The Illustrated Horse Doctor / Being an accurate and detailed account of the various diseases to which the equine race are subjected

by Edward Mayhew

The operation of neurotomy is certain relief, but that relief is of uncertain duration. The divided nerve, after a time, reunites. The junction thus formed carries on all the functions of the perfect structure; but a bulb is left behind at the place of union. This bulb is to be easily felt by pressing upon the seat of neurotomy externally with the points of the fingers; and the bulb being felt leads to a knowledge that the horse has been subjected to the operation. Neurotomy, therefore, can never be concealed, if pains are bestowed upon its detection. The operation, however, is not successful in every case.

In some animals, the wound has just closed when junction seems to be formed between the divided ends of the nerve. The lameness then returns as acutely as ever.

In others, the horse will proceed to work, and continue sound ever after—the restored power to use the foot having, in the last case, seemingly destroyed the affection.

Some animals are subjected to operation so late that disease has had time to weaken the pedal structures. The consequence is that no sooner does the absence of feeling tempt the horse to throw his entire weight upon the foot than the navicular bone fractures or the perforans tendon ruptures.

Certain horses, from a tingling sensation in the neurotomized foot—similar to that felt by men in the imaginary fingers of an arm which has been amputated—will stamp violently till they injure it and provoke suppuration; while other feet are so irritable that the head is bent downward and large pieces from the hoof literally bitten off. To account for this last circumstance the reader must remember that, though the foot seems to itch, it in reality has no sensation to preserve it from the teeth of the provoked animal.

Cases occasionally happen of horses having picked up nails, or having incurred wounds in the foot, which, being deprived of feeling, the animal wanted the power to recognize. No lameness was exhibited, and the injury was necessarily unattended to. The foot has been left alone till the hurt has induced mortification.

Weak feet have not been able to endure the consequences of operation. They have sustained no external injury, but the heaviness of tread attendant on a loss of sensation has so battered the senseless member that suppuration has been induced. The hoof has therefore been cast off and the horse been destroyed, although it was discovered in the stable standing with the utmost composure upon the bleeding and exposed flesh.

These are a few of the disagreeables attending a most humane and successful operation. The first requisite for the performance of neurotomy is a sound knowledge of anatomy. A familiar acquaintance with the course of the nerve is essential. It descends in two main branches from the knee, one on either side of the leg. It travels in company with and behind the artery and vein on the inner side of the fore limb. On the outer side it is accompanied by no vessel. About the center of the leg, however, the two nerves are united by a branch which travels over the perforans tendon, connecting the sentient fibers of either side. It is therefore essential, in the performance of neurotomy, to make the primary incision rather low down, especially if it is meant that the high operation should be accomplished, or that all sensation should be destroyed on one side by a single division.

At the pastern the nerve divides; the posterior branch runs direct to the frog. The anterior branch travels in front of the artery for some distance, when it takes a more forward course, dividing into several separate branches.