358 DISEASES OF THE HORSE, 
of symptoms, treatment, etc., are our reasons for treating under 
a single head the ailments we have grouped together in the present 
section. 
Cause-—The great, comprehensive, common cause of, sometimes 
permanent, sometimes only transient, disability of the horse is exter- 
nal traumatism. 
Blows, bruises, hurts by nearly every known form of violence, 
falls, kicks, lacerations, punctures—we may add compulsory speed 
in racing and cruel overloading of draft animals—cover the entire 
ground of causation of the diseases and injuries of the joints now 
receiving our consideration. 
In one case, a working horse making a misstep stumbles, and fall- 
ing on his knees receives a hurt, variously severe, from a mere abra- 
sion of the skin to a laceration, a division of the tegument, a slough, 
mortification, and the escape of the synovial fluid, with or without 
exposure of the bones and their articular cartilages. 
In another case, an animal, from one cause or another, perhaps an 
impatient temper, has formed the habit of striking or pawing his 
manger with his fore feet until inflammation of the knee joint is 
induced, first as a little swelling, diffused, painless; then as a perios- 
titis of the bones of the knee; later as bony deposits, then lameness, 
and finally the implication of the joint, with all the various sequelze 
of chronic inflammation of the knee joint. 
In another case, a horse has received a blow with a fork from a 
careless hostler on or near a joint, or has been kicked by a stable 
companion, with the result of a punctured wound, at first mild- 
looking, painless, apparently without inflammation, and not yet caus- 
ing lameness, but which, in a few hours, or it may be only after a few 
days, becomes excessively painful, grows worse, the entire joint swells, 
presently discharges, and at last a case of suppurative synovitis is 
presented, with perhaps disease of the joint proper, and arthritis as 
a climax. The symptoms of articular injuries vary not only in the 
degrees of the hurt but in the nature of the lesion. 
Or the condition of broken knees, resulting as we have said, may 
have for its starting point a mere abrasion of the skin—a scratch, 
apparently, which disappears without a scar. The injury may, how- 
ever, have been more severe, the blow heavier, the fall aggravated 
by occurring upon an irregular surface, or sharp or rough object, 
with tearing or cutting of the skin, and this laceration may remain. 
A more serious case than the first is now brought to our notice. 
Another time, immediately following the accident, or -possibly as 
a sequel of the traumatism, the tendinous sacs may be opened, with 
the escape of the synovia, or, worse, the tendons which pass in front 
of the knee are torn, the inflammation spreads, the joint and leg 
are swollen, the animal is becoming very lame; synovitis has set in. 
