ULCERATIVE DISEASE OF JOINTS. 47 



especial degree to experience the effects of stress of work and con- 

 cussion. The navicular joint, totally unable of itself to bear the im- 

 press of weight of the body, is constructed upon that spring-like con- 

 trivance that enables it to play up and down — descend and ascend 

 — according as the weight presses hard upon it or not : its spring 

 constitutes its defence against concussion ; and any thing that checks, 

 arrests, or interferes with the action of that spring, subjects it to 

 injury, to bruise, to breach, even to fracture. Again, in regard to 

 the hock, that is the identical joint through whose operation the 

 grand work of progression is carried on : no wonder, therefore, 

 that it should prove out of order oftener than any other of the hind 

 joints, or that we should so often discover ulceration in it. Both in 

 the navicular and hock joints, therefore, have we great cause to look 

 for that which is likely to injure the synovial membrane, or at all 

 events excite inflammation in it. The question is, is the ulceration 

 a consequence of inflammation, or does the inflammation follow the 

 ulcerative disease 1 



A fact that appears to us to throw much light upon this question 

 is that of articular lameness in many instances manifesting itself 

 ''all of a sudden." A horse, never lame perhaps in his life, shall 

 leave the stable in his ordinary state of perfect soundness, and 

 while out drop suddenly lame, and from that moment become and 

 continue a lame horse, without there being to the observation of his 

 master anything whatever to account for his lameness. Can such 

 a lameness as this — known from experience commonly to prove 

 articular — arise from inflammation] Can inflammatory action have 

 set in all of a sudden 1 What, then, seems the feasible way of 

 accounting for his lameness, assuming it to be in the joint, most 

 likely either the navicular or hock ] Why, that bruise or breach 

 or solution of continuity of the synovial membrane has taken place, 

 and that this is followed by ulceration and by inflammation. If 

 the horse be examined immediately after lameness has befallen 

 him, the suspected joint or foot will feel cool — as free at least from 

 any extraordinary heat as the fellow one in the opposite fore or 

 hind leg : four-and-twenty or eight-and-forty hours afterwards, 

 however, heat becomes detectible, inflammation has set in, and all 

 doubt as to the locality of the seat of lameness is dispelled. 



