The Art of Therapeutic Shoeing
Michael J. Wildenstein, resident farrier at Cornell University's large animal clinic, has approximately 400 different types of therapeutic shoes hanging on the wall of his clinic. Each one, he says, was made for a particular lameness or disease problem to fit an individual horse: aluminum shoes for a fatiguing jumper, plastic shoes for an endurance horse, rubber shoes for a carriage horse, titanium shoes for a horse who wears down its shoes too fast, glue-on shoes for thinned-walled horses. About 98% of them are nail-on shoes. His arsenal also includes bar shoes, shoes with frog supports, plastimer plastics for cracks, acrylics for hoof reconstruction, pads, metal plates, and even regular steel shoes.
Rob Sigafoos, chief of farrier services at the University of Pennsylvania's New Bolton Center, is a pioneer in adhesive technology applications for athletic and injured horses. He pioneered the use of "hoof repair compounds" to rebuild underrun heels.
"The list can be very long," he concedes. A journeyman farrier certified through the American Farrier's Association (AFA); schooled in his trade at the Agricultural School in Turo, Nova Scotia, Cornell University, and the Royal Veterinary School in Denmark; instructor for Cornell's farrier, veterinary, and agricultural students, and the farrier for Cornell's referral and resident horses, Wildenstein has the credentials and experience to back up his beliefs.
Down south a ways, more than 99% of the shoes used by Rob Sigafoos, Wildenstein's counterpart at the University of Pennsylvania's New Bolton Center, are of the glue-on variety, primarily plastic and aluminum combinations.
"I very strongly believe that one of the biggest problems horses have with structural wall failure, hoof cracks, wall separation, and dishing of the feet can be traced to having nails in their feet," Sigafoos states. "I think nails weaken hoof walls too much. Weakened walls tend to collapse over time."
In contrast, he says, glue-on shoes don't violate the integrity of the hoof wall; they stay on better than nail-on shoes and hold up well in competition.
"Bruce Davidson won a five-star three-day international in them several years ago," he says.
Sigafoos bases his theories on extensive experience and research. As an AFA certified journeyman farrier, he is chief of farrier services at New Bolton Center, providing therapeutic farriery to outpatients and hospital cases. He also heads a new $250,000 horse shoe research laboratory.
Scott Pleasant, DVM, clinician and instructor, large animal surgery, Virginia-Maryland Regional College of Veterinary Medicine, has a few credentials and opinions of his own. Pleasant, who also studied and worked as a farrier, has researched navicular disease and laminitis, and maintains a special interest in foot-related lamenesses. He believes glue-on shoes have a role in therapeutic farriery, but that they do not hold up well for everyday use.
"Placing nails in horses' feet is probably not the best thing," Pleasant states, "but until something matches that standard, nailing on shoes is the best method in most cases."
In fact, Pleasant believes that the type of shoe used in therapeutic farriery isn't anywhere near as important as getting the hoof angles and balance correct, providing proper foot support, and applying the shoe correctly.
Three hoof problem specialists, three approaches to therapeutic farriery. It's no wonder that owners and trainers are bewildered and that solutions can differ amongst farriers and veterinarians in "ordinary" practice. But considering equine scientists have yet to define what a normal hoof should look like, it's hardly surprising that they disagree on how to treat a problem hoof.
"More scientific evidence is needed to determine what type and material of shoe are actually best," says Pleasant. "Most everything now is based on speculation and personal preference."
Even with tremendous resources only a keystroke away, therapeutic farriery solutions often boil down to best guesses and trial-and-error. Factor in how these individual conditions--breed, conformation, type of work, terrain, etc.--might alter what is applied or how it is applied to a distressed foot, then the conveyance of broad-based treatments of hoof problems comes down to offering variable guidelines rather than simple, precise answers on how to treat a hoof.
Problems, Answers, And Alternatives
Navicular disease is a degenerative disease of the navicular bone, the deep flexor tendon that exists behind it, and the bursa (a sac between the bone and tendon). Although there is no cure for navicular disease--once the bones are damaged, they remain damaged--there is management.
"Possibly with the exception of nuclear scintigraphy (bone scan), navicular is diagnosed by exclusion, and many people feel navicular is dramatically overdiagnosed," says Sigafoos. "Many, many diseases very closely mimic navicular disease, and they are not necessarily treated the same way."
