126 THE SUMMERING OF HUNTERS. 



The diseases of the lubricating apparatus are for 

 the most part all one disease, going by different 

 names according to the part of the lubricating appa- 

 ratus affected. It becomes affected by having more 

 to do than it can bear. The extra work stimulates 

 the surfaces which produce the oil, and being con- 

 stantly^ overstimulated they pour out more oil than 

 in health, and their sub-surfaces become thickened 

 and hardened. Oil or synovia is poured out by 

 these surfaces, and after being used a little is ab- 

 sorbed again by them — the old oil is changed for 

 fresh oil. This is in the healthy state. In the 

 overworked state the oil is thrown out but not again 

 absorbed, at least not at the same rate as it is thrown 

 out ; then we have two conditions as a result : — 



1. The parts become distended (thorough pin, 

 wiudgall, &c.), and the old oil undergoes change ; 

 the most observable change is that of being more 

 thick and solid, and, of course, less useful as oil. 

 With these lubricating surfaces there are two well- 

 marked stages of the disorder we have endeavoured to 

 define. The first stage is that in which the parts being 

 overworked return to their natural state with a 

 night's rest. This is well seen in the forelegs. 

 Perhaps a horse comes in with his back tendons hot 

 and swollen, and a night's, rest, with or without cold 

 wet bandages, "fetches them down." The other 

 stage is what we may call the permanently enlarged 

 state. Here the horse always, and under all circum- 

 stancesj has a " thorough-pin" or a " windgall." It 



