NINTH ANNUAL YEAR BOOK— PART X 447 
surface may become the seat of the osseous deposit, and involve the 
articular face of all the bones of the hock, and this again is a bone 
spavin. There would seem, then, to be but little difficulty in compre- 
hending the nature of a bone spavin, and there Vvould be none but for 
the fact that there are similar affections which might confuse one if the 
diagnosis is not very carefully made. 
But the hock may be "spavined," while to all outward observation it 
still retains its perfect form. With no enlargement perceptible to sight 
or touch the animal may yet be disabled by an occult spavin, an anchylo- 
sis in fact, which has resulted from a union of several of the bones of 
the joint, and it is only those who are able to realize the importance of 
its action to the perfect fulfillment of the function of locomotion by the 
hind leg who can comprehend the gravity of the only prognosis which 
can be justified by the facts of the case — a prognosis which is essentially 
a sentence of serious import in respect to the future usefulness and value 
of the animal. For no disease, if we except those acute inflammatory 
attacks upon vital organs to which the patient succumbs at once, is more 
destructive to the usefulness and value of a horse than a confirmed 
spavin. Serious in its inception, serious in its progress, it is an ailment 
which when once established, becomes a fixed condition which there is 
no known means of dislodging. 
Cause. — The periostitis, of which it is nearly always a termination is 
usually the effect of a traumatic cause operating upon the complicated 
structure of the hock, such as a sprain which has torn a ligamentous 
insertion and lacerated some of its fibers; or a violent effort in jumping, 
galloping, or trotting, to which the victim has been compelled by the 
torture of whip and spur while in use as a gambling implement by a 
sporting owner, under the pretext of "improving his breed"; or the extra 
exertion of starting an inordinately heavy load; or an effort to recover 
his balance from a misstep; or slipping upon an icy surface, or sliding 
with worn shoes upon a bad pavement, and other kindred causes. And 
we can repeat here what we have before said concerning bones, in respect 
to heredity as a cause. From our own experience we know of equine 
families in which this condition has been transmitted from generation to 
generation, and animals otherwise of excellent conformation rendered 
valueless by the misfortune of a congenital spavin. 
Symptoms. — The evil is one of the most serious character for other 
reasons, among which may be specified the slowness of its development 
and the insidiousness of its growth. Certain indefinite phenomena and 
alarming changes and incidents furhish usually the only portents of 
approaching trouble. Among these signs may be mentioned a peculiar 
posture assumed by the patient while at rest, and becoming at length so 
habitual that it can not fail to suggest the action of some hidden dis- 
order. The posture is due to the action of the adductor muscles, the 
lower part of the leg being carried inward, and the heel of the shoe 
resting on the toe of the opposite foot. Then an unwillingness may be 
noticed in the animal to move from one side of the stall to the other. When 
driven he will travel, but stifly, and with a sort of sidelong gait between 
the shafts, and after finishing his task and resting again in his stall will 
