Nerving: (Posterior digital neurectomy) A Farrier’s point of view

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The above video shows Dr Marc Smith DVM of Natchez Trace Veterinary Clinic performing a neurectomy.

 

Farrier Scott Simpson shares his thoughts on the controversial issue of “nerving” in horses.

Introduction

This work is based only on experience. Not all of it is my own. Much of what I present here has been learned from discussions with scores of equine practitioners. I have seen numerous cases where horses have led a pain-free serviceable life following neurectomy. The longest was more than 10 years, the shortest was 18 months. The majority were relieved of pain for at least 5 years or the remainder of their active service to their owners. I have only been involved with two horses which received no relief from the procedure. I have owned and roped off a fifth-year neurectomized horse.

Chronic lameness unresponsive to other treatment

The subjects of this presentation are horses with chronic, grade 3 plus heel soreness and display an attitude of constant toe pointing while at rest. The quality of life of horses affected with chronic heel lameness is not good. We often condemn these animals to life at hard labor without parole. They are victims of constant, 24- hour-a- day pain. The majority of these horses will perform at speed without noticeable discomfort and their ability is seldom impaired to the point of mandatory retirement, sometimes for years. They all trot lame exhibiting the shuffling gait of the bilaterally heel lame horse or the head bob which signifies unilateral soreness.

Image from the above video of a horse undergoing a neurectomy.
Image from the above video of a horse undergoing a neurectomy.

The position of the owners, vets and farriers of these animals is: the owner expects to have the horse repaired and “it’s only lame when not shod exactly right.” So; the vet diagnoses, medicates and confirms that correct shoeing procedures should help. The farrier will, over a period of time, administers three to four procedures which do not cure the lameness problem. Honest evaluation at this point often reveals that the horse has not improved. The one thing that has probably kept these horses in service is the use of pain masking drugs. Many horses do benefit from support type shoes in the early stages of heel lameness, but we are addressing the matter of a chronic condition.

Occasionally these horses, somehow, acquire new owners. They usually come with the disclaimer that “he’s a little off if he isn’t shod just right.” More likely though, the owners become disillusioned with the vet/farrier team they have been using and change to another squad. The process begins all over again and is, more frequently than not, repeated at least one or more times. Years pass with this poor beast giving its best, but still hurting. By now the horse is usually so lame that it cannot be used nor sold in good conscience. (Who has a conscience when they’re trying to sell a horse?) Now it must be retired, put down or canned. If it is a mare she winds up in the broodmare band but she is still in constant pain. The same is true for the retired animal. Horses taken from active service probably suffer lower levels of pain, but still continue to live in the proverbial “world of hurt.”

An alternative to pain

If vet and farrier techniques have not proven successful within one year from constant toe pointing, serious consideration should be given to humanely alleviating the pain. Farrier procedures are obviously not doing the job. Posterior digital neurectomy seems to be the only answer at this time other than constant medication. I am not qualified to scientifically discuss the long term affects of the drugs currently in use. I do know that some of them are not good for the horse as a steady diet, especially in the quantities needed for relief from the pain these animals suffer. I will believe in Warfarin and Isoxsuprine therapy the first time I see them reverse a chronic case of heel lameness.

In this day and age we should rationally be able to talk about neurectomy as an alternative to unrelenting distress for chronic heel lameness. Logical, honest assessment of the problem should reveal that when everything else has failed, beginning the cycle all over again isn’t going to give the horse any relief. What does this animal really deserve? To be killed? To be jacked around for another couple of years? Or, a chance to extend its service in what we humans call “a better quality of life”.

Are the complications to PDN frequent?

There are few proponents of Posterior Digital Neurectomy. Most farriers and vets have succumbed to the horror story syndrome associated with it. Most can quote from a long list of bad things they have heard can happen to the nerved horse. Many freely admit that they haven’t actually seen most of these things themselves. The chance of painful neuroma formation is the most frequently cited excuse for not doing the procedure. It is the most logical one in terms of actuality.

This is the one thing that seems to determine the longevity factor of a successful neurectomy. Although the condition can occur, how much worse off is the horse for having experienced some period of respite from constant pain.

A very prominent equine practitioner told me that fewer than 5% of their patients returned because of neuromas. Given a factor of another 5% going elsewhere for treatment and another 5% that got lost in the shuffle and another 5% that were put down when the condition occurred, the odds still look pretty favorable to me. There also remains the option of reoperating on the horse that may develop neuromas. Loss of the hoof wall, and rupture of the deep flexor tendon are weak arguments against the procedure.

None of the dozens of horse doctors I have interviewed have seen hoof loss and only one a rupture of the DFT and that was at the insertion into P3. (His own roping horse.) Nail punctures and heel abscesses are possibilities which may occur, but they often go unnoticed in non-nerved horses. Every horseshoer has removed nails which the owners did not know were in their horse’s feet. Ask the horse whether to take the chance of dealing with these remote problems. I think you could surmise the answer if you yourself suffered chronic heel pain.

