of from four to six ounces of a
mixture of tincture of iodin, one part to ten parts of glycerin, and
gentle massage of the joint immediately after the injection has been
made, serves to check the infective process in some cases.
The subject should be cared for as has been previously suggested in
arthritis proper provisions for comfort being made. Good nursing is
always essential to a successful issue. However, the author cannot view
cases of open stifle joint with the same optimism concerning their
course and outcome that is expressed by a number of writers on this
subject. It is a grave condition wherein the prognosis should be given
advisedly.
Fracture of the Tibia.
Etiology and Occurrence.--Because of its exposed position to kicks,
and its lack of protection by heavy musculature (especially on its inner
surface), there is afforded ample opportunity for frequent injury to the
tibia. Fractures are complete and varying as to nature, or incomplete.
The heavy tibial fascia affords sufficient protection so that fissures
without entire solution of continuity of the bone may occur from
violence to which this part is often subjected. Möller classes tibial
fracture as ranking second in frequency--pelvic fracture being more
often met with in horses. This does not apply in our country as
phalangeal and metacarpal and even metatarsal fractures are observed in
more instances than are such injuries to the tibia. The tibia is
occasionally broken at its middle and lower thirds, but malleolar
fractures are not common.
Symptomatology.--When fracture is complete and all support is removed,
the leg dangles, and the nature of the injury is so obvious that there
is no mistaking its identity. However, in case of incomplete fracture
one needs to base all conclusions upon the history of the case, evidence
of injury, or other knowledge of the character of violence to which
this bone has been exposed. For without the presence of crepitation
(even by excluding other possible causes for the pronounced lameness
which characterizes some of these cases) we can only resort to the
knowledge which experience has taught that fracture may be deemed
probable in many injuries to the tibial region. Consequently, we are to
look upon all injuries that affect the tibia as being fractures of some
sort when there is either local evidence of the infliction of violence
or whenever marked lameness attends such injuries, unless there is
positive indication that no fractures exist.
A careful examination of parts of the tibia, i.e., noting the amount and
painfulness of swellings, exploration with the probe, and observations
of the course taken in any given case, will determine the exact nature
of injuries. Such examination needs to extend over a period of a week or
in some instances two or three weeks may pass before the true state of
affairs is apparent. In the meanwhile, cases are to be handled as though
tibial fracture certainly existed.
Prognosis.--Prediction of the outcome in tibial fracture is somewhat
presumptuous, but in the majority of cases in mature subjects fatality
results. Cadiot[49], however, views this condition with more optimism
than have American practitioners. While he considers the condition
grave, in citing case reports of successful treatment by d'Arboval,
Duchemin, Leblanc, and others, his conclusion is that many practitioners
erroneously consider fractures of the tibia as incurable.
The method of handling these cases by Leblanc is as follows: The subject
is placed in a sling; a pit is excavated below the affected member so
that a heavy weight may be attached to the extremity; splints are
applied to each side of the leg, which is padded with oakum, and this is
kept in position by means of bandages covered with pitch. The outer
splint extends from the hoof to the stifle and the inner one from the
hoof to the upper third of the leg. This method in the hands of Leblanc
has been successful in several instances, according to Cadiot.
In a foal the author has in one instance succeeded in obtaining complete
recovery in a simple fracture of the lower third of the tibia where the
only support given the broken bone was a four-inch plaster-of-paris
bandage which was adjusted above the hock. Below the tarsus a cotton and
gauze bandage was applied to prevent swelling of the extremity. In this
instance (an emergency case in which materials that are not to be
recommended were necessarily employed) recovery took place within thirty
days.
As has been mentioned in the consideration of radial fractures, heavy
leather is better suited for immobilization of these parts than a cast
or other rigid splint materials. Mature animals may be expected to
resist the immobilization of the hind legs because of the normal manner
of flexion of the tarsal and stifle joints in unison. Therefore, the
application of rigid splints to the leg and including the hock is
productive of disastrous results in some cases.
