Williams, Fisher, and Udall: The Spavin Group. 51 
processes in the tendons and other parts. The bones become 
more porous and their power of resistance decreases until they 
crush under pressure, or yield to tension of their tendons or liga- 
ments, the ends of the latter tearing away accompanied by frag- 
ments of the degenerate bone. Or the tendon may so far 
degenerate as to part transversely. 
It is not always the part which was considered chiefly dis- 
eased before operating that gives way after neurotomy, but may 
be| some other bone or tissue. For example, after neurotomy 
for navicular disease, the navicular bone is fairly protected, and 
may escape serious injury while the disease processes in the pedal 
bone, previously ignored, become intensified and the flexor 
tendon tears away from its semilunar crest carrying portions of 
bone with it. Following double neurotomy for spavin the break- 
ing down may occur in the tarsal bones, the sesamoids, the os 
pedis, or the flexor tendons. 
Neurotomy has the futher danger that in the absence of 
sensation, any injury to the part is unheeded, and the highly 
protective office of pain is wanting so that the patient continues 
to use the injured part with disastrous results, preventing the 
healing of the injury, causing it to extend and finally destroying 
the foot. (Fig. XX.) 
The selection of cases for neurotomy requires a high degree 
of judgment. After excluding all badly formed feet and all 
which are suffering from or tending to infections, we still need 
to determine which will bear the new strain put upon them when 
the pain is removed. 
The general rule is that we should not unnerve an animal 
which is acutely or extremely lame, in bad general condition, or 
in a recent case. This rule is in full harmony with our view 
of the constitutional character of the disease and would warrant 
our stating the above rule in a new garb — do not perform neu- 
rotomy so long as the general disease is active, but wait until 
the systemic disturbance has passed and the question has resolved 
itself into a painful, incurable local lesion, the parts retaining 
sufficient vitality to safely resume their normal function when the 
sense of pain is destroyed. 
Opinions of neurotomy will always vary because in different 
localities and among different classes of horses the seriousness 
of the systemic disease will differ. In those areas where the 
disease is generally mild and the active systemic disturbance 
