198 THE DISEASES OF THE HORSE. 



hock, caused by disease of the tendon of the flexor pedis 

 perforans muscle, which muscle is inclosed in a synovial 

 sheath on the inner side of the ' os calcis/ or by dropsy 

 of the sheath itself, without disease of the tendon. The 

 fluid which fills it may, by pressure, be forced from one 

 side to the other. Hence the name thorough-pin (through 

 and through). This may be described as true thorough- 

 pin, in contradistinction to that associated with very large 

 bog spavins. Thorough-pin is peculiar to short, fleshy, 

 upright hocks. 



Fig. 75. Spring Truss for Thorough-pin and Bog Spavin. 



Remedy. — Eest; high heeled shoe; flannel bandages. 

 Equable pressure from a spring truss. Blister if swelling 

 persists. Open sac at most dependent part if necessary. 



THOROUGH-PIN OF THE KNEE 



Consists in swelling of the sheath containing the per- 

 foratis and perforans tendons, at the back and a little 

 above the knee joint, and is treated similarly to thorough- 

 pin of the hock. 



SPLINT 



Is a bony tumor (exostosis), usually, when on the fore 

 feet, on the inner surface of the metatarsal or metacar- 

 pal bones. Splint of the hind feet, however, is usually 

 on the outer surface of the metatarsal bone. It seldom 

 causes lameness in the hind feet, and does not always 

 cause it in the fore, 