The application of cotton and bandages to pad the member and the
adjusting of heavy leather splints on either side of the leg, and
retaining them in position with four-inch gauze bandages will prove more
nearly satisfactory than some other methods employed. Prognosis is
unfavorable, however, in most cases of compound fracture and recovery is
improbable when the upper portion of the tibia is broken.
Rupture and Wounds of the Tendo Achillis.
Etiology and Occurrence.--Cases are recorded by Uhlrich in which
rupture has followed degenerative changes affecting the tendo Achillis.
Not infrequently, the result of a trauma, division of the tendo Achillis
occurs. Möller states that rupture of this tendon may be due to jumping,
in riding horses and in draught horses, in their efforts to avoid
slipping. In runaways, it sometimes occurs where sharp-edged implements
are bounced against the legs in such fashion that division of the tendon
results.
Symptomatology.--With division of the tendo Achillis or of the
musculature of the gastroenemii and the superficial flexor
(perforatus), there remains nothing to inhibit tarsal flexion except the
deep flexor tendon (perforans) and this does not support the leg. When
attempt is made to sustain weight with the affected member, abnormal
flexion of the tarsus takes place and the hock sinks almost to the
ground. The symptoms are so characteristic that recognition is always
easy even in case no wound of the skin exists.
Prognosis.--Spontaneous recoveries occur and such cases are reported
by Bouley who is quoted by Cadiot as having observed division of the
tendo Achillis due to a sword wound wherein at the end of four months
recovery was complete. Division of this tendon in brood mares has been
practiced by the early settlers of parts of the United States for the
purpose of preventing their straying too far from home. In such
instances one leg only was so mutilated and in most instances, it is
reported that spontaneous recovery took place.
In unilateral involvement without complications, the prognosis is not
unfavorable if provisions for giving necessary attention are available.
Treatment.--The subject is to be confined in a sling and the member
bandaged and supported by means of leather splints. Immobilization as
for fracture is not necessary but, nevertheless, movement is to be
restricted as much as possible. In case of open wounds, the exposed
tissues are cared for along general surgical lines. Where the divided
parts of the tendon are maintained in fairly close and constant
relation, granulation of tissue, sufficient to sustain weight takes
place in from six weeks to three months.
Spring-Halt. (String-Halt.)
Occurrence.--This condition is a myoclonic affection of the hind leg
which is discussed in works on theory and practice under the head of
neuroses, but the cause or causes have not been established. Theories
that heredity is responsible have their supporters and advocates of
hypotheses attributing it to disease of the sciatic nerve, patellar
subluxation, fascial contraction of various muscles, "dry spavin"
(tarsal arthritis), iliac exostoses, disease of the foot and contraction
of the hoof, are on record in veterinary literature. This ailment
affects old horses more frequently than it does young and is seen in all
breeds of animals including mules.
[Illustration: Fig. 52--Spring-halt.]
Symptomatology.--This disease develops slowly, and progressively
increases in severity as a rule, but does not ordinarily constitute
cause for rendering an animal unserviceable. While the affection is
sometimes bilateral (occasionally affections of the forelegs are
reported) and the extreme flexion of the legs in the spasmodic manner
which characterizes spring-halt, cause great waste of energy during
locomotion, yet such cases are rare. Usually the ailment is markedly
evinced when subjects are first taken from the stable, but as they are
exercised the manifestation diminishes, and in many instances it
completely subsides. The condition is generally more noticeable when the
subject is made to step backward. In some animals there is marked
abduction at the time flexion occurs and in singular instances the
spasmodic contraction is so violent that the subject falls to the ground
as a result of the peculiar flexion of the leg.
In severe cases of "scratches" or chemical irritation of the extremity,
the legs are abnormally flexed in a manner which simulates spring-halt,
but because of the evident injury of the parts this is not likely to
confuse. Since all facts concerning etiological agencies are surrounded
with so much obscurity, classification does not lend any particular
assistance in the consideration of this ailment.
Prognosis.--One cannot intelligently give a prognosis in these cases
if forecast is expected to state the exact course following treatment.
However, in a general way, cases of recent affection are thought more
favorable than are those of long standing or in old animals where
myositis and other muscular and fascial affections exist owing to years
of hard service.
