Articles & Information
FROM THE HOOFCARE & LAMENESS ARCHIVES
Second Bluegrass Laminitis Symposium
Dr. Nathaniel White of the Marion DuPont Scott Equine Medical Center in Leesburg, Virginia presented his findings on tendon resection for laminitis therapy at the Bluegrass Laminitis Symposium.
Dr. White recommends the procedure, which is similar to the technique used to remedy contracted tendons. He has cut the deep flexor tendon on several laminitic horses that were able to be saved for breeding. He uses the reverse shoe in conjunction with the treatment, since he feels that the horse needs a wide base of support at the heel so the toe won't lift off the ground.
Objectives of White's reverse shoe are:
1) support frog and heels
2) reduce weightbearing pressure on dorsal (front) hoof wall
3) reduce concussion.
Dr. White's justification of the reverse shoe in laminitis therapy is that it is
simpler to use than the heartbar shoe and less expensive.
In trimming the foot for the reverse shoe, White recommended an angle where the frog would extend below the surface of the hoof wall and make critical contact with the pad when it is nailed on. He removes enough of the dorsal hoof wall so that the tip of P3 is exposed. He uses a wedge pad, but would like to see a combination hard and soft pad. He cautioned that nails in the dorsal hoof wall be avoided; use heel nails instead.
Dr. White said that he always tries to wait until the prognosis is complete before nailing any shoe on a laminitic horse. If there is no response after two or three days with the reverse shoe, he removes it.
Burney Chapman gave two presentations at the Bluegrass Laminitis Symposium, as well as participating in a "Live from Lexington" dual hoof resection on a sinker syndrome case with Dr. Redden. In his first presentation, entitled "Update on Laminitis", Burney focused on two very complicated cases he has been working on in the past year. He told Hoofcare before the symposium that it was difficult to present new information, since the public hasn't really learned the basics that he presented the year before. He began with simple anatomy and laminitis terminology, then explained his cases.
While Burney's cases were far beyond the frame of reference of almost everyone in the room, he did try to cast a few gems of practical information into the audience. One was an explanation of how he opens the sole and what to expect once it is opened. This is a standard procedure Burney is forced to use, since so many of the cases he sees are advanced to osteomyelitis and proud flesh must be controlled.
Burney said that the one place to open the sole is at the junction of the laminae and the horny sole. "The old horny sole still covers, but you can flush it out from the front and you don't have sore corium as you do when you open up from the bottom," Burney advised.
Dr. Doug Leach of the University of Saskatchewan gave some interesting new insights to the condition known as road founder, a mechanically-induced type of laminitis related to concussion and weightbearing.
In normal weightbearing, according to Dr. Leach, blood returns to the heart through the circumflex vein or the coronary vein.
Road founder, however, is very different, from a vascular point of view. Dr. Leach illustrated how AV shunts control temperature and regulate pressure in tissue. AV shunts are also affected by the pH factor in the blood. Lactic acid would increase flow through the shunts. AV shunts may be opened by histamines, increased pH, endotoxins, or tension.
Equine exercise physiology has researched the release of lactic acid into the bloodstream during exertion, and the relationship between this fluctuation in the pH balance of the blood and the separation at the toe or rotation of P3 in road founder may be critical in finding a means of preventing the condition. Many farriers are currently shoeing horses that they feel may be prone to road founder--especially carriage horses working on pavement--with heartbar shoes in hopes that frog support will counteract the effects of the change in blood flow from increased concussion or lactic acid.
The change in hoof conformation called in America "rununder heels" is among the complaints high on most farriers' lists. It is a tough condition to remedy and once it begins, it seems to follow a path of inevitable destruction unless therapeutic shoeing is begun and kept up.
Dr. Doug Leach outlined the onset of the change in hoof conformation leading to rununder heels. He cited the cause as a remodelling of the ligaments of the digital cushion. Once these ligaments are remodelled, it is a very difficult task to restore them to their original state, which is necessary for the heels to return to their original state. He compared the syndrome to the legs of women who have worn spike high heels for many years. The tendons change. "The digital cushion will remodel if it is allowed to remodel," Dr. Leach warned, indicating that proper hoofcare is necessary to prevent the condition in the first place.
Sound like something from Star Trek? Dr. Redden deals with very valuable horses at his International Equine Podiatry Center in Versailles, Kentucky--horses that are sometimes too valuable to die.
At the Bluegrass Laminitis Symposium, Dr. Redden's slang crept into his presentation, and into the general lingo of the cripple-conscious crowd. One cryptic quote was that a horse had "snapped his neurons"--gone beyond the painbearing threshold until the body's systems shut down.
Every speaker at the Bluegrass Laminitis Symposium had a personal favorite tool to recommend for use in hoof resections and maintenance. Dr. Redden recommends the use of a Black and Decker Saw Rasp, available at a hardware store for about $80.
As if laminitis wasn't difficult enough already, Dr. William Moyer of the University of Pennsylvania had a few more complications to throw into the ring. Dr. Moyer pointed out that a prognosis for a laminitis case requires assessment of damage, which can be determined by evaluating the amount of pain a horse is in, observing the shape of the foot, using hoof testers to seek pain spots and to look for separation, palpating the coronet for a hot spot or sinker groove, observing the character of the sole and of the white line, and interpreting radiographs.
But what about the shape of the foot? Dr. Moyer pointed out that breed or use of the horse may be crucial in this step in evaluation. Thoroughbreds shod with the long toe-low heel method are particularly tough to work on, he noted. It is necessary to be especially careful of a prognosis on a Quarter Horse, which may be overweight to begin with, and compounded by feet that are already too small for the body weight and conformation. Finally, tough Standardbreds may actually be racing in a foundered condition.
