Feet First: Farriery Topics from the 2006 AAEP Convention
Diagnostic Imaging and the Farrier-Veterinarian Partnership
Have you ever seen a radiograph of your horse's bones? Or a bone scan? Or an MRI image of his lower limb? These diagnostic imaging modalities and others are becoming more and more common in equine veterinary medicine, and their increased availability is changing the way veterinarians and farriers work together to maximize the health of the horses they tend.
Harry Werner, VMD, of North Granby, Conn., and AAEP's new vice president, discussed diagnostic imaging and the veterinarian-farrier partnership for a standing-room-only crowd.
The session during which he spoke, called Putting Science Into Farriery and sponsored by Vettec and Equilox, was the first session at the AAEP convention that has been open to farriers.
"Innovative technology now enables the farrier and veterinarian to work even more collaboratively to evaluate a horse, establish management and treatment options, and evaluate case outcomes," he said. "I feel like I'm most productive when I'm part of a team--including the owner, veterinarian, trainer, and farrier--all with the goal of helping the horse. If you pull anyone out of that team, productivity is impacted; nowhere is that more true than with the farrier."
Hoof Balance vs. Hoof Mechanics
A horse's foot is a complex piece of bioengineering, and its form adapts to the stresses placed on it. Evaluating such a fluid structure to identify problems and solutions is no less complex, but it's not impossible. Mostly, one just needs to have a keen eye and an understanding of hoof and limb anatomy and function.
Michael Wildenstein, American Farrier's Association Certified Journeyman Farrier, Fellow with honors of the Worshipful Company of Farriers, member of the International Horseshoeing Hall of Fame, and Cornell University's resident farrier since 1991, discussed evaluating hoof balance and hoof mechanics.
Hoof balance and hoof mechanics might sound similar, but they're not. Hoof balance refers to the shape and condition of the hoof only, from the hairline down, while hoof mechanics takes into account all forces that affect that hoof, explained Wildenstein. These might include limb conformation, injuries, rider balance, and many other factors.
In other words, hoof mechanics result in the hoof balance you see. Thus, hoof balance (or imbalance) can tell you a lot about the mechanics that shaped that foot. Understanding the forces at play helps you figure out how to manipulate those forces to reduce any abnormal stresses and gain a sounder and/or better-moving horse.
Laminitis Can't Take the Cold
Picture this: You head out to do the evening feeding at the barn, only to find that one of the horses beat you to it--he's up to his ears in a bag of his favorite feed. You've heard that feed overload can cause laminitis, so you know he's at risk. What can you do? Stand him in an ice bath.
Andrew van Eps, BVSc, MACVSc, a resident at the University of Pennsylvania, discussed research on the value of cryotherapy (cold therapy) in preventing laminitis. Van Eps, who has studied with laminitis researcher Chris Pollitt, BVSc, PhD, director of the Australian Equine Laminitis Research Unit at the University of Queensland, Australia, said previous studies have shown that cryotherapy can be very effective in preventing laminitis when applied in the developmental phase, shortly after the causative insult (carbohydrate overload, retained placenta, colitis, etc.). However, those studies have not generally watched horses for long enough to find out if laminitis could still have occurred after therapy was discontinued at about 48 hours, he noted.
"Cryotherapy is an effective first-aid strategy for many conditions in animals and people," said van Eps. "And scalp cryotherapy prevents alopecia (hair loss) in patients undergoing chemotherapy. It has fallen out of favor, but it protects cells because vasoconstriction (narrowing of blood vessels due to the cold) decreases delivery of the drug to the scalp cells and induces hypometabolism (slowed metabolism). This results in decreased activity of the drug. Similarly, agents that reduce digital perfusion (blood supply to the foot) and/or metabolic activity may prevent laminitis (by reducing the delivery and/or activity of laminitis trigger factors)."
In laminitic horses, cryotherapy is applied during the developmental phase of laminitis for up to 96 hours, up to mid-cannon level, he noted. "You need a refrigerated pump, and a tub is easiest for all four limbs," he said. "We're working on a dry membrane boot system that can be applied in the stall, where you run the lines up to the ceiling."
How to Manage White Line Disease
What is white line disease (WLD), and why is it so important to dig holes in your horse's foot to treat it? Stephen O'Grady, BVSc, MRCVS, owner of Northern Virginia Equine in Marshall, Va., and a member of the International Equine Veterinarians Hall of Fame, discussed this frustrating disease and how to manage it.
"White line disease can affect a horse of any age, sex, or breed," O'Grady began. "One or multiple hooves may be involved, and the affected hooves can be barefoot or shod. One or multiple horses on the same farm may be affected, and the problem occurs worldwide. Multiple causes of white line disease have been proposed, but none have been proven."
What is white line disease? "The term describes a keratolytic process (one that breaks down keratin, a structural protein of the hoof) originating on the solar surface of the hoof wall," explained O'Grady. "It is characterized by a progressive separation of the inner zone of the hoof wall (separation of the outer wall from the inner structures). The white line is the softest part of the hoof wall, so it's the focal point of any pressure or stress placed on the wall. White line disease can be found anywhere around the wall."