Treatment.--No known line of medicinal treatment is of service, nor is
any particular surgical operation to be considered dependable for
obtaining relief. Operations of almost every conceivable nature have
been tried with the hope of securing recovery in spring-halt but under
no condition can the practitioner as yet be reasonably certain of
effecting permanent relief in any case. Treatment is, therefore,
entirely empirical.
Neurectomies have been performed and recoveries following were
attributed thereto; fascial divisions in the crural region have been
done with good results and this manner of treatment has its favorers.
Advocates of tenotomies, likewise, are to be found. Consequently, one
may summarize thus: Spring-halt is a disease of unknown origin--the
exact cause has not been determined; therefore, all treatment is, in a
way, experimental. The recommendation of any given procedure in handling
cases must then be a matter of opinion based either upon practical
experience or knowledge of the experiences of others. Divisions of the
lateral digital extensor (peroneus) below the tarsus near its point of
insertion to the extensor of the digit is recommended here because it is
followed by a percentage of recoveries that is as large as in any other
method of treatment and the operation is not difficult to perform nor
is its performance fraught with any dangerous complications. In selected
subjects about fifty per cent of cases recover in from two to six weeks
following this operation.
[Illustration: Fig. 53--Lateral (external) view of tarsus showing
effects of generalized tarsitis.]
Open Tarsal Joint.
Like the tibia the hock is exposed to frequent injuries and in some
cases wounds perforate the joint capsule. When due to calk wounds where
horses are kicked, the injury is often on the side of the tarsus (medial
or lateral) and such wounds not infrequently result in infectious
arthritis. Horses sometimes jump over wire fences and wounds are
inflicted which constitute extensive laceration of the joint capsule. In
firing for bone spavin, where a deep puncture is made very near the
tibial tarsal (tibioastragular) joint if infection gains entrance,
serious and generalized infection of the open joint cavity supervenes in
some cases.
Symptomatology.--There is no marked difference in the constitutional
disturbances which are occasioned in this condition and those
encountered in other cases of septic arthritis (previously considered
herein) except that there is a difference in the degree of resultant
derangement and local tissue changes. Chiefly, because of the difficulty
encountered in keeping the hock joint in an aseptic condition or
securely bandaged, open tarsal joint constitutes a more serious
condition than a similar affection of the fetlock. Otherwise, a very
similar condition obtains and the same diagnostic principles serve here
that have been described on page 110 in considering open fetlock joint.
Treatment.--The same plan that is described in detail for treatment of
similar conditions affecting the fetlock joint is indicated in this
affection. Exceeding care must be exercised in bandaging the hock,
however, lest the animal be so irritated that in the extreme flexion of
the tarsus which is often caused by bandaging, the wound dressings may
be completely deranged. A wide gauze bandage material is most
satisfactory; cotton of long fiber is separated in thin layers and wound
about the hock, extending from the site of injury to a point about six
inches proximal to the summit of the os calcis. By using an abundance
of cotton in this way, it will not be found necessary to apply the
bandages very snugly; with a four-inch gauze bandage material, which is
supported above the cap of the hock and brought across the anterior face
of the tarsus in a diagonal manner, a comfortable and very serviceable
protective dressing is provided for. Animals so treated will not
ordinarily resist because of pressure from the bandages. Pressure is
unavoidable in the use of adhesive dressings or where careful attention
is not given the manner of applying cotton to the parts. Such methods
are sure to result disastrously. But if subjects are kept quiet after
the parts have been properly bandaged, no difficulty is encountered in
maintaining asepsis in an uninfected wound. Recovery takes place in
favorable cases in from three weeks to three months, depending on the
nature and extent of injuries inflicted.
Fracture of the Fibular Tarsal Bone (Calcaneum.)
Etiology and Occurrence.--This condition though rarely met with in the
horse, is the result of violent strain upon the os calcis by the
gastrocnemius and superficial flexor tendons in efforts put forth by
animals in attempts to regain a footing when the hind feet slip forward
under the body, or in jumping and in falls or direct contusion by heavy
bodies. Hoare[50] reports a case of a mare that had produced fracture in
jumping.
