Photo: The Horse Staff

A horse with slightly asymmetrical feet is nothing out of the ordinary. But if one hoof differs dramatically from the other, you might be dealing with a club foot—an abnormally upright hoof with long, contracted heels and a prominent or bulging coronary band. Because shortening of the musculotendinous unit (the deep digital flexor muscle and tendon) causes this syndrome, it is more accurate to describe a club foot as a "flexural deformity" of the coffin joint. And while a deformity might sound like a career-ending flaw, with proper management affected horses can lead very comfortable and even athletic lives. 

In this article we will discuss two classes of club foot: congenital, or present at birth, and acquired, or developed over time.

What is a Club Foot? 

To best manage a club foot, it helps to first understand the anatomical structures contributing to the problem. Originating from three muscle bellies on the forearm, the deep digital flexor tendon (DDFT) runs down the back of the limb to insert on the back of the coffin bone. The strong inferior check ligament (IFCL) originates in the carpus (front knee) region and attaches to the DDFT at the middle back of the cannon bone. Any excessive pull (shortening of the musculotendinous unit) on the deep digital flexor muscle and tendon unit causes a complementary pull or flexion of the coffin joint. 

Veterinarians diagnose congenital flexural deformities in neonates unable to fully extend their lower limb joints. The degree of this deformity can range from a mild outward buckling of the hoof to one so severe that the foal cannot touch his heel to the ground. 

An acquired flexural deformity develops when the foal is 2 to 8 months of age—typically by 12 weeks. Causes might include genetics, diet (excess energy and/or mineral imbalances), excessive exercise, and/or a withdrawal response to pain such as occurs with physitis (inflammation of a bone’s growth plate) or trauma. A foal with an acquired flexural deformity might show excess toe wear initially and, as the deformity progresses, the coronary band might appear to bulge more as the foot becomes increasingly upright. Over time the hoof wall becomes dished and the foal has greater difficulty touching his heel to the ground. If not corrected early, the horse will retain a club foot as he matures.

Veterinarians can classify both congenital and acquired club feet as Type 1 (hoof-ground angle is 90 degrees or less) or Type 2 (hoof-ground angle is greater than 90 degrees). Or they can use a grading system ranging from Grade 1—a mildly upright hoof with a hoof angle 3-5 degrees steeper than the opposite foot—to the most severe Grade 4, in which the hoof is severely dished, the coronary band is as high at the heel as it is at the toe, the hoof-ground angle is 80 degrees or greater, and there are pronounced changes to the coffin bone.

A foal with a mild deformity that is responding to treatment can be given limited exercise.

Dr. Randy Eggleston

Detecting Club Feet in Foals

Many veterinarians believe growth rate—either a disproportionate rate of bone and tendon/ligament growth or pain associated with rapid bone growth—plays a part in acquired flexural deformity development. Randy Eggleston, DVM, Dipl. ACVS, clinical associate professor of large animal surgery at the University of Georgia’s College of Veterinary Medicine, says these deformities can occur fairly quickly, usually in rapidly growing foals nursing heavily lactating mares. Foals generally experience the most rapid growth from 30 days to one year. This is when owners should be on highest alert for deformity development, he notes. 

"However," he adds, "it can occur at any time, particularly subsequent to anything causing chronic lameness or pain that stimulates the foal to load one limb differently from the other. Early on an owner might notice that the front of the hoof wall begins to look more upright. It helps to compare both feet since it is less common for an acquired flexural deformity to occur in both limbs." 

As a preventive measure, Eggleston recommends formulating a foal diet that ensures slow but even growth. Reduce the energy content (e.g., high starch and sugar cereal grains) of the mare’s and/or foal’s diet, eliminate unnecessary supplements, and feed good-quality grass hay (rather than alfalfa). Specially formulated commercial products can also provide well-balanced energy and mineral nutrition appropriate for various age groups.  