Pleasant agrees diagnosis can be tricky. He begins with the horse's past and recent history, a thorough physical exam of the whole body, and a detailed exam of the musculoskeletal system including limbs, joints, and, using hoof testers, the feet. He then looks for lameness and abnormal gaits or movement in the limbs as the horse is walked and trotted in hand, lunged, and, if necessary, ridden by the owner or trainer under tack.
After lameness is localized to a specific limb, Pleasant performs a nerve block to further isolate the source of pain.
"With navicular disease, we do a nerve block at the level of the horse's heel and expect to see a marked improvement in the gait after the nerve block," he says.
If the horse demonstrates marked improvement with the nerve block, Pleasant proceeds with radiographs of the navicular bone and its associated structures.
"Certain changes on X rays confirm a diagnosis of navicular disease," Pleasant says. "But in some instances, there may not be radiographic changes, especially in early cases. In those cases, we base our diagnosis on history and clinical findings. Since navicular disease is often the worst case scenario, we often treat for it, regardless of what the radiographs show."
Slightly more specific nerve blocks of the navicular bursa or coffin joint might clarify the diagnosis, as can bone scanning.
"Treatment is 'correct' rather than 'corrective' hoof trimming and shoeing," Pleasant states. "In most cases, trimming and shoeing are not as they should be; it's rare to see a horse that's properly trimmed and shod showing signs of navicular-type pain. Incorrect or poor trimming and shoeing can be a strong factor for predisposing horses to navicular disease, because it places abnormal biomechanical forces on the navicular region.
"Our goal is to reduce the abnormal forces on the navicular region," Pleasant continues. "We establish a matched hoof and pastern axis, meaning the slope of the dorsal surface of the horse's hoof would be parallel to the angle of the pastern. In many instances, horses have under-run heels, so we try to balance the horse's hoof and shoe them in a way to encourage proper and more upright growth of the heels. Most often we use a wide-web type shoe with a modified toe to help dissipate concussion and to ease breakover."
Pleasant favors a wedge type of wide-web shoe made of aluminum, although he adds that his choice of aluminum is based on personal preference, and that shoe material "probably doesn't make a huge difference."
Wildenstein says, "We generally reduce the concussion via a very high-quality pad or urethane or rubber shoe, maybe give the hoof more support with a bar shoe to elevate the heel."
He also recommends increased warm-up periods, to get the blood circulation going and make the horse more fluid and easier moving, and reduced work-outs, as the sporting activity sometimes leads to or aggravates the problem.
Sigafoos charges that, "The standard way of treating navicular disease by elevating the heel and putting a wedge pad and eggbar shoe on is questionable. It's a last-ditch effort, not a legitimate thing to do initially. As you elevate the heels, you decrease loading on the deep flexor tendon, which decreases compression of the navicular bone against its articulation of P2 and P3. This is great, but over time--some say hours, some say days--the deep flexor tendon goes back to its original loading, so theoretically you end up with the same amount of compression on the navicular bone."
Sigafoos cites a study that showed less than 10% of horses shod with elevated heels, wedge pads, and eggbar shoes remained sound after two years.
Additionally, Sigafoos warns that if this procedure is applied to badly under-run heels, which are similar to and sometimes mistaken for navicular disease, the horses will feel more comfortable for up to a week, but usually within a month will "break their heels down really severely--their heels collapse more and the bruising gets more pronounced."
Instead, Sigafoos recommends treating navicular disease by first correcting any mechanical detriment to the foot, like long toes, under-run heels, etc., reducing concussion to the foot, placing the horse on anti-inflammatories, and using light exercise to keep them moving instead of just standing in the stall. Sigafoos uses a variety of shoes to reduce concussion, but currently is favoring a plastic/aluminum glue-on shoe with an ethylene vinyl acetate foam component, a material for extra comfort similar to that used in Nike or Reebok running shoes.
Under-run heel is a condition in which the horse's heel is more sloped than it should be.
"Some refer to this angle as being five or more degrees less than the angle of the toe," explains Pleasant. "Ideally, we like the heel angle to be the same as the toe angle."
Under-run heels place the heels farther under the hoof than ideal, increasing concussion through the structures in the back part of the horse's foot.
"Under-run heels really load the navicular region and can cause navicular-type pain, heel bruising, and laminar tearing," Pleasant warns.