Fracture of the other tarsal bones are very seldom observed but may be
occasioned by contusions wherein multiple or comminuted fractures are
produced, such as are to be seen in small animals. Fracture of the
tibial tarsal bone (astragalus) is to be observed as a complication in
luxations of the tarsal joint and, according to Cadiot, the other tarsal
bones may likewise suffer fracture in luxations of the hock.
Symptomatology.--Great pain attends this accident according to the
observations given in recorded cases. In the case cited by Hoare the
animal evinced great pain and uneasiness; the hock was unduly flexed;
the calcaneum was displaced forward; and marked crepitation was present.
A portion of the body of the calcaneum was protruding through the
perforated skin. The animal was destroyed and the bone was found broken
in three pieces.
[Illustration: Fig. 54--Right hock joint. Viewed from the front and
slightly laterally after removal of joint capsule and long collateral
ligaments. T.t., Tibial tarsal bone (distal tuberosity). T.c., central
tarsal bone. T.3. Ridge of third tarsal bone. T.f. Fibular tarsal bone
(distal end). T.4. Fourth tarsal bone. Mt. III, Mt. IV. Metatarsal
bones. Arrow points to vascular canal. (From Sisson's "Anatomy of the
Domestic Animals.")]
Since the support for the tendo Achillis is removed in such fracture and
no leverage on the metatarsus obtains, it naturally follows that any
attempt to sustain weight must result in extreme flexion of the hock and
descent of this part in a manner similar to cases of rupture or division
of the Achilles' tendon. The two conditions should not be confused,
however, as the parts may be definitely outlined by palpation and the
slack condition of the tendon and displaced summit of the calcaneum,
which characterize fracture of the fibular tarsal bone, are easily
recognized.
Treatment.--Prognosis is unfavorable in the majority of cases, but
should attempts at treatment be undertaken in young and quiet mares
which might prove valuable for breeding purposes in case of imperfect
recovery, they should be put in slings and the member is to be
immobilized as in tibial fracture. Authorities are agreed that prognosis
is entirely unfavorable in mature animals, when the case is viewed from
an economic standpoint.
Tarsal Sprains.
Etiology and Occurrence.--The hock joint is often subjected to great
strain because of the structural nature of this part and its relation to
the hip as well as the manner in which the tarsus functionates during
locomotion. That ligamentous injuries owing to sprain frequently occur
and attendant periarticular inflammations with subsequent hypertrophic
changes follow, is a logical inference. Fibrillary fracture of the
collateral ligaments may take place in falls or when animals make
violent efforts to maintain their footing on slippery streets. In
expressing opinions concerning the frequency with which the hock is
found to be the seat of trouble in lameness of the pelvic members,
different writers place the percentage of hock lameness at from
seventy-five to ninety per cent. And when one considers the possibility
that a goodly proportion of cases of tarsal exostis are the outcome of
sprains, the occurrence of tarsal sprains may be more generally
admitted.
Symptomatology.--A mixed type of lameness is present and the nature of
the impediment varies, depending upon the location of the injury.
Sprains of the mesial tarsal ligaments cause lameness somewhat similar
to that of spavin. However, in establishing a diagnosis, local evidence
in these cases is of greater significance than the manner of locomotion.
During the acute stage of inflammation there is to be detected local
hyperthermia, some hyperesthesia and a little swelling. Later, when
resolution is not prompt, considerable swelling (or perhaps correctly
speaking, an indurated enlargement) variable in size is developed. In
some cases the entire tarsal region becomes greatly enlarged and this
swelling is very slowly absorbed in part or completely. Such sub-acute
cases are observed during the winter season and particularly where
subjects are kept in tie stalls without exercise for weeks at a time.
Treatment.--Attention should be directed toward relief for the animal
in all acute inflammations. Local applications of heat are helpful and,
of course, rest is essential. Towels that are wrung out of hot water and
held in position by means of a few turns of a loose bandage and this
covered with an impervious rubber sheet, will serve as a practical means
of application of hydrotherapy. Following this when conditions improve,
as in the handling of all similar cases, counterirritation is indicated.
