DISEASES OF THE HIND LIMB 



181 



sometimes advisable to repeat the counterirritatioii if the results 

 of the first firing are unsatisfactory. 



Bog Spavin. — Bog spavin is an extensive distention of the 

 capular ligament of the hock-joint by synovia (Fig. 48). It is 

 geuerallv due to chronic inflammation of the synovial membrane. 

 This blemish or unsoundness 

 is most common in young 

 horses. Thorough pin (Fig. 

 49) involves the sheath of the 

 large tendon only. (Com- 

 pare Figs. 48 and 49.) 



Certain conformations of 

 the hock favor the develop- 

 ment of bog spavin. This is 

 especially true of upright and 

 " fleshy " hocks. Hard work 

 may cause the hocks to " fill " 

 when followed by a brief 

 period of rest. The common 

 cause is a sprain due to slip- 

 ping and pulling heavy loads. 



The following symptoms 

 may be noted : Lameness is 

 not a common symptom of bog 

 spavin. If there is inflamma- 

 tion present or the articula- 

 tion is injured, lameness oc- 

 curs. The soft swelling that 

 characterizes the bog spavin 

 is most prominent toward the inside and front of the region. In 

 the upper portion or hollow of the hock, and on the inside and out- 

 side, there may be a second enlargement. Smaller enlargements 

 may be present in other regions. All of the swellings feel soft, and 

 pressure on any one of them moves the fluid present in the others. 



Fig. 49. — Thorough pin. Note the relation 

 of the enlargement to the tendon, and the free- 

 dom of the hocks from bog spavin. 



