!8o DISEASES OF THE DOMESTIC ANIMALS 



On the other hand, when the articular surfaces of the tarsal 

 pastern and pedal joints are involved, we have to do with a chronic 

 inflammation beginning in the shaft of the bone near the joint and 

 extending to the articular surfaces of the joint — hence the name 

 osteoarthritis. A destructive and regenerating process go on at 

 the same time. In the bone we have a rarefying (and often con- 

 densing) ostitis; the inflammation extending to the periosteum, 

 there follows a productive inflammation of new bone about the 

 joint, deforming it (hence the deformans), and ultimately leading 

 to external anchylosis. In the meanwhile the articular cartilage 

 degenerates and becomes eroded, while in other places prolifera- 

 tion of bone and internal anchylosis of the joint are apt to result. 

 Ringbone, invading either the fetlock, pastern or pedal joints, rep- 

 resents the same processes. 



Ringbone and spavin, then (when not involving the articular 

 surfaces), together with splint, are properly described under the 

 name Chronic Ossifying Periostitis. Ringbone and spavin (when 

 involving the articular surfaces) are correctly classified as Chronic 

 Osteoarthritis Deformans. 



Spavin.— The symptoms of spavin, as lameness and stiffness, 

 with sometimes sudden flexion (like stringhalt), and tumor on the 

 inner surface of the hock, are well known. Sometimes when tumor 

 is absent, in so-called occult spavin, diagnosis must be made by ex- 

 clusion. Local heat and inflammatory signs are occasionally seen. 



Treatment. — The treatment of spavin is successful in relieving 

 lameness in over 50 per cent, of cases, especially in young animals. 

 Firing the internal face of the hock in 15 to 20 points and the im- 

 mediate application of a cantharidal ointment (1 to 8) constitute 

 the most successful treatment when followed by a rest in the stable 

 of six weeks. Cunean tenotomy, done over the seat of the spavin 

 and followed by firing and blistering, is sometimes successful when 

 the latter treatment has failed. Periosteotomy has been followed 

 by good results. A transverse incision is made across the middle of 



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