When proper care is given at the onset and where injury does not involve
too much ligamentous tissue, recovery takes place in a few weeks but in
some cases which occur during the winter season in farm horses, complete
recovery does not result until several months have passed.
Curb.
The hock is said to be curbed when the normal appearance, viewed from
the side, is that of bulging posteriorly at any point between the summit
of the calcaneum and the upper third of the metatarsus. Among some
horsemen a hock is said to be "curby" whenever there exists an
enlargement of any kind on the posterior face of the tarsus whether it
be due to sprain, exostosis or proliferation of tissue as a result of
contusion.
French veterinarians consider under the title of "courbe," an exostosis
situated on the mesial side of the distal end of the tibia. Cadiot and
Almy state that this condition (courbe) is of rare occurrence. Percivall
defines curb as "a prominence upon the back of the hind leg, a little
below the hock, of a curvilinear shape, running in a direct line
downwards and consisting of infusion into, or thickening of, the sheath
of the flexor tendons." Möller's version of true curb is a thickening of
the plantar ligament (calcaneocuboid or calcaneometatarsal). Hughes and
Merillat consider curb as a synovitis having for its seat the synovial
bursa which is situated between the superficial flexor tendon
(perforatus) and the plantar ligament.
Occurrence.--Certain predisposing factors seem to favor the occurrence
of curb. A malformation of the inferior part of the tarsus so that its
antero-posterior diameter is considerably less than normal is a
contributing cause. Such hocks are known as "tied-in." Another fault in
conformation is the existence of a weak hock that is set low down on a
crooked leg, especially when such a member is heavily muscled at the
hip. Given such conformation in an excitable horse, and curb is usually
produced before the subject is old enough for service. It is certain
that in cases where conformation is bad, greater strain is put upon the
plantar ligament. This structure serves to bind the tibial tarsal
(calcis) bone to the metatarsus; traction exerted upon its summit by the
tendo Achillis is great when animals run, jump or rear and also at heavy
pulling. In animals having curby hocks, sprain is likely to result and
curb supervenes.
Symptomatology.--The characteristic swelling which marks curb may
develop quickly and lameness occur suddenly or the enlargement comes on
gradually and slowly, causing little lameness. Lameness is not
proportionate to the size of the swelling and in all cases whether
subacute or chronic, the condition improves with rest, but lameness is
again manifested upon exertion. A horse which "throws a curb" will go
lame until the acute inflammatory condition subsides and depending upon
treatment received and conformation of the hock, this requires from
three days to two or three weeks.
The character of the swelling varies; in some cases it is not large but
rather dense and lacking in evidence of heat and hyperesthesia; in other
cases there is considerable swelling, which is hot and doughy, somewhat
painful to the touch but not necessarily productive of much lameness. In
any event, whether the swelling or enlargement is big or little, its
location makes it conspicuous when viewed in profile.
In most cases after the acute inflammatory period has passed, lameness
is slight, if at all present, and in time no interference with the
subject's usefulness is occasioned because of the curb, but the animals
often remain blemished--complete resorption of inflammatory products
being unusual when much disturbance has existed.
Treatment.--The handling of curb during the acute inflammatory stage
is along the same lines as in sprain--local applications of cold and
heat. Subjects must be kept quiet until all inflammation has subsided,
for there are no cases wherein a little brisk exercise is more likely to
cause a recurrence of lameness before recovery is complete than in curb.
Vesication is in order in a week or ten days after the affection has set
in; in old stubborn cases that have resisted ordinary treatment for a
few months, the use of the actual cautery (line firing) is to be
recommended.
[Illustration: Fig. 55--Spavin.]
Spavin. (Bone Spavin.)
This term is applied to an affection of the tarsus which is usually
characterized by the existence of an exostosis on the mesial and
inferior portion of the hock. There is also included under this name,
articular inflammation wherein no external evidence is shown. Spavin
lameness has long been recognized and much has been written upon this
subject. Since authorities are agreed that most cases of lameness in the
hind leg are due to hock affection, and because the majority of cases of
lameness which have the tarsal region as the seat of trouble are
instances of spavin lameness, this disease merits all the attention it
has received.
