NAVICULAR DISEASE. 
637 
adduced against this view, but further investigations can alone determine 
to what extent such peculiarities act as causes of the disease. One 
argument against it is, that the disease almost invariably occurs in 
well-bred horses, especially in those with narrow, high feet. In coarsely- 
bred animals it is only seen exceptionally, and under very special 
circumstances. 
Only two cases are reported of the disease also affecting the hind 
feet. In both cases the investigators (Wrainsford and Fambach) con¬ 
firmed their diagnosis by post-mortem examination, and there is no 
doubt that chronic inflammation of the gliding surface of the navicular 
bone and of the perforans tendon had occurred, but no explanation of 
the cause is given. In Fambach’s case the horse was lame for nine 
months; as much as possible it avoided placing weight on the limb, and 
both during movement and at rest kept the limb flexed. 
The almost constant occurrence of navicular disease in the flexor 
apparatus of the fore limb and in the bursa podotrochlearis is partly 
due to the greater weight borne by the front feet and to the violent 
strains thrown on the flexor tendons during rapid movement on hard 
ground or under the weight of the rider. Under these circumstances 
the navicular bone is exposed to severe pressure on the one side from 
the coronet bone, on the other from the flexor'tendon; and though 
disease of the joint is seldom caused by bruises from below when 
moving over uneven ground, yet such an accident is conceivable. It is 
still very doubtful how strains, &c., act in producing the disease. The 
variety of opinion on this point is to some extent due to confusing 
cause and effect. In no lameness are errors of diagnosis so common as 
in navicular disease. 
The older English authors considered that a small, narrow condition 
of the hoof often caused this disease, the strongly arched sole pressing- 
on the navicular bone. This view is due to confusing navicular disease 
with contracted sole, as Brauell has pointed out. Williams regards the 
upright position of the fetlock as a predisposing factor, a view which is 
pertinent, so far as the position of the fetlock is in some degree referable 
to that of the hoof. 
Peters and Fambach first explained the connection between this 
conformation and the disease. Excessive lowering of the heels causes 
the axis of the hoof to become more oblique than that of the pedal 
bone, and throws excessive strain on the flexor perforans at every 
movement. The pressure on the navicular bone thus produced is 
increased by the flexor tendon describing a sharper curve in its passage 
over the navicular bone. 
Leaving the toe too long may similarly cause the disease, or induce 
inflammation of the flexor tendons. The upright position of the pastern 