Causes include conformation faults or improper trimming and shoeing.
"Short shoeing, where the heels of the shoes aren't set as full or long as they should be, encourages the under-running or acute angulation of the horse's heel growth," explains Pleasant.
Because it takes a long time to change the direction of hoof growth, treatment usually is difficult and lengthy.
"We try to remove the heel down to where there is quality hoof wall," says Pleasant, "then set the heels of the shoes back to the point where we think they should be. Over time, we hope this would encourage the heels to grow in a more upright manner."
Arthritis is the acute or chronic inflammation of a joint or joints. The disease is degenerative and has no cure, but treatment can prolong a horse's active life by reducing pain and allowing more comfortable movement.
Diagnosis is similar to that of navicular disease--history, physical exam of the whole horse and musculoskeletal system, and observing the horse's way of going. If the pain source isn't obvious, radiographs and/or nerve blocks can be performed.
Options for treatment are based on type of horse, use, and amount of arthritis already present.
"Certain types of corrective or therapeutic shoeing may protect or support damaged joints or tissue," says Pleasant. "We trim the horse in a way to relieve stress and strain on the injured area--not anything fancy, but with proper angles and support, and to make the limb very easy to break over, in most cases."
Low dose anti-inflammatories also are administered.
Foot bruising often is seen on horses subjected to very hard or rocky ground. Diagnosis relies on history, physical exam, and hoof testers to isolate the specific region of hoof pain. Sometimes nerve blocks are used to confirm the troubled area and radiographs to rule out other causes. Occasionally, areas of hemorrhage are visible.
Bruising, especially deep bruising, can take weeks to heal.
"The most overlooked treatment is rest," Pleasant states.
Horses with mild bruising can get by with reduced workouts, particularly on offensive surfaces, while more severe cases might require stall confinement.
Additionally, Wildenstein recommends reducing trauma and concussion through shoes and pads.
"If the bruising is affecting the bone," he says, "we may use an aluminum or metal plate to prevent bruising from re-occurring."
Hoof cracks have any number of causes.
"Usually they are created by an injury, whether the horse hits itself or is hit against something else," says Wildenstein. "Maybe he jumps repetitively, or has an imbalance or a limb deviation that puts unequal stress on the hooves. Maybe the hoof has been improperly trimmed or shod, creating an imbalance. Cracks also come from hoof abscesses and weakness in the laminae."
Adds Pleasant, "Hoof cracks usually don't occur in normal hooves. They happen because there is an imbalance of the horse's foot or excessive length."
Diagnosis is made through visual observation.
Treatment means addressing the underlying cause--interference, injury, incorrect shoeing. This helps in repairing cracks and avoiding new ones.
"The most important thing is balancing the horse's foot," says Pleasant. "The cracks themselves can be treated in a variety of ways. Most often, if you correct the underlying cause, the cracks will grow out. We might be able to stabilize minor cracks with clips on the shoe on either side of the cracks. In more serious cases, we debride the cracks and rebuild the hoof wall with a hoof repair system such as Equilox."
Laminitis is one of the simplest and most obvious diseases to diagnose.
"Usually, diagnosis is made by physical examination and demonstration of pain, particularly in the toe region," says Pleasant. "Signs are being sore footed, with reluctance to walk or to pick up one foot and stand on the other one. Horses are often sore to hoof testers over the toe."
Radiographs are useful for evaluating the alignment of the coffin bone and hoof capsule, and for looking at "sinking" or rotation of that bone. Generally, nerve blocking isn't necessary.
Laminitis occurs in three distinct phases.
"In the development phase, the horse shows no symptoms," explains Sigafoos, "but vascular changes are occurring in the horse's hoof. The horses are starting to get pooling of the blood, some vaso-constriction, and some vaso-shunting, where the blood is diverted away from capillary beds in the laminae and being shunted back up to arteries to the main portion of the body. They (horses) are not painful, can turn well, and usually have increased digital pulses, but not always. The only thing you'll find is the feet are cold--no heat in the feet, whatsoever. This stage usually last 12-24 hours."
Next, horses go into the acute phase. "This is when the horses start to become very painful," Sigafoos says. "They'll point their feet out in front of them, they will be very difficult to turn, they'll get increased digital pulses, and you'll usually see a lot of heat in the feet.