Etiology and Occurrence.--Causes may well be classified as
predisposing and exciting, for there are many etiologic factors to be
reckoned with in spavin, some of which are widely different in nature.
Considered as predisposing causes, hereditary influences play an
important rôle and may, owing to faulty conformation, subject an animal
to affections of this kind because of disproportionate development of
parts (weak and small joints and heavy muscular hips); or as a
consequence of inherited traits, a subject may manifest susceptibility
to degenerative bone changes which are signalized by the formation of
exostoses of different parts on one or more of the legs. Hereditary
predispositions make for the presence of spavin in a large percentage of
the progeny of sires so affected. This fact has been repeatedly
demonstrated in this country as well as elsewhere according to Quitman,
Dalrymple and Merillat.[51] A number of states have passed stallion
inspection laws stipulating that animals having such exostoses as spavin
and ringbone cannot be registered except as "unsound."
Asymmetrical conformation, particularly where the hock is obviously
small and weak as compared with other parts of the leg, constitutes a
noteworthy predisposing cause.
Peters' theory is plausible that the screw-like joint between the tibia
and the tibial tarsal (astragulus) bones causes these structures to
functionate in a manner not in harmony with the provisions allowed by
the collateral ligaments of the tarsus, permitting movement only in a
direction parallel with the long axis of the body.
Because of the quality of their temperaments, nervous animals possessing
no particular congenital structural defects of the hock and having no
history of spavined progenitors, are subject to spavin when kept at work
likely to produce tarsal sprain. Spavin usually develops early in such
subjects and examples of this kind may be frequently observed in
agricultural sections of the country. Where spavin develops in unshod
colts at three and four years of age, shoeing is not an influencing
agency when animals are not worked on pavements.
Exciting causes of spavin are sprain and concussion. Various hypotheses
are recorded as to how sprains are influenced and among others may be
mentioned that of McDonough[52], which is that the foot is robbed of its
normal manner of support by the ordinary three-calked shoe. With such a
shoe, little support is given the sides of the foot; hence, undue strain
is put upon the collateral ligaments of the tarsus. Moreover, the shoe
with its calks increases the length of the leg and adds to the leverage
on the hock, by virtue of such added length. This makes for greater
strain upon the mesial or lateral tarsal ligaments whenever the foot
bears upon a sloping ground surface, so that one side (inner or outer)
is higher or lower than the other. But according to McDonough's theory
(a good one concerning horses that work on pavements), the chief error
in shoeing lies in that the foot is deprived of its normal base or
support on the sides--the three-calked shoe being an unstable
support--and that this manner of shoeing city horses working on
pavements is an "inhumane" practice, a "diabolical method."
Whether spavin has its point of origin within the articulation as a
rarefying ostitis of the cancellated structure of the lower tarsal bones
as suggested by Eberlein; or, as Diekerhoff asserts, that the cunean
bursa may be the initial point of affection, is unsettled; but it is
reasonable to consider occult spavin as having its origin within the
articulation, and that cases readily yielding to cunean tenotomy are
primarily due to affection of the cunean bursa.
Symptomatology.--Where a visible exostosis exists, the presence of
spavin is easily detected, yet exostoses that extend over large areas
may constitute cause for serious trouble and still be difficult of
detection. By observing the internal surface of the hock from various
suitable angles, such as from between the forelegs or directly behind
the subject, one may note the presence of any ordinary exostosis.
The position assumed by the spavined horse is often characteristic. More
or less knuckling is usually present (Liautard, McDonald). There is
abduction of the stifle in some cases, or the toe may be worn in unshod
horses so that it presents a straight line at the surface. This is
manifested to a great degree in some animals and in others the foot is
not dragged and there is no wearing of the hoof at the toe.
Spavin lameness is so distinctive that one trained and experienced in
the examination of horses that are spavined, should correctly diagnose
the condition in practically every instance without recourse to other
means than noting the peculiar character of the gait of the subject.
Lameness develops gradually in the majority of instances, and an
important feature in spavin lameness is that it disappears after the
subject has gone a little way, to return again as soon as the animal has
rested for a variable length of time--from a half hour to several hours.