Degeneration of the articular cartilages in the joints of the lower limb has been observed in young neurectomized horses. I don’t feel competent to address this issue other than to think that very young animals are not good candidates for the procedure. Posterior digital neurectomy is not a panacea, but it certainly is a reasonable alternative to constant pain for many of these, long suffering, old friends.

Safety and the horse with a PDN

Arguments always arise about how unsafe it may be to ride a horse which has been neurectomized. No one seems to think it unsafe to ride a horse which is under the influence of pain masking drugs. What’s the difference? Evidence the association of stumbling in the horse trying to protect its sore heels and you should conclude that the unsafe ones are the ones that hurt.

PDN candidates

There is no criteria cast in “tablets of stone” for candidates for the procedure. There are diminished benefits if the neurectomy is withheld for too long. The horse’s capacity to perform may be decreased to a point where neurectomy is impractical because of advanced age. After a diagnostic nerve block has been performed, many horses which have shown heel lameness for long periods of time still exhibit a toe landing way of traveling. Although they are pain free it can be assumed that there are adhesions between the Deep flexor tendon and the navicular bone. X-rays of these feet often shows significant pathological changes in the navicular bone. In my opinion these individuals should never be considered for the procedure.

As a farrier, I have finally learned to acknowledge when my expertise and efforts are no longer helping the heel lame horse. I have learned to cope with being dismissed when my efforts have failed to to give the relief the horse deserves. I have been fired by many owners who continued to pursue some other forms of wizardry which will mend their ailing equine. When things deteriorate to this point with these chronics, why can’t we all be rationale and sensibly learn to read the handwriting on the wall? It’s tough to be straightforward sometimes, but instead of handing this poor animal another one-way-ticket to constant pain and misery, let’s try to really improve its quality-of-life or; … end it. I don’t think that euthanasia is the best option at this time, so; what’s left?

It is my opinion that the decision to perform the neurectomy should be solely the owners. If after thoughtful discussion with the team, the owner decides on the procedure, it should be done as soon as practical. As with any surgery, the choice of surgeons is a serious consideration and may require a delicate selection process. If the case vet feels the need to: he or she should readily refer.

Some newer methods improve the procedure

I am aware of new methods of performing the surgery which may be a bit more complex, but produce excellent results. I am very impressed with the contemporary concept of performing it while the patient is under a general anesthesia. This gives the surgeon a better opportunity to dissect away any tissue and accessory branches to the nerve which may decrease the chances of success. I have though, seen many horses pain free for years after the surgery was performed in a box stall or back yard using a local anesthetic.

There seems to be a broad range of fees charged for these surgeries. I am certainly in favor of professional compensation for quality services. Some veterinary surgeons charge exorbitant fees for performing a neurectomy. As the surgery does not invade muscle tissue or expose vital organs, I can’t see why it should ever be priced to the point of dissuading the owner from electing to having it performed. Certainly, there is the decision the owner must make as to whether the horse is monetarily worth the cost of surgery. Unfortunately, this choice can’t always come from the heart, but must sometimes defer to the pocketbook.

Never at any time prior to a neurectomy is the shoeing more important than after it has been performed. I am convinced that the success and longevity of a Posterior Digital Neurectomy is enhanced by meticulous attention to the principles of balanced, supportive horseshoeing. Front shoes should be left as long in the heels as the horse can wear and toe breakover should be eased to some degree. As most of these animals are performance horses, heel length must be practical to the activity. Shock absorbing pads may be indicated for some activities.

Identification

Transference of ownership of a neurectomized horse can be a touchy situation. If the horse is pain free and moving well the seller often fails to mention that the horse has been nerved. In some cases you couldn’t place a bigger stigma on the horse than if it had chronic laminitis. Many of these horses have some feeling in the heel bulbs making them difficult to detect during a prepurchase exam. Ethically, an international system of permanently identifying these animals could eliminate the question: “has it or has it not?” A simple lip or ear tattoo could tell the story. Some innovative clinic or teaching institution could pioneer the system.

We farriers are under the most pressure in dealing with the clients as we attend to the horses on an regular basis. This is quite difficult because so many of these horses come to us in advanced stages of heel lameness and nothing we can do helps the condition. We feel compelled to try although we know we are kidding ourselves. There is a difference between shoeing a horse better and shoeing one sound. No-one can shoe one of these horses sound, so it’s time to quit pretending that what we do is really making the horse feel better. We should be up front with the owners and tell them how it really is.

Conclusion

Owners must learn to face the reality and gravity of the situation. They need to learn and accept what the farrier and veterinarian can and cannot do for their animals and face the reality that these horses are not going to get well. The owner also needs to make the “ultimate” decision.