White line disease is not very well understood yet, but the sequence of its occurrence is one aspect veterinarians and farriers have a handle on. "White line disease always occurs secondary to hoof wall separation; it's not a primary problem," stated O'Grady. Once wall separation occurs, it is commonly thought that opportunistic fungi and/or bacteria invade the area and begin destruction. Many different organisms have been cultured from WLD horses; no specific causative pathogen has yet been found, he said.
Preparing Hoof Defects for Composite Repair
Have you ever had a horse's chipped or cracked foot repaired with an expensive epoxy or acrylic job, only to see it fail before its time? "A major reason for defect repair failure using composite repair materials, regardless of the technique chosen, is inadequate preparation of the defect and surrounding hoof wall and disregard for detail in handling the adhesives," said Bill Moyer, DVM, professor and head of the Department of Veterinary Medicine at Texas A&M University. He discussed proper preparation of hoof wall defects for repair and adhesive handling during the convention.
Radiographing the Foot
Portable digital radiograph (X ray) machines are very common today, and their convenience has resulted in more frequent use of the technology to diagnose hoof problems. Additionally, their high-quality imaging capabilities have resulted in veterinarians finding more pathology (abnormalities) in the foot than many previously suspected. Jay Merriam, DVM, MS, of the Massachusetts Equine Clinic in Uxbridge, Mass., gave a presentation on how to radiographically assess the equine foot.
"We are assessing the hoof radiographically a lot more than we used to," he began. He discussed how today's digital radiographs can reveal great detail about soft tissue structures in the hoof, and how that detail and instant feedback has made digital radiography a valuable tool for assessing problems such as white line disease, abscesses, hoof balance, laminitis, and monitoring response to surgery.
Hoof Wall Resection to Treat Coronary Band Prolapse
"Coronary band prolapse caused by severe abscessation is a life-threatening complication of severe laminitis," said Carrie Gatke Long, DVM, MS, of Versailles, Ky. She described her procedure for resecting (removing) part of the hoof wall and using amniotic membrane on the wound to promote healing.
Shoeing Horses With Palmar Foot Pain
How do you treat sore feet on a 1,000-pound-plus horse that can't be put to bed to allow them to heal? The stresses on those feet are enormous, and every horse's feet are different. Thus, treating horses with palmar foot pain (soreness in the rear half of the foot) requires a strong knowledge of hoof biomechanics, and flexibility to adapt treatments for individual variation.
"There is no prescription for shoeing horses with palmar foot pain," said O'Grady. He discussed considerations in shoeing these sore horses.
Despite there being no set shoeing or trimming treatment for palmar foot pain (mainly because the pain could arise from so many different structures within that section of the foot), proper foot care and manipulation (whatever form it takes for an individual horse) is still essential. "Podiatry generally will form part or all of the treatment for foot pain," stated O'Grady. "Seldom does one have a case of palmar foot pain without primary or secondary hoof capsule distortion."
How to Evaluate the Equine Foot
Evaluating the foot is essential in purchase examination and lameness evaluation scenarios, and it can often help you identify hoof problems before a horse actually becomes lame. Tracy Turner, DVM, MS, Dipl. ACVS, a private practitioner with Anoka Equine in Elk River, Minn., said to evaluate a horse's foot, "You must have accurate knowledge of foot anatomy, foot balance, and the sources of pathology, and you must be willing to perform a hands-on exam. You gotta get dirty."
How to Evaluate Hoof Blood Vessels With Venograms
When a horse has laminitis, one major concern is the condition of the blood vessels in his feet, as the tissue damage common to laminitis can compromise them. And when blood vessels are compromised, the hoof tissues can't get the nutrients they need to heal. Luckily, veterinarians can visualize the hoof's blood supply by injecting contrast media and taking a radiograph. This procedure is known as a venogram, and its protocol was discussed in great detail by Amy Rucker, DVM, of Midwest Equine in Columbia, Mo.
"Venography is used often on laminitic cases as it will show pathology that's not visible with standard radiographs, so you can accurately assess the case and its response to treatment," said Rucker.
Evaluating areas of compromised blood flow can also help a practitioner determine the extent of damage and prognosis for other foot conditions, such as club feet, keratomas, pedal osteitis, abscesses. A venogram can also help distinguish between multiple conditions (telling the veterinarian that the horse has white line disease and not laminitis, for example).
Adhesives in Farriery
The development of adhesives suitable for use on horses' hooves in the 1980s revolutionized the farrier industry. These new adhesives offered the ability to treat hoof problems in ways that were previously not possible. Horses no longer had to lay up for months to heal certain types of hoof damage; their hooves could be repaired and they could go right back to work. But along with these adhesive capabilities came the typical learning curve of how to use these wonderful new materials. Scott Pleasant, DVM, Associate Professor of Large Animal Clinical Sciences at Virginia Tech, discussed uses and misuses of adhesives in farriery.
About the Author
Christy West has a BS in Equine Science from the University of Kentucky, and an MS in Agricultural Journalism from the University of Wisconsin-Madison.
POLL: Visits from the Vet