ON THE CAUSES OF DISEASE. 23 
ties is usually the principal seat of the disease. The animal sud- 
denly becomes lame; the inguinal and other glands in the groin 
become enlarged and very painful, and the swelling and pain 
gradually extend downward along the course of the absorbents, 
while the limb becomes a great deal larger than its natural size, 
There is, at the same time, a good deal of constitutional fever, 
with a full and bounding pulse. The swelling of the leg is, in 
the first instance, inflammatory, being hot and tender, and the 
skin, over the part affected, hard and tense. Such swellings may, 
by judicious treatment, be removed; but, in cases of a chronic 
character, or where the same limb has been previously affected, 
iymph is effused, forming hard and nodulous, and even diffuse 
swellings, which often cause lameness, by interfering with the mo- 
tions of the joints or tendons. These indurated swellings must 
be carefully distinguished from the serous effusions above noticed, 
which, although giving the animal an unsightly appearance, do 
not materially impair his usefulness. 
“ Grease consists in a morbid condition of the sebaceous glands 
of the horse’s heels and fetlocks. It occurs in various degrees of 
intensity ; sometimes as a mere scurfy itchiness of the skin about 
the fetlocks, more commonly of the hind extremities; sometimes 
attended with much inflammation, causing great heat, pain, and 
swelling, and an ichorous fetid discharge; sometimes causing fall- 
ing off of the hair about the heels, and the formation of deep 
cracks and fissures; and sometimes becoming so violent and in- 
veterate as to cause eversion of the sebaceous glands, formation 
of granulations, and secretion of pus, constituting the loathsome 
complaint termed the grapes. There are few diseases better de- 
serving the epithet of hereditary than grease, and few in which 
the hereditary nature can be more easily discovered and traced. 
Almost every practitioner can bring to his recollection cases show- 
ing the tendenvy of this disease to descend from parent to off- 
spring. A friend of mine, some years ago, purchased a valuable 
four-year old entire horse, adapted for agricultural purposes. 
When bought, he appeared perfectly sound, and his limbs were 
nearly black, well-formed, and fine; within a short time, how- 
ever, they became thick and greasy. And, although the mares 
to which he was put were perfectly free from such faults, the prog- 
eny have shown, in every case where they can be traced, unmis- 
evidence of their inheriting the greasy diathesis of their 
