332 DISEASES OF THE FEET. 



fail, neurotomy. The French operation of removing the deposits 

 by excision has not found much favour in this country, nor do 

 I think it likely that it will do so, as the incurability of the 

 lameness is generally due to other structures besides the lateral 

 cartilages being involved in the diseased process. An examina- 

 tion of Fig. 5 in Photo-lithograph, Plate III., will illustrate 

 this, and throw a light upon the circumstance that side-bones 

 are occasionally the cause of incurable lameness. 



Neurotomy is very successful in removing this form of lame- 

 ness, and is attended with more permanently beneficial results 

 than when performed for navicular disease. 



It will be useful to bear in mind that when these cartilages 

 are ossified, the horse's gait will lose that elasticity which is 

 so essential to good action. In the cart-horse this is not of 

 much consequence, but in the horse required for other paces 

 than the walk, it is of the greatest importance, not only as a 

 question of soundness or unsoundness, but of the usefulness of 

 the horse and safety of the rider or driver. 



III. — NAVICULAR DISEASE. 



This is the most fertile cause of lameness that we know of 

 in the better-bred horse — the bane of horse-flesh. At one time 

 all cases of obscure lameness in the fore extremity were attri- 

 buted to the shoulder ; but after the discovery of James Turner, 

 all were said to arise from navicular-joint disease. 



Should the student desire the history of this disease, he will 

 find it treated very fully by Percivall in his book on Lame- 

 ness (1849). It was called navicular arthritis (Percivall), and 

 podotrocholitis (Brauel) ; and has been ascribed to various con- 

 ditions, such as contraction of the foot (Coleman) ; laceration 

 of the fibres of the perforans tendon, as it passes under the 

 navicular bone (Dick) ; inflammation of the synovial membrane 

 (Turner, Percivall, and others) ; inflammation of the synovial 

 membrane only, or of that and the navicular bone (Brauel) ; 

 and inflammation, having its origin in the interior of the navi- 

 cular bone, leading to exostoses on or caries of the inferior 

 articulating surface, with degeneration of the fibres of the tendon 

 (Broad of Bath), and its causes to a variety of circumstances, 

 as best suited the whim and fancy of the theorist ; such as 



