208 DISEASES OF THE FEET. 



is usually hard. We may easily understand that the effect of this 

 continued standing on a cold surface which is a good conductor of 

 heat, is to lower the vitality of the living structures of the feet, 

 and to predispose them to become injuriously affected by subse- 

 quent concussion. In India, on the contrary, where troop horses 

 are accustomed to stand on earth, and not on stone, and where the 

 ground is much warmer, navicular disease is far more rare. Cab 

 horses, which are particularly liable to this malady, have, as a rule, 

 to do all their standing, when outside, on stone, or on metalled 

 roads. These facts suggest the advisability of providing, when 

 practicable, a bad conductor of heat, such as wood, .for horses to 

 stand on, instead of stone, as, for instance, on cab-ranks. 



Although long-continued standing is very apt to produce lami- 

 nitis, it does not seem capable, of itself, to give rise to navicular 

 disease; whether the animal stands on a bad conductor of heat, 

 as he usually does on board ship ; or on a good one, like wet soil, 

 as is often the case with farm horses. 



3. Trotting. I am strongly inclined to think that giving a 

 horse his work — supposing it to be severe or ill-arranged, and 

 the ground hard — at the trot, predisposes him to navicular dis- 

 ease; because the animals which most frequently contract this 

 disease, do their work at that pace. 



An upright and concave form of foot, with strong heels, is 

 usually supposed to be conducive to navicular disease. As this 

 conclusion has, I think, been arrived at in most cases, after 

 the complaint has become fully manifest, and as the peculiar gait 

 of navicular disease induces the shape which in popular opinion 

 confers liability to this ailment; I do not think this supposition 

 can be accepted without further proof. 



ALLEGED CAUSES. — Those usually advanced by veterinary 

 authorities are: 1. Concussion. 2. Sprain of that portion of the 

 perforans tendon which passes over the navicular bone (Dick). 

 3. The employment of high heels or calkins (Williams). 4. Com- 

 pression, ''' through the weight of the body on one side, and the 

 pressure of the perforans tendon on the other " [Fred Smith). 

 5. Rheumatism. 6. Heredity. 7. Direct injury from stones, 

 nails, etc., " picked up " by the feet. 



1. Concussion. When we have to decide between the respec- 

 tive claims of a number of alleged causes of a disease, it is but 

 reasonable to give priority to the one which is found, most 

 commonly, to affect the sufferers. Harness horses which are 

 used for quick road work, are, above all other classes, peculiarly 

 subject to this disease; and owing to the nature of their labour, 

 are proportionately exposed to the ill effects of concussion on 