Scott Simpson demonstrating on stage at a Diamond Horseshoe "Working Farrier" event at the American Farrier's Association Convention.
Scott Simpson demonstrating on stage at a Diamond Horseshoe “Working Farrier” event at the American Farrier’s Association Convention. © Fran Jurga

Veterinarians, you can learn the procedure well and use it as the customer directs. The interim relief is in your hands. The ultimate relief may be in your hands too. For now, let’s keep a more positive thought.

J Scott Simpson (1933 – 2012) was the author of numerous books on horseshoeing, the culmination of which is his magnum opus, The Contemporary Horseshoer: Shoeing Horses in the Twenty-First Century. He also wrote numerous articles in journals and magazines ranging from Western Horseman to Plane & Pilot. He also helped to establish certification for professional farriers, developed the “Eagle Eye” principal of shaping a horseshoe to an individual horse’s foot, and invented numerous implements for farriers, horsemen, and aviators. 

Simpson acquired his first horse at the age of 18, which established the direction the rest of his life was to take. He became skilled first as a cowboy and rodeo rider, then as a horseshoer, graduating from the California Polytechnic horseshoeing school in 1959. After 17 years as a professional farrier, he founded the Horseshoeing School at Montana State University in 1970. He later became the instructor of farrier science at Walla Walla Community College in Washington, and at his own Northwestern School of Horseshoeing. He served as president of the American Farrier’s Association, and received the AFA’s Outstanding Educator, Outstanding Clinician and Outstanding Journalism awards. In 1999 he was inducted into the International Horseshoeing Hall of Fame at Churchill Downs in Louisville, Ky. 

This article, which first appeared on Horsetalk.co.nz in 2005, is reprinted with permission from Horseadvice.com, an internet information resource for the equestrian and horse industry since 1994. It has tens of thousands of documents on the web about horse care, diseases, and training.

3 thoughts on “Nerving: (Posterior digital neurectomy) A Farrier’s point of view

  • July 20, 2015 at 5:31 pm
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    This article makes me sad. This is such an old fashioned idea now that new research from the Michigan Univeristy Hoof Laboratory has shown why these horses suffer caudal heel pain and navicular syndrome. Understanding the processes that created this pain and bony changes allows you to deal with them without invasive procedures. No horse needs to suffer this type of therapy now. Vets & farriers should know more about this as its an animal welfare issue that they do not!!

    Caudal heel pain is a consequence of the crushing of the internal tissues of the hoof and the damage that occurs there from the inflammatory chemicals released due to this. It is due to long term hoof deformation from to shoeing and shoeing even corrective shoeing, to match an ever deforming hoof just speeds up the damage.

    Barefoot trimmers are turning around these cases every day and once the hoof capsule is coaxed into a more biomechanically correct form there is no need to perform neurectomies or other invasive procedures as the pain abates and the tissues recover. Many of these horses can be ridden again with boots and pads and some even go back into competition work. Looking at what has always been done that has not been successful, is not a good option for the horse or its owner. Its time to look at what others are achieving.

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    • September 8, 2015 at 1:08 am
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      Totally agree with above post. There is no such thing as Navicular it a made up disease like my others caused by shoeing horses. The true cause is being proven to be toe first landing and shoe vibration damage. The key to reversing this condition which has been proven in thousands of cases is back of the foot development.
      Dr James Rooney first looked into navicular problems over 40 years ago and published a paper in 1974 that basically said that there was no such thing. Rooney studied thousands of hooves of so called navicular horses and just like Bracy Clark’s findings on shoeing horses 150 years earlier they have been ignored by farriers and vets alike. There is no scientific proof that navicular disease exists, so much so they have started to call it navicular syndrome, meaning it’s somewhere in the back of the foot, but we can’t find it. Basically navicular problems are caused by toe first landing, quote by Pete Ramey on the subject.” In a toe first landing however, the descending fetlock joint is still tightening the tendon just after impact, but after the toe impacts the ground, then heel rocks downward, tightening the tendon at the same time. Understand that in a heel first landing we have one pulley tightening as the other is releasing tension, but with a toe first landing, both pulleys are tightening at the same time. Far greater force is directed to the navicular pulley than was ever intended by nature.” So all we need to do to cure this so called progressive and incurable disease is to take the shoe off, trim their hooves properly to facilitate a heel first landing and turn them out in the field for 6 months so they can develop the back of the foot.

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  • October 3, 2017 at 2:20 pm
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    i have rode horses that have been nerved. i was on the way to being a jockey. i could hold a horse together with bad knees, ankles an such, so they could run better. however, a nerved horse, does not know where its foot is(hoof). they are lopsided, and take bad steps. it is not fair to the horse. it is not fair to the rider. to understand how this works, numb your wrist near the ulna bone, and use the dominate hand, where it is numbed. then try to function. if you cant solve the underlying problem, it is of no use. I.E., i have a toothach, to fix it, i just sever the nerve going to that tooth. that tooth does not hurt anymore, therefore it is better. //Ed

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