avicular
disease is seen as a result.

In conclusion, it is well, perhaps, to say that, no matter to which
particular theory of causation we may lean, we should make up our minds to
consider them as a whole. While one cause may be exciting, the other may
be predisposing, and the two must act together before evil results are
noticed. It may be that even more than two are concerned in bringing on the
disease, and to each the careful veterinarian will give due consideration.

_Symptoms and Diagnosis_.--In the early stages of navicular disease the
symptoms are obscure. Pointing of the affected limb is the first evidence
the animal gives. This, however, more often than not, goes unnoticed,
and the first symptom usually observed by the owner or attendant is the
lameness. Even this is such as to at first occasion no alarm, being
intermittent and slight, and only very gradually becoming marked. In a few
cases, however, lameness will come on suddenly, and is excessive from the
commencement. It is the lameness, slow in its onset, intermittent in
its character, and gradual in its progress, however, that is ordinarily
characteristic of navicular disease.

The animal is taken out from the stable sound, with just a vague suspicion,
perhaps, that he moved a bit stiffly. While out he is thought by his driver
or rider to be going feelingly with one foot or with both. Even this is not
marked, and the driver has some difficulty in assuring himself whether or
no he really observed it, or whether it was but imagination.

On the return home the limb is examined, and nothing abnormal is to be
found. The leg is of its normal appearance, and neither heat nor tenderness
is to be observed in it or in the foot. On the following day the animal
again is sound, and the lameness of the previous day is put down to a
slight strain or something equally simple. The patient is then, perhaps,
rested for a day or two. When next he is worked he again moves out from the
stable sound, but again during the going gives the driver the unpleasant
impression that something is amiss; and so the case goes on. One day the
owner fears the animal is becoming seriously enough affected to warrant him
in calling in his veterinary surgeon; the next he is confidently assuring
himself that nothing is wrong.

Perhaps the animal is now rested for a week or two, or even for a month or
two, hoping that this will put him sound. Immediately on commencing work,
however, the same