286 DISEASES OF THE HORSE. 



with an additional quantity of synovia, which, pressing against 

 the capsular ligament, distends it, as we may perceive in bog 

 spavins. As this usually takes place in a gradual manner, it 

 seldom occasions lameness, or, if it does, it is of a temporary 

 nature. The enlargement, however, continues as long as there 

 is sufficient synovia to distend the capsule ; if we blister the part 

 and keep the horse on poor diet, it disappears for a time, there 

 being then less synovia secreted : it returns, however, with work 

 and good living. In old horses, it often disappears altogether, 

 in consequence of the diminished amount of synovia secreted. 



Such being the nature of this disease, the plan of opening it 

 to let out the contained fluid is very injudicious, for we run the 

 risk of creating dreadful inflammation by exposing so important 

 a cavity. If it has been sometimes done with impunity, it is 

 because the opening has been so small as to close up very soon, 

 and before much irritation has been produced. A cure must not 

 be expected unless we can cause adhesion to take place between 

 those pai'ts that have given way ; and this can only be done, if 

 at all, in the early stages, either by pressure on the part or by 

 perfect rest, which can best be effected by the application of a 

 blister. 



Blood spavin is a fanciful disease, and therefore requires no 

 further notice. — Ed.] 



[ Thorough-Pins 



Are similar in their nature to bog spavins. There are two 

 situations in which they are found ; one rather above the point 

 of the hock, and the other below it. In each case they appear 

 both outside and inside ; and their contents may be pressed 

 from one to the other, from which circumstance they derive 

 their name. The upper thorough-pin appears to be the enlarge- 

 ment of the capsular bag in which one tendon moves upon an- 

 other — the tendo Achillis and the perforatus; and the lower 

 one a distension of the capsular ligament of the hock joint itself, 

 at its upper and back part, and behind the tibia. Thorough- 

 pins and bog spavins often exist together, and then the fluid can 

 be pressed from one to the other, though not readily. 



Thorougli-pins are more rarely the cause of lameness than 

 even bog spavins, I have, however, known a troublesome and 

 obstinate lameness produced from the upper thorough-pin, or 

 perhaps rather from some strain of the tendon which attended it. 

 It gave way, however, at length, to a seton placed over the part, 

 — not through it. I have also succeeded in removing a very 

 large thorough-pin in the lower situation, by the long continued 

 application of equal parts of iodine, and mercurial ointment, pre- 

 viously, however, stimulating the part with a mild liquid blister. 



