157 



exertion. Or, the swelling extends along the inner 

 surface of the hock, oblong, a little broader above 

 than below, bony, sometimes involving the entire 

 joint, and occasioning more or less limping. Or, a 

 soft round swelling over the whole internal surface 

 of the hock, at first not impeding the horse's gait, 

 but afterward becoming indurated and causing a 

 rigidity of the hock and consequent lameness. Or, a 

 hard osseous swelling at the upper and inner side 

 of the femur, causing a lameness depending upon 

 the extent to which the ligaments of the joints are 

 involved. Or the muscles of the hind-quarters are 

 not visibly affected, the horse does not limp, but 

 simply raises one or both the hind limbs (for one is 

 seldom affected alone) unnaturally high, with a 

 spring, and puts them down again with a spasmodic 

 twitching movement." (Spring-halt.) 



At first the animal seems afraid to use one, or the 

 other of the hind-legs, and a little lameness is no- 

 ticed on first starting off. Afterward when return- 

 ing to the stable after exertion, the horse stands on 

 the toe of the affected limb, and limps considerably 

 on turning around and first commencing to walk ; 

 after moving a little, the lameness disappears, and 

 only returns again after he has been standing some 

 time. This will soon be followed by swelling. 



CAUSES. There is a predisposition to this affec- 

 tion in some families of horses, and when this pre- 

 disposition exists, strains, violent exertion, over-work, 

 a blow or other injury, readily develops the spavin. 



