aluminum heel plate
Heel plate shoes with soft impression material beneath them provides support while loading the hoof structures in a very protected way. | Courtesy Dr. Scott Morrison

Heel problems are common hoof issues in horses, with some estimates attributing more than one-third of all chronic lameness to the heel (caudal) region. The condition owners might be most familiar with is the low heel, which also happens to be one of the most difficult heel problems to manage.

Scott Morrison, DVM, partner and head of the podiatry center at Rood & Riddle Equine Hospital, in Lexington, Kentucky, described the issues low heels can cause and the mechanical tools farriers and veterinarians can use to address them at the 2021 British Equine Veterinary Association Congress, held Sept. 4-7 virtually and in Birmingham, U.K.

Tackle Low Heels Early in Life

Low or underrun heels and long toes are significant because they not only cause hoof problems such as bruised heels and navicular region pain but can also lead to damage further up the limb, including knee injuries, suspensory apparatus failure, deep digital flexor tendinitis, and even back and neck pain, said Morrison.

“As the toe gets longer, it increases the moment arm (torque) about the fetlock joint and coffin joint and increases strain on the many supporting soft tissue structures in back of the foot,” he explained. “Mechanically, it compromises the entire horse.”

Understanding the Heel’s Shock-Absorbing Mechanisms

The heel is extremely important for shock absorption when the horse moves. “It’s normal for horses at speed to land heel-first so the heel can absorb that initial ground contact and dissipate those vibrations generated during ground contact,” Morrison explained.

The foot’s shock-absorbing mechanisms include the digital cushion (the soft tissue beneath the sole that separates the frog and heel bulb from the underlying tendons and bones) and the collateral cartilages on either side of the coffin bone.

“As the horse’s heel hits the ground, those external vibrations are transmitted from the bars in the heel region of the hoof capsule to the collateral cartilages, which house an abundant vascular supply,” he said. “The thought is these external vibrations contribute to movement of blood within the collateral cartilages, essentially acting as a hydraulic shock-absorbing mechanism.”

For this mechanism to function, the horse must have proper structure and form in the back half of the foot. To transmit shock up the leg appropriately, the bars (the folds of the wall on either side of the frog) and buttress (back part) of the heel must be in proper position, said Morrison, lined up beneath the collateral cartilages.

When presented with a horse with underrun heels, he said his goal is to trim the heels back to realign that shock-absorbing mechanism. “That can be a catch-22 because you don’t want to lower the angle of horses foot,” he noted, but “overall, spatial arrangement of the structures on the bottom of foot is more important than angle. We can always help the angle with shoeing modifications.”

Managing low heels is most effective when done proactively, as early as the first few weeks of life, so the foal can develop proper heel position from the outset.

“Early identification of hoof capsule distortions should be made and addressed as soon as possible, before they lead to injury and dysfunction of the internal structures of foot,” said Morrison.

Tools for Managing Heel Issues

Morrison listed the strategies and shoe types he uses when correcting and managing low heels:

Mimic the bare foot When possible, Morrison likes to pull low-heeled horses’ shoes, especially if they’re laid up or recovering from injury. “If it’s not contraindicated, I try to get some normalcy and integrity back in the heels,” he said. “Horses with dysfunctional heels tend to do better when barefoot.” He acknowledged, however, that not all horses can go barefoot, which can lead to soreness and bruising. In these cases he reaches for frog support.

Heart bar shoes These shoes provide heel support and can take various forms: long, short, recessed, steel, aluminum, and more. Morrison also likes using stabilizer plates, which are heart bars with two branches welded in to prevent the tip of the frog support plate from bending.

Frog support Horses with heel issues often develop abnormal frogs as a result. “When the heel starts to fail and collapse, the frog starts to prolapse,” said Morrison. “That is a telltale sign the frog needs support.”

For this reason, heart bar and other shoe types often have material in contact with the frog. The material Morrison chooses depends on the horse. “A metal bar can be too firm on, say, a jumper landing from a jump,” he said. “A thermoplastic plate is more forgiving. Play around with different types of frog support.”

Rolling the heel Rolling or rockering the heel branch of the shoe can also help horses with weak or underrun heels. “This allows us to trim the heels back to the widest part of the frog without invading sole depth,” Morrison said. “It gives horses a nice landing zone that might not create as much concussion.”

Not trimming flat With really low-heeled feet, Morrison said he uses different planes of trims to leave as much sole depth as possible under the wings of the coffin bone.

thermoplastic heel plate
A thermoplastic heel plate can be more forgiving against the horse’s frog than metal. | Courtesy Dr. Scott Morrison

Roller motion shoes For horses with little foot surface to trim, he likes to use a roller motion shoe to ease breakover (the moment the heel leaves the ground during movement) and take stress off the heel.

Heel plate shoes Applying heel plate shoes with soft impression material beneath them provides support while loading the hoof structures in a very protected way, said Morrison. “I find I’m able to rehabilitate really compromised heels effectively with this type of shoe.”

Take-Home Message

Correct foot shape and balance are paramount to maintaining soundness and optimal performance, said Morrison. The goal when restoring heel distortions is to correct the alignment of the bars and collateral cartilages so they can absorb shock, dissipate vibrations, and support the horse’s weight effectively. Farriers and veterinarians have many options for achieving this, and the ideal one depends on the horse, its job, and its needs.