"It's very important that owners recognize when their horses are in acute laminitis, because laminitis is a life-threatening disease. As soon as they suspect the horse may have laminitis, they should call their veterinarian immediately, and make sure the veterinarian gets out there immediately."
The acute stage can last up to 72 hours, before the horse either improves or goes into chronic laminitis, the final stage.
"Chronic laminitis is signaled by any permanent change seen in the foot, such as rotation or sinking of the coffin bone," says Sigafoos. "Once this occurs, the laminae are damaged and will never regenerate normal laminae again. Horses will be more likely to develop an abscess, subsequent bouts of laminitis, and will become higher maintenance and higher risk, although horses with minor rotation may become competitive again, depending upon severity of damage."
Addressing the underlying cause of laminitis is paramount in treatment. Causes include retained placenta, nutritional compromise, and limb injuries, resulting in disproportionate weight-bearing on the opposite limb. Medications that improve blood flow and circulation to the blood vessels that feed the laminae, and shoeing and trimming to relieve some of the stress to the laminar region, are utilized.
"There is considerable debate on what type of trimming and shoeing is most appropriate: the range goes the complete 360 degrees," says Pleasant. "We try not to change the horse's angles too much when they are sore; I like to reduce the prying effect of the toe by severely rocking the toe. I apply some form of frog support that is initially taped on the horse's foot rather than nailed on."
Pleasant also tries to support the coffin bone and reduce weight-bearing on the hoof wall by bedding the horse in a sand stall.
Sigafoos uses a similar approach. He shortens excessively long toes to ease breakover, enabling the horse to get its feet off the ground with minimal stress on the laminae on the front of the hoof wall. He says, "When the foot breaks over, the deep flexor tendon pulls on the underneath side of the coffin bone, tending to pull on the laminae in the front of the hoof. A normal hoof can withstand this without any trouble, but when a horse starts to develop laminitis, any excess toe length causes increased tensile load on the laminae, exacerbating the disease."
When the laminitis is in the acute stage, Sigafoos uses tape and foot bandages.
"I don't even glue shoes on them at this point," he states. "I tape them on. I'm a real believer in foot bandages; you can put foam rubber or a variety of other things on them. If you find the horse is less comfortable with what you did--and almost invariably with laminitis you don't find the optimum solution for them (horses) immediately--you can change what they have on without any trauma."
After the acute stage passes into the chronic stage, Sigafoos applies a glue-on shoe to provide sole or frog support.
"I believe very strongly that the treatment should not require nailing shoes on foundered horses' feet," Sigafoos emphasizes. "The hoof wall is already compromised, and driving nails in traumatizes the horse's foot, tends to pry the hoof walls apart, and makes the hoof even more damaged and weakened."
Shoe material depends on the size of the horse, degree of the disease, and other factors.
"Generally, I use a glue-on with a very, very slippery bottom surface. Absolutely no traction," Sigafoos says. "This reduces any trauma or torque on the bottom of the foot as the horse turns on it. The horse can fully load the shoe, turn on it, and the foot itself turns, not the hoof with the bone inside the hoof wall."
Injuries involving tendons or penetration of the hoof are sometimes aided by therapeutic farriery.
Tendon injuries can be treated by the application of a special high heel. "This allows us to take the tension off of the tendon while the horse is at stall rest," Wildenstein explains. "Over time, we gradually lower the heel to allow the tendon and muscles to stretch out again."
With penetration injuries, Wildenstein applies a treatment plate. This place has a bottom or base on the shoe that can be removed so that medication and bandaging can be changed daily to help in the healing process.
Toe-in, and toe-out conformation are genetic deviations where the horse's feet turn in or out rather than pointing forward. The condition can often be corrected in horses under four months of age, as their bones are still growing and malleable. Therapeutic shoeing options attempting to correct older horses are very limited.
"What we often do with a young horse that toes in or out is to put the shoe, in a sense, where the foot should be and isn't," says Bill Moyer, DVM, professor and department head of large animal medicine and surgery, Texas A&M University. "The principles are similar to the efforts used on young, growing children to straighten out various abnormal limb conformation abnormalities, with the little white shoes and the bars between them."
Glue-on shoes often are used in youngsters, as nails can damage small hooves.