This "warming out" is marked during the incipient stage, but less
pronounced in most chronic cases. A complete disappearance of lameness
is observed in some instances, while in others only partial subsidence
is evident. Because of the fact that pain is occasioned both during
weight bearing and while the leg is being flexed and advanced, there is
manifested the characteristic mixed lameness and exaggerated hip action
which typifies spavin. By throwing the hips upward with the sound member
it is possible to advance the affected leg with less flexion, hence less
pain is experienced in this manner of locomotion. When made to step
aside in the stall, a spavined horse will flex the affected member
abruptly and when weight is taken on the diseased leg, symptoms are
evinced of pain, and weight is immediately shifted to the sound limb.
This is marked during the incipient stages of spavin. Lameness usually
precedes the formation of exostosis, though cases are observed wherein
an exostosis is present and no lameness is manifested and no history of
the previous existence of lameness is available.
The "spavin test" is of value as a diagnostic measure when it is
employed with other means of examination, though reaction to this test
is seen in some cases in old "crampy" horses that have experienced hard
service. The test consists in flexing the affected leg (elevating the
foot from the ground twelve to twenty-four inches) and holding the
member in this position for a minute, whereupon the animal is made to
step away immediately at a trot. During the first few steps taken
directly thereafter, the subject shows pronounced lameness and this
constitutes a reaction to the spavin test.
Where no exostosis is present it becomes necessary to exclude other
causes for lameness but the characteristic spavin lameness is to be
relied upon to a greater extent in such cases than are other means of
examination. Such cases are known as occult spavin and may be present
for months before any external changes in structure are observable. In
some instances no extoses form even during the course of years. The
spavin test is of aid in establishing a diagnosis here but the marked
"warming out" peculiar to spavin is not so pronounced in such cases.
Prognosis.--An animal having hereditary predisposition to spavin is
not likely to recover completely whether this predisposition be due to
faulty conformation or susceptibility to bone changes. In predicting the
outcome, the temperament of the subject is to be taken into account, as
well as the character of service the animal is expected to perform. And
finally, a very important feature to be noted, is the location of the
exostosis. If situated rather high and extending anterior to the hock,
there is less likelihood of recovery resulting than where an exostosis
is confined to the lower row of tarsal bones. When situated anterior to
the tarsus a large exostosis may by mechanical interference to function,
cause lameness when all other causes are absent. In making examinations
one must not be deceived by the inconspicuous and seemingly
insignificant exostosis which has a broad base. In some cases of this
kind, dealers style the condition as "rough in the hock" when as a
matter of fact, in some instances, incurable spavin lameness develops.
Treatment.--Many incipient cases of spavin yield to vesication and a
protracted period of rest. Results depend primarily upon the nature of
the affection. However, in every instance if there is involvement of the
tibial tarsal (astragalus) bone, complete recovery is highly improbable.
When the disease is confined to the lower tarsal bones, lameness
subsides as soon as the degenerative changes are checked and ankylosis
occurs.
The use of the actual cautery when properly employed constitutes an
excellent method of treatment. The "auto-cautery" when equipped with a
point of about one-eighth of an inch in diameter and about three-fourths
of an inch in length is well suited for this particular operation.
Before deciding to cauterize, it is necessary to ascertain the extent of
area affected. The nearness of the exostosis to the tibiotarsal
articulation can be definitely determined by palpation. The hair over
the entire surgical field is clipped and the cautery at white heat is
pushed through the overlying soft tissues and into the central part of
the exostosis. Care is taken to keep the cautery-point away from the
articular margin of the tibial tarsal bone about three-fourths of an
inch. No danger will result from cauterizing to a depth of three-fourths
of an inch in the average case. Two or three (and not more) centrally
located points for penetration with the cautery are sufficient.
