334 THE PRACTICE OF VETERINARY MEDICINE. 



the disease being most frequently met with in those horses 

 having short upright pasterns and a pounding action. The 

 horses least predisposed to the disease are those with 

 oblique pasterns, the weight in such animals being removed 

 from the coffin-joint. But even in such a case the natural 

 protection afforded by a faultless conformation can be — and 

 frequently is — set at naught by shoeing with high-heeled 

 .,v shoes, by means of which the articulation is straightened 

 D, weight is thrown upon the coffin-joint, and the navicu- 

 lar bone now becomes exposed to injury by concussion. 

 The disease is often caused by allowing a horse to remain 

 idle for a few days, feeding him highly in the meantime, 

 then taking him out and giving him a severe drive or ride 

 on a hard road, and more especially if the animal is pre- 

 disposed on account of faulty conformation, or is improperly 

 shod, etc. It is of most frequent occurrence amongst horses 

 used upon hard roads, as saddle and carriage horses, 

 and sometimes trotting horses and racehorses on the 

 American continent, as they usually race on hard tracks. 

 It is rarely seen in racehorses in Great Britain, as they are 

 properly shod, and, although doing fast work, it is on the 

 grass or turf, and soft ground. Direct injury to the per- 

 forans tendon, as by a punctured wound, may also be 

 mentioned as a cause of navicular disease, and it is also said 

 to be due in some cases to a rheumatoid diathesis. Navicu- 

 lar disease occurring in a hind-foot is very rare, the disease 

 being principally met with in the fore-feet, usually one foot 

 only being affected, sometimes, however, both fore-feet 

 become affected ; in some cases simultaneously, but most 

 frequently one at a time. Navicular disease in all its various 

 stages constitutes unsoundness, and as it may in some cases 

 exist for months before any actual lameness appears, the 

 practitioner cannot be too careful in his examinations as 

 to soundness ; hence any undue heat or tenderness, contrac- 