"Once the adult stage is reached, the ability to de-rotate the limb is pretty much over," says Moyer. "You can use the same principles to minimize the problem, but to a lesser degree. For a horse that badly toes in or out, we fit the shoe where we would like it to be knowing it will never be there, but providing some artificial support. Whether such measures prevent injury as the horse's career proceeds is difficult to evaluate."
Sigafoos says that many foals outgrow this condition, if it's not too severe. He warns that some procedures used to correct the condition can actually lead to far greater problems down the line.
"Some people change the medial to the lateral or side-to-side balance of the hoof," he says. "If the foal is toeing out, some try to take more off the outside of the foot than the inside of the foot, which does appear to toe them in more."
However, this can lead to an angular deformity, an S-turn conformation from the knee down, so that the leg rotates out and the fetlock rotates in.
"These S-turn conformations are a real bear to manage; they create a lot of hoof problems because of abnormal loading on the hoof, with structural wall failure, hoof cracks, sheered heels, and displacement of their coronet band."
Shelly feet, in which the hoof sustains superficial cracks and minor horn loss around the foot, can be due to genetics and the environment.
"Shelly feet usually aren't corrected by corrective shoeing," says Moyer. "Often the application of shoes improves barefoot horses with this problem by providing them with an artificial bearing surface. In other cases, one must attempt to change or alter environmental factors affecting the feet, which is not always easy."
Thin walls are a very common problem that can lead to recurrent lameness and difficulty in retaining a shoe. The cause is probably genetic.
"Thin walls make it very difficult for farriers to apply shoes adequately," says Pleasant. "You often get into vicious cycles where the walls are so thin that the farriers can't get adequate purchase with their nails, then the shoe comes off and you have less foot to work with."
Common treatments include using glue-on shoes to avoid putting any more nails into a troubled hoof wall, going with a very light shoe and small nails, or letting the horse go barefoot in order to grow out a new, healthy hoof. But glue-on shoes are expensive, and there is disagreement on how well they stand up for athletic use. Even small nails can damage deteriorating hoof walls, and some barefoot horses can suffer hoof breakage without a shoe.
Hoof reconstruction gives a horse a hard, new, artificial surface into which a shoe can be securely nailed, and also permits the horse to keep up an active athletic schedule.
"When the farrier can no longer apply a shoe safely, we reconstruct the foot with a resin such as Equilox, combined with a fiberglass or polyethylene fabric," Pleasant says. "This adds width and bulk so the farrier has something to work with. If the horse doesn't have sole bruising or bruising from nails, it can usually go back to its normal use shortly after reconstruction."
Unless the horse is growing its feet out, trimming and shoeing are recommended at more frequent intervals.
"It may seem backwards," Pleasant admits, "but this allows the farrier to remove the shoe and reset the nails before the shoe starts to loosen or get pulled off. When that happens, there's usually more degeneration."
Pleasant recommends using smaller nails on this type of problem.
What's The Future?
Perhaps some day, therapeutic shoeing will have a general consensus on treatment options. But experts do agree that great advances are happening. Today's farrier, veterinarian, trainer, and horse owner have become increasingly savvy about hoof care, and are working together in better, smarter partnerships. Underlying causes for lameness are coming to light.
"We're really starting to see now that the effects of shock and concussion on the foot are a much more significant factor in the chronic, insidious form of various types of arthritic, navicular, and coffin joint diseases," says Sigafoos. "We're now looking at materials that can reduce shock and concussion on the foot."
High-performance, high-impact acrylic adhesives and ongoing improvement of glue-on shoes continue to expand treatment options. And, predicts Sigafoos, like the revolution in the human athletic shoe industry, the equine shoe industry might soon undergo its own revolution with more sports-specific, lameness-specific, and disease-specific horse shoes.
All of these developments promise better answers for hoof care.
Can certain types of shoes prevent lameness or foot problems? Possibly, says Rob Sigafoos. The difficulty lies in trying to do a controlled, blind study where horses are matched in pairs and occupation, half shod one way, half shod the another way. In addition, genetics and environmental factors could play a role that alters results.
"It's never been done, and it'd be very difficult to do," Sigafoos states. "So when I read that XYZ shoes prevent lameness, navicular disease, or ringbone, it raises a red flag for me because I wonder what kinds of studies were done that really show it prevented the problem. Taking a sound horse and saying that because the way it was shod prevented it from having such-and-such a problem is a very difficult call to make."
About the Author
Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.