Neurectomy for Navicular

Many people have heard of "nerving" a horse for navicular disease, as was mentioned in the Step-by-Step column in the August issue of The Horse. But did you know that the nerves in that heel area can grow and eventually allow the horse again to feel pain? This innervation or regrowing of the nerves is the norm rather than the exception with a neurectomy. According to equine surgeon John Madison, VMD, Diplomate ACVS, a neurectomy always should be considered a temporary procedure.


Anne M. Eberhardt

"You usually get one year of pain-free use of the horse on average," said Madison, who owns Ocala Equine Hospital in Florida. "Sometimes you get more time, sometimes less time."

A neurectomy involves cutting both palmar digital nerves below the base of the sesamoid, said Madison. "You don't want to lose sensation in the entire foot, so you don't go above that point," he noted.

Madison said there are several methods of severing the nerves, with no research that shows one technique better than the other. He prefers the capping technique, considered a temporary procedure, which involves cutting the nerves with a sharp knife and then capping the ends of the nerves by taking the epineurium (tissue around the outside of the nerve) and making a cap over the end of the nerve.

Capping is done in an effort to decrease the incidence of neuromas. A neuroma is a disorganized mass of nerve tissue that occurs at the upper end of the nerve stump. It is thought that capping the nerves slows the growth of new nerve fibers.

"They can be exquisitely painful in people and horses," said Madison.

A neurectomy also can be done by freezing, or using a CO2 laser.

There are many considerations to be pondered before deciding on a neurectomy. Who owns/rides the horse and its intended use are the two most important. The horse must block with a posterior digital nerve block or the neurectomy is worthless, he added. Also, the horse has to have a chronic lameness originating from the heel that is not responsive to shoeing, butazolidin, or isoxsuprene, or has responded some but not enough for the horse's intended use.

While Madison said he would not hesitate to nerve a horse which had an experienced owner/rider, he would be hesitant to perform the surgery on a "school" horse or a horse with an inexperienced rider because of the possible side effect of the horse stumbling.

"If the owner is experienced and is aware of the side effects, I don't have any problem doing a neurectomy," he said.

Madison added that he has seen stumbling as a problem only in about 30% of the horses he has observed with neurectomies. The stumbling, he feels, probably has more to do with the underlying cause that necessitated the neurectomy than as a result of the surgery.

Another possible side effect of the surgery is a ruptured deep flexor tendon. This can occur especially if the tendon was torn or worn before the surgery.

"It isn't fatal, but it is career-ending," said Madison.

When a horse is nerved, the owner must pay careful attention to the bottom of the foot, because the horse cannot feel a bruise, abscess, or foreign object imbedded in the nerved region, which takes in from the front of the frog back to the heel area. He stressed that the foot should be carefully cleaned and looked at each day to avoid secondary problems.

While untenable pain due to navicular syndrome and caudal heel syndrome is the most common cause of performance horses' being nerved, Madison said in Thoroughbred racehorses a wing fracture of the coffin bone often necessitates a neurectomy.

The surgery can be performed two or three times on the same horse. At some point, however, the neurectomy has been done high enough that it starts to take away feeling in the entire foot. There also is the potential problem of scarring around the nerves affecting blood supply to that digit. A neurectomy can be done in a standing, sedated horse, but most of the time the surgery requires general anesthesia, which can be costly and adds another element of danger to the procedure.

Case In Point

Johanna Reimer's horse Kye has undergone his third, and final, neurectomy. Reimer, a board certified veterinarian with the Rood and Riddle Equine Hospital in Lexington, Ky., knows from firsthand experience that a neurectomy is not a lasting procedure.

"But with Kye, we got three functional years of doing what he enjoyed," said Reimer. "His attitude improved when the pain was removed after each neurectomy."

Kye was one of those horses who always was easy to get foot sore, and often was sore after being shod. His feet would improve, then get worse again. After various farriers and shoeing techniques, he finally improved. With his new farrier, he always seemed to be slightly sounder for about 10 days after shoeing, then would be sore again. Bar shoes of various types and other shoeing techniques were tried, but nothing seemed to work or last long. Reimer thought going barefoot might help the horse, and he was good for about a month with no shoes, then came in very lame. He got to where he had no response to Bute or isoxuprine, and would block with a palmar digital nerve block. Kye would stumble often because his foot hurt. As a result of the pain, his stride would be short and choppy because he wouldn't lift his foot as high so that when it again was placed on the ground, there was less concussion.

The series of X rays showed changes in the navicular bone and surrounding area characteristic of navicular syndrome. The decision was made to do a neurectomy.

Kye was shod carefully and Reimer made sure the foot was not sore or quicked prior to having the neurectomy surgery.

"He was able to go back to competition at first level horse trials," she said. "He never stumbled, and he was in complete control."

Unfortunately, after about six to eight months, he began to show the same signs of lameness as before the neurectomy. An examination, including a posterior digital nerve block, proved that it indeed again was the navicular area causing the pain.

"He was capped the first time, and the capping was still in place, but the area had reinnervated," said Reimer.

The neurectomy was performed again, and this time, Kye was sound for about 2 1/2 years.

"He has arthritis in both coffin joints that comes with the disease, so I had to make sure not to work him on hard ground," noted Reimer. "He did great, and competed sound. Then he started with the toe pointing and the whole problem started again this spring."

If a neurectomy is done higher than the base of the sesamoid bones, then the horse will have no sensation in a greater part of the foot, and stumbling becomes a problem because the horse cannot feel his foot. Kye is now living in retirement in Central Kentucky, with careful attention paid to his problem foot.

Reimer feels that for Kye, the series of neurectomies were successful because, "Kye originally was an euthanasia case, and he got three fun years doing what he liked, and his attitude improved after the pain was removed with the neurectomy."

About the Author

Barrie Grant, DVM, Dipl. ACVS

Barrie Grant, DVM, Dipl. ACVS, is a board certified surgical veterinarian specializing in equine wobblers and cervical stabilization. He is a former partner in the San Louis Rey Equine Hospital. He left SLREH in 2008 and now has a consulting practice in Bonsall, Calif., where he enjoys surgery and working with veterinarians and their clients. More information about Dr. Grant can be found at his website,

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