DISEASES OF THE HIND LIMB 177 



sudden, purposeless flexion of the hock-joint (Fig. 45). Horses 

 that are slightly affected may show this movement of the hind 

 limbs when first exercised. Other horses may be " string-halted " 

 when backed, turned, walked, or trotted, and fail to drive out of 

 it. The cause of true " string-halt " is not known. 



The treatment recommended is surgical. This consists in 



Fig. 45.— String-halt. 



cutting the tendon of the peroneus muscle. The seat of the 

 operation is a little below the hock and on the external face of 

 the cannon. 



Spavin. — A spavin is a chronic inflammation of the articular 

 faces of the hock bones, ligaments and synovial membranes. The 

 inflammation may result in the formation of a bony enlargement 

 on the inner surface of the region, and a union between the small 

 bones forming the lower portion of the hock^ and the upper 

 extremities of cannon and lower hbck bones. 

 12 