Experience has shown that several (five or six or more) punctures are
not productive of good results. When considerable cicatricial tissue is
present, due to the action of depilating vesicants or other chemicals,
sloughing of tissue is very apt to follow deep cauterization, if one is
not careful to keep the punctures at least one-half inch apart when
three are made. It is best, in such cases, to make but two deep
penetrations with the cautery but additional superficial punctures may
be made if kept about three-fourths of an inch distant and not nearer
than this to one another. Sloughing of tissue is not necessarily
productive of bad results but there is occasioned an open wound which
usually becomes infected and necrosis of tissue may extend into the
articulation. No benefit results from sloughing and it should be
avoided. In small horses, one deep point of cauterization is sufficient
if the osseous tissues are penetrated to a proper depth so that an
active inflammation is induced. The cautery may, if necessary, be
reintroduced several times. When the field of operation has been
properly prepared and it is thought advisable (as where subjects are
kept in the hospital for a time), the hock may be covered with cotton
and bandaged and no chance for infection will occur.
After cauterization the subject should be kept quiet in a comfortable
stall for three weeks; thereafter, if the animal is not too playful, the
run of a paddock may be allowed for about ten days and a protracted rest
of a month or more at pasture is best. It is unwise in the average case
to put an animal in service earlier than two months after having been
"fired."
Where cases progress favorably, lameness subsides in about three weeks
after cauterization and little if any recurrence of the impediment is
manifested thereafter. However, because of violent exercise taken in
some instances when subjects are put out after being confined in the
stall, a return of lameness occurs and it may remain for several days or
in some cases become permanent. No good comes from the use of blistering
ointments immediately after cauterization. The actual cautery is a means
of producing all necessary inflammation and it should be so employed
that sufficient reactionary inflammation succeeds such firing. The use
of a vesicating ointment subsequent to cauterization invites infection
because of the dust that is retained in contact with the wound. The
employment of irritating chemicals in a liquid form following firing is
needless and cruel.
In many instances lameness is not relieved and subjects show no
improvement at the end of six weeks time and it then becomes a question
of whether or not recovery is to be expected even with continued rest
and treatment. As a rule, such cases are unfavorable. In one instance
the author employed the actual cautery three times during the course of
six months and lameness gradually diminished for a year. In this case
the spavin was of nearly one year's standing when treatment was
instituted. The subject was a nervous and restless but well-formed
seven-year-old gelding. Recovery was not complete; recurrent intervals
of lameness marked this case, but the horse limped so slightly that the
average observer could not detect its existence after the animal had
been driven a little way.
Cunean tenotomy has been advocated and practiced by Abildgaard, Lafosse,
Peters, Herring, Zuill and others and good results have followed in many
cases so treated.
Considering results, the employment of chemicals of various kinds for
the purpose of relieving spavin lameness does not compare favorably with
firing. Moreover, so many animals have been tortured and needlessly
blemished in the attempted cure of spavin that agents which are not of
known value, the use of which are likely to result in extensive injury
to the tissues, are only to be condemned.
When spavin is bilateral and lameness is likewise affecting both
members, prognosis is at once unfavorable. Such cases are often
benefited by cauterization but only one leg at a time should be treated.
Bossi's double tarsal neurectomy (division of the anterior and posterior
tibial nerves) has undoubtedly been of decided benefit in many cases,
but is not at present a popular method of treatment in this country.
This operation has its indications, however, and may be recommended in
chronic lameness where no extensive exostosis exists which may
mechanically interfere with function.
Distension of the Tarsal Joint Capsule. (Bog Spavin.)
Distension of the capsular ligament of the tibial tarsal
(tibioastragular) joint with synovia is commonly known as bog spavin.
This condition is separate and distinct from that of distension of the
sheath of the deep flexor tendon (perforans) though not infrequently the
two affections coexist.
Etiology and Occurrence.--Following strains from work in the harness
or under the saddle, horses develop an acute synovitis of the hock
joint, which often results in chronic synovial distension. Debilitating
diseases favor the production of this affection in some animals. It is
also frequently observed in young horses and in draught colts of twelve
to eighteen months of age. This condition occurs while the subjects are
at pasture and often spontaneous recovery results by the time the
animals are two years of age.
[Illustration: Fig. 56--Bog spavin. Showing point of view which may be
most advantageously taken by the diagnostician in examining for
distension of the capsular ligament of the tarsal joint.]