ON THE NAVICULAR DISEASE. 13 



niencement, is neither more nor less than a bruise of 

 the synovial membrane lining the joint. 



Although it appears that some degree of violence 

 is essential to the completion of this formidable dis- 

 ease, yet I am convinced that it does not originate 

 in wear and tear, from contact with either the roads onvinatos not 

 of the former or present day : it has, in reality, its ^ea"' ami tear 



... , f^ • ,"• 1 ] J •* +1 as from rest. 



orio-m m rest. It is certamlv enoenuerea m the 

 stable, but becomes permanently established by 

 sudden violence out of the stable : and I have fre- 

 quently observed, that, under peculiar pre-existent 

 circumstances, a very moderate proportion of exer- 

 tion on a hard road or stones has been quite suffi- 

 cient. Two or three severe days' work in succes- 

 sion, immediately after long continued confinement 

 in a stall, and the hurried pace and distance united, 

 would compel the animal eventually (though per- 

 haps reluctantly) to convey his weight abruptly, and 

 with considerable force, on this obstructing body 

 formed by a fixed elevation of the frog in conjunc- 

 tion with a morbidly thick sole. 



I believe Mr. Coleman is of opinion, that a de- 

 fective secretion of synovia is the first derangement 

 of the navicular joint : this I take to be merely se- 

 condary, and for this reason, that I have uniformly 

 found the navicular joint sound, and containing the 

 due proportion of synovia in feet, however much 

 contracted, which had always been known to have 

 been free from lameness. The bruise and conse- 



