264 PARTICULAR LAMENESSES. 



In the neighbourhood of copper and iron smelting works, 

 bursal enlargements are due to the impregnation of the animal 

 system with mineral poisonous materials. The poison, finding 

 ingress by means of the atmosphere into the lungs and circula- 

 tion, becomes deposited in and around the articulations, more 

 especially of the knees, and finally produces anchylosis. 



All cases where the tendons are thickened must be looked 

 upon as unsound, since they are tied down by the enveloping 

 thecse and annular ligaments, through which they play; and 

 any thickening of their substance must destroy that facility of 

 motion which is so essential to soundness of action. 



The bursa of the extensor metacarpi magnus sometimes be- 

 comes greatly distended — constituting what is termed " capped 

 knee," — from blows or the entrance of thorns whilst hunting 

 and jumping over thorn fences. These thorns may remain in 

 for years without causing any apparent inconvenience to the 

 animal beyond some swelling. 



When capped knee is first observed it is generally accom- 

 panied by some stiffness and pain, showing that more or less 

 inflammation is present. These symptoms should be combated 

 by purgatives, fomentations, and quietude. After a time all 

 signs of inflammation pass away, leaving a fluctuating swelling. 

 This swelling may either be punctured at once, or its reduction 

 attempted by the application of blisters. Of course, if a thorn 

 can be detected it must be at once removed. Blisters, when 

 sufficiently strong, often cause the reduction of these swellings 

 by producing an exudation of lymph into the distended sac, 

 converting the soft, fluctuating swelling into a hardish, indurated 

 mass, which is gradually removed by absorption. But if blisters 

 — and I prefer the cantharidine one to any other, with mode- 

 rately firm pressure after the soreness of the blister has passed 

 away — have no effect in reducing the swelling, the practitioner 

 need not hesitate to puncture and allow the contained fluid to 

 escape. The puncture should be made at the lowest margin of 

 the swelling, and upon its inner side, by a transverse incision, 

 in order to blemish as little as possible. After the puncture is 

 made and the fluid pressed out, the walls of the sac must be 

 kept in apposition by means of a flannel bandage, rolled round 

 the knee from above downwards, until they become united by 

 the adhesive inflammation. The bandage should not be dis- 



