© J. Scott Simpson
posted here with the permission of the author
first posted on the Internet in The Horseman's Advisor
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 currently own and rope 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.
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, administer 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 effects 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 his patients
returned because of neuromas. Given a factor of another 5% going elsewhere
for treatment, 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 operating again 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
rope 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 show 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 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 rational 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 owner's. 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 backyard 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 a 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.
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.
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