ANIMAL PATHOLOGY. 
480 
which the operation was performed, had the stronger and firmer 
crust of the two. These cases speak much for the permanent effect 
of the division of the plantar nerve when well performed, and in 
navicular disease. If you determine to operate on the plantar 
nerve, take care, like poor Castley, that your work “ is done, when 
it is done/’ Excise, like him, a sufficient portion of the nerve, to 
prevent all communication by means of the anastomosing branches, 
so numerous here ; and, like him, if you operate for neurotomy, 
operate early, before the inflammation has rendered the navicular 
bone carious, or the friction between its roughened surface and 
the tendon has so worn down the latter, that it gives way as 
soon as the horse gets up. While the poor animal is in pain, he 
takes care to render his extensor muscles in a manner subservient 
to the flexors, and the weakened, attenuated cord is not 
broken through ; but when, put off his guard by the sudden 
disappearance of pain, he gives to the antagonist sets their 
natural play, and throws on the tendon its natural weight, it 
is ruptured in a moment, and the pastern is letdown, and the 
horse is ruined for ever. This will guard you as to the time 
when alone you will apply neurotomy as a cure for the navicular 
disease, namely, in comparatively recent cases. You also per- 
ceive here another illustration of that beautiful mysterious 
adaptation of muscular power and consent of muscular action, 
which have been too much unobserved and disregarded. 
The Operation resumed. — Well, gentlemen, you have 
determined where you will operate, and you have shaved away 
the hair close from that part. You will loosen the leg to be 
operated upon from the hobbles, still securing it in the usual 
way, and placing under it a truss of hay in order con- 
veniently to elevate it. I will suppose that you are operating 
above the fetlock. Immediately above it, and at the edge of the 
great metacarpal bone, and between it and the flexor tendons, 
you will plainly feel two cords, and, somewhat indistinctly, a 
third. That nearest to the bone you will recognise by its pulsa- 
tion to be the metacarpal artery ; that nearest to the tendons, a 
rounded and more yielding cord, is the metacarpal vein ; and, 
between them, and distinguished by its hardness, is the meta- 
carpal nerve. Following the line which it pursues, you will 
make your incision with your scalpel, fairly through the integu- 
ment, and almost down on the nerve — the incision being a 
little less than two inches in length, and having as its termina- 
tion the beginning of the swelling of the fetlock joint. You will 
then readily dissect away the intervening cellular substance, and 
the three cords will be exposed to view, lying in the relative 
situations which I have described. I would urge the young 
practitioner always to use the tourniquet, for there will then be 
