244 



VETERINARY STUDIES 



of the bones in the deeper parts; and erosions of the articular 

 cartilages. Bone spavins have a tendency to recover without 

 treatment, although in many cases the period required for 

 natural recovery is very long, extending through a period of 

 years. In other cases recovery can never occur. Recovery 

 when brought about by natural or artificial conditions implies 

 that certain of the tarsal bones have united, a process called 

 anchylosis, i.e., union. Inflamed, sensitive surfaces are then no 

 longer rubbing together as the limbs move. 



Fig. 85.— Spavins. Two Types. (M. E. R.) 



A, metatarsals; 



B, tarsals 



I. Spavin with marked bony enlargement, 

 with enlargement and anchylosis. 



II. Blind spavin. Extensive ulceration of articular surfaces; no en- 

 largement; no anchylosis. 2, os calcis; 3, scaphoid or large cuneiform. 



Many bone spavins doubtless appear as the result of slight 

 injuries in susceptible subjects, particularly those that have a 

 strong hereditary tendency to disease of this kind. 



Symptoms. — These cases come out very lame after hard work, 

 step on the toe, and improve with exercise. They often stand 

 with the foot resting in a peculiar way against the other hind 

 foot. In motion they carry the hock joint with as little move- 

 ment as possible and step on the toe. 



What is known as the hock test is made by holding up the 

 limb, with the hock sharply bent, for several minutes, then the 

 horse is started suddenly. In case of spavin the first few steps 

 are very lame. Old horses without spavin may respond to this 

 test and so lead to error if one is not careful. 



