NAVICULAR DISEASE. 
21 
This liability to change on the part of the hoof in its size, shape 
and quality , has a most important bearing on the organization , 
not merely of itself \ but also of the structures contained within 
it, and on different parts of the limbs as well ; indeed, the whole 
conformation of the animal is changed by acquired conditions 
of this wonderful “ buffer,” so unlike the foot of every other 
species of animal, that it must be the part primarily affected , 
the part that predisposes to and determines the character of 
such diseases, and the part that must be first treated, if the 
cause is to be philosophically studied, and successfully re¬ 
moved or overcome. For with an integument as soft and 
pliable as the skin, instead of the “ horny box,” it must be im¬ 
possible to produce navicular disease, bone spavin, and many 
other diseases and defects with histories such as theirs, which 
we are now familiar with; just as there must be many dis¬ 
eases peculiar to horses’ limbs that could not occur on the 
limbs of other species than solipeds. 
Let us now suppose a horse having received a severe blow 
with a club at the seat of ordinary bone spavin, or that his 
mate has kicked him there, and a bony growth or deformity 
results, somewhat similar, perhaps, to true bone spavin. It 
could hardly be regarded as good pathology to either name, 
or similarly classify, diseases having such dissimilar histories 
and causes, any more than it would be to regard degenera¬ 
tion of the navicular bone, as met with in true navicular 
diseases, as the same disease of the same bone, the result of 
inflammation from a nail having accidentally or otherwise 
penetrated it. 
In comparative work of this kind, clean lines must be 
drawn to give the student an exact, logical and intelligent 
appreciation of the subject. It must not be forgotten that 
while the hoof is liable to be affected adversely by heat or 
cold, moisture or drought, tear and wear, or idleness, etc.—ex¬ 
trinsic and intrinsic influences—it is possible to guide its 
growth in a right or wrong direction, and it can be cultivated 
with as much success as the gardener acquires in guiding and 
training his bulbs and rare plants. 
In practice we often meet with cases of navicular disease, 
