Healing Hooves With Self-Adjusting Palmar Angles (Bluegrass Laminitis Symposium)

Massage is a wonderfully relaxing, healing experience. As you stretch out comfortably on the table and the massage therapist's hands alternate pressure and release over your sore muscles, they begin to relax, blood flow improves, and you begin feeling better. Why else would you get one?

The same principles apply to your horse's feet. When they are compromised due to disease processes such as laminitis, or poor internal hoof balance that leads to poor blood flow and overstressing of internal structures, putting the feet in comfortable alignment and applying massage helps them heal. The main difference between this situation and your massage is that the horse does it himself.

Ric Redden, DVM, founder of the International Equine Podiatry Center in Versailles, Ky., discussed massaging hoof circulation with self-adjusting palmar angles at the recent Bluegrass Laminitis Symposium, held Jan. 25-28 in Louisville, Ky. His approach is simple--he applies shoes with curved ground surfaces (termed banana shoes, rock and roll shoes, or full-motion rocker shoes) that allow the horse to stand with his feet at whatever angle is most comfortable. This will be the angle that relieves the most pressure on any damaged areas, allowing them to rest and heal.

Additionally, the very nature of the curved shoe means the horse's hoof and bone angles will shift a bit as he shifts his weight, even if his feet never leave the ground. This is where the massage comes in; as the horse's weight and his anatomy shift, the blood supply within the foot is continually altered and massaged.

"The ability to adjust the palmar angle (the angle the wings of the coffin or third phalanx bone make with the ground) while in the static state (standing still) sets the mechanical advantage of this shoe well above those that do not influence the static palmar angle," he explained. "Square toes, rocker toes, rolled toes, and flat shoes set back under the toe to decrease breakover effort can offer advantageous mechanical action when the horse is moving, but fail to allow self-adjustment when resting."

What Kind of Problems Does it Solve?
Growing thicker soles/walls Redden uses this shoe often to treat thin hoof walls and soles, whether they are due to genetic influences, excessive moisture, too much athletic demand on the foot, etc. "Using the full-motion rocker shoe as a tool to aid quick hoof mass recovery is one of its most promising assets," he commented.

A healthy sole should be 15-18 mm thick on a typical light-breed horse, he said, to provide support for the internal structures and allow room for blood to flow beneath the bone and nourish the growth centers that grow the sole. One measures sole depth with radiographs (X rays) that focus on the coffin bone; he showed several before and after radiographs showing notable sole growth with the full rocker shoe.

"I know of no other way to get this kind of growth with one shoeing," he stated. The increase in blood supply with the shoe's massaging action and variable load conditions (i.e., not standing flat and unmoving on a foot for long periods) are what enable the sole to grow more quickly than before.

As for whether the horse can work with the full rocker rail shoes on, he said this: "I would gallop a racehorse in this shoe, but I wouldn't let him have any speed. It's a heavy shoe with a lot of mechanics. I'll put them in a lighter rocker race shoe for that and they can stay in that a long time. (Redden uses several variations on the rocker shoe depending on the case and the horse's activity level.) I'll have them in that shoe twice before letting them breeze. It's a tremendous change for the animal, and he needs time to find his balance even though you're helping his feet."

Underrun heels Growing a lot of foot quickly is also desirable in horses that have crushed, underrun heels, he noted. "The underrun heel is the result of digital cushion compression without recall," he explained. "As the support cushion becomes compressed and compacted, the palmar angle decreases, in turn producing a broken-back hoof-pastern axis."

A healthy palmar angle should be 3-5� (with the heels of the coffin bone higher than the toe), but he reported that many horses have a palmar angle lower that this, even into negative degrees. "This degree of imbalance is not compatible with longevity and is often associated with compensating leg injuries and catastrophic breakdowns," he said.

The palmar angle can be adjusted to varying degrees based on the design of the shoe, which is planned relative to the degree of damage and the activity the horse will be doing. The higher the mechanical score on the shoe (each score point means the shoe raises the palmar angle two degrees), the more the horse can adjust his palmar angle, but the less activity he can do while wearing that shoe, he explained.

"You have to be careful with this shoe," he cautioned. "It's important that you understand what the shoe is designed to do, and the farrier must have a good understanding of internal balance and how to adjust the shoe relative to the horse's needs. You have to be able to read the radiographs of that horse and know what you're doing to the internal structures. This shoe is very technique-sensitive; if you get the belly (curve) too far forward, you'll just lock him into standing on his heels. You have to shoe more than the outer hoof wall, you also have to shoe the internal structures."

He also noted that the foot must stay dry and tough to help regenerate tissue, as wet, soft horn is much more vulnerable to compression and compaction. A positive pressure frog plate will help re-establish the crushed digital cushion, he added.

White line disease Redden noted that this shoe helps decrease stress in the hoof wall at the toe. This is important with white line disease, as mechanical stress allows hoof wall separation and opportunistic bacteria invade the area to cause the disease. Reducing wall stress stops the separation from progressing further, and allows healthy horn to grow out and replace the diseased tissue.

Chronic laminitis He uses this shoe often for chronic cases (acute cases are treated with his Ultimate shoes, he noted). "The goal is to help the horse shift load to the heel and away from the apex of the coffin bone in order to grow more sole depth," he explained.

Full-thickness toe cracks The decreased stress on the toe and increased growth with this shoe are very helpful on these cases. "The majority of feet treated have 10-15 mm of sole growth and one-half to three-fourths inch of new horn growth above the crack within 30-45 days," he reported.

Fitting the Self-Adjusting Shoe
The key to success with self-adjusting palmar angles is to find what angle the horse likes, and make it easy for him to stand there. Not just any curved shoe will do. "The degree of convexity or rocker will depend on the predetermined goals with the case, the problem you wish to solve, the mass of hoof present (sole depth and horn quality), and the palmar angle," Redden explained.

"You have to plan this with radiographs so you have an idea of what you're doing to the palmar angle," he advised. "That will allow you to talk about the intensity of the shoe. For someone to just talk about raising the heels, it's like pointing a gun at your feet and telling you to jump. �How high?� you'd ask. Identify the soft tissue parameters so you know what you've done.

"Plan your work on the film; draw on the film what you want to accomplish mechanically," he recommended. "Put in two nails and radiograph the foot again to see if you've done what you thought. Don't put six nails in and then check it, because you probably won't pull it if you don't like what you see."

He showed a radiograph of a horse standing in one of these shoes, describing the case as follows: "This horse has a lot of heel pain. How do I know that? He's using every inch of this rocker, standing all the way on his toe. If they're happy in the middle, you'll see air under the front and the back of the shoe. Until I can find the place where they've got a little air under the heel and toe, I'll pull it back off and put a little more belly in it, because he's telling me he wants a little more."

He noted that he likes to see a tiny bit of daylight between the center of the toe and the shoe. "You want to be able to slip a business card in there�this is very important, because otherwise your sole is a little convex (curved outward and hitting the shoe) and you can really sting them," he said.

He places the highest point of the curve at or slightly behind the widest point of the foot, and he notes that the curve must be softened at the heels to avoid bruising the heels with the end of the shoe. Since the foot is trimmed flat, the quarters will not touch the shoe; if the gap is large (more than 4 mm), he fills the space with hoof repair composite to improve foot/shoe contact.

Take-Home Message
"This shoe concept has been very beneficial for cases that have problems associated with less-than-optimum foot mass, as it consistently accelerates sole and horn growth, enhancing the protective function of the hoof capsule," Redden concluded.

About the Author

Christy M. West

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.

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