The list could go on and on.
Dr. Leach began his presentation with a review of research done in 1983 in South Africa. Angiograms of the opposite limb while a foot was lifted were done on draft horses, zebras, donkeys, and Thoroughbreds. In Thoroughbreds, the blood was restricted at the edge of the navicular bone, the inside of the coffin bone, and at the terminal arch, where the direction of flow changes. Donkeys, zebras, and draft horses did not have the same sites of restriction when the foot was lifted.
According to Tom Dixon of Dixon Insurance Adjusters in Lexington, Kentucky, the interaction of the consulting and attending veterinarians on a case is crucial to a successful treatment. Mr. Dixon explained what happens when an insurance company takes custody of a horse in a laminitis case.
The attending veterinarian is one who is hired by the owner, and is usually the regular veterinarian who works on the horse.
The consulting veterinarian is hired by the insurance company and acts on their behalf. "He is not hired to keep the horse alive until the policy runs out," Mr. Dixon assured the audience. The AVMA code of ethics says that the consulting vet must not criticize the attending vet, nor may he visit the horse or speak with the owner without the attending veterinarian being present. The consulting veterinarian cannot take charge of the case without the consent of all involved.
The Dallmer shoe from West Germany is being utilized at the International Equine Podiatry Center, under Dr. Redden's direction. Joey Carroll, resident farrier, estimates that they have used the shoe on 400 adult horses all over the world and are still testing it.
The Dallmer shoe has been on the market in Germany for about ten years. It weighs about 12 ounces and is a plastic collar shoe with a metal insert on the ground surface.
At the Bluegrass Laminitis Symposium, Joey warned that the Dallmer shoe cannot be used on a laminitis case with a serum leak unless a window is cut for drainage.
Examples given of uses that Joey has made of the Dallmer shoe were for use with the InstaPad (pour-on pad), which needs a little lip to hold it in while setting up. Joey put little screweyes into the sides of the shoe to create a lip while the pad was setting up, then removed them.
On a mare with a wet spot, he left a hole for drainage, allowing the Insta-pad to set up around the hole.
Dallmer shoes come with two vials that must be mixed together for glueing. The glue takes about 15-20 minutes to dry.
Joey has remodelled the basic Dallmer in a number of ways, including inserting a racing plate in the collar for a horse with thin walls. The horse raced four times with the shoe on. He riveted the collar onto the shoe just as if it was a rim pad. Joey said that he felt the Dallmer shoe allowed the foot to expand and grow. He noted that the collar will sweat, and that the bottom of the foot gets moist.
On a Saddlebred, Joey used a Dallmer collar and roofing nails to attach the pad and shoe. The horse needs to be shod more often because of the moisture problem, but otherwise is doing fine in three-gaited competition.
Joey cautioned that when using any glue-on shoe, it is crucial to rasp back the hoof surface for a smooth fit, and to use acetone, ketone, or ether to clean the hoof before glueing.
The Z-bar shoe for Standardbreds has received a great deal of publicity in the last few years, ever since Nihilator seemed to win every big stakes race in record time wearing a Z-bar for his quarter cracks. Also called a "half mushroom", the shoe is much imitated, but seldom applied correctly.
At the Bluegrass Laminitis Sym-posium, Standardbred specialist Joey Carroll briefly commented on the Z-bar, showing a slide of a properly fit and constructed Z-bar. Joey pointed out that the bar must follow the medial edge of the frog and should never go across it.
(For more on Nihilator and his Z-bar, see photo and story in Hoofcare & Lameness No. 10, December 1985.)
Dr. William Moyer of the University of Pennsylvania presented a conservative approach to hoofcare management of laminitis cases at the Bluegrass Laminitis Symposium.
In acute cases, Dr. Moyer recommended squaring the toe of the unshod hoof after two or three days to facilitate breakover.
If there is separation at the toe, Dr. Moyer uses a disc sander or his hoof knife to remove it.
He discusses possible shoeing options with the owner, but rarely shoes acute cases. "If I make a mistake with a shoe it could be forever," Moyer pointed out. "I wait until the horse is stabilized, or until he needs a shoe. I don't want frog pressure, and I can't duplicate the effect of the heart bar."
Moyer said that he has used an egg bar with a squared (not rolled) toe successfully, for support under the limb.
If you are using a disc sander in your hoof resection management program to reshape the new hoof wall as it grows down, Dr. William Moyer of the University of Pennsylvania suggests that you always wear an apron. He has had a disc sander run up his thigh and right through his jeans. "That thing has lots of torque," he half-joked. "And it can leave your hands. Have someone hand it to you after it has been turned on. And remember that it may sound like a pair of clippers to a horse. Some horses don't like that." This warning applies to any use of a disc sander, which is becoming standard equipment in many farriers' work on show horses.
Isoxsuprine, hailed as a potential savior a few years ago, was knocked hard at the Bluegrass Laminitis Symposium. Promoted as a vasodilating agent, the drug has been prescribed widely in navicular disease therapy, and many parties held hope it would be beneficial in laminitis therapy as well. Dr. Moyer stated that the jury was still out, as far as he was concerned. He felt that the doses prescribed may have been too small to have had much effect. Dr. White cited poor absorption of Isoxsuprine by the intestine. "It can't get to the hoof to help," he said. Isoxsuprine has been suggested as a possible agent for helping horses with undershot heels to increase circulation and possibly help prevent navicular disease-like conditions.
Detailed information on this and many other hoofcare topics can be found in Hoofcare & Lameness publisher Fran Jurga's award-winning guide to hoofcare, "Understanding the Equine Foot".
© 1998 Hoofcare & Lameness