Impact on Soundness

A club foot alters a horse’s hoof biomechanics, frequently leading to secondary lamenesses. Affected horses tend to land toe-first, and their heel’s growth rate is amplified relative to the toe’s, causing hoof capsule distortion, the hoof wall dishing described, and ridges. 

The frog often recedes as the heels contract, leading to increased impact stress throughout the hoof as the soft-tissue structures in the rear of the foot absorb less energy. "In conjunction with the overlying digital cushion, the frog normally functions to absorb concussion during the stance phase as the horse loads the limb," explains Harry Werner, VMD, of Werner Equine, in North Granby, Connecticut. "As the frog recedes, impact shifts from the frog to the hoof wall and on to the coffin bone." 

Eggleston says excess loading on the dorsal (front) aspect of the foot combined with increased heel growth results in a thin sole at the toe, which tends to bruise. "There may be visible remodeling or fragmentation at the tip of the coffin bone seen with imaging," he adds. 

Older horses with club feet frequently suffer from lameness issues due to such thin soles and bruising, along with hoof cracks, white line separation, laminar inflammation, and abnormal coffin joint loading and strain on the navicular bone’s supporting ligaments. "Because contracture or shortening of the DDFT is the primary problem, increased stress on the flexor cortex of the navicular bone (where the DDFT attaches to the bottom of the tiny bone) has the potential to elicit early onset changes to the navicular bone," Eggleston notes. 

Managing Foals

When caring for the young foal with a congenital flexural deformity, Eggleston says veterinarians commonly administer the intravenous antibiotic oxytetracycline, which is known to stimulate tendon laxity. "It is not uncommon to give two to three treatments," he explains. "I like to treat every other or every third day to monitor the response from the previous dose. While not a common problem, oxytetracycline can be harmful to the kidneys at the dose used for flexural deformities. Kidney function may be monitored through blood creatinine (a waste byproduct of muscle metabolism eliminated via the horse’s kidneys) before and after treatment." 

Bandaging can also cause the soft tissue in the affected limb to relax. "The more immobilization applied to a limb, the more laxity is achieved to help a club-footed foal," Eggleston says. "To protect a foal’s sensitive skin, the bandage should be well-padded with pressure applied evenly and reset daily or every other day."   

The amount of exercise club-footed foals can complete depends on the deformity’s severity. "A foal with a mild deformity that is responding to treatment can be given limited exercise," Eggleston suggests. 

If foals develop flexural deformities over time, Eggleston encourages owners to have experienced farriers trim the animals’ heels every two to three weeks to counter the accelerated heel growth seen with this condition. "Some advocate using toe extensions or elevating the toe to achieve more stretch in the soft tissues in the back of the leg while some do not," he says. "It’s best to determine the approach on a case-by-case basis." 

He does stress that managing these foals is not a case of "‘If a little will do, then more will be better.’ Being too aggressive at the toe can cause lameness and more damage to the soft tissues of the toe."

For cases that don’t respond to therapeutic farriery, Eggleston says an inferior check ligament desmotomy (a surgical procedure in which the veterinarian transects the ligament) might be successful, as removing tension from this strong band allows the DDFT to stretch. This is best done within four weeks of detecting the club foot.

Foals with club feet have a good prognosis for reaching their intended purpose if veterinarians perform this surgery on animals younger than 8-12 months of age, he says. "Good results have also been achieved in yearlings and also in select cases of mature horses." 

Eggleston explains that the first four to six weeks post-desmotomy are the most critical for healing. Over the following months the ligament scars and strengthens. 

"The key to treating a foal with a flexural deformity is to treat aggressively, monitor the foal’s progress closely, and use a combination treatment approach (e.g., surgery and therapeutic farriery)," he says. "There is a fine line between treating too aggressively and making the foal uncomfortable, and not being aggressive enough."

Managing Mature Horses

Werner has decades of experience caring for performance and sport horses, and he is well aware that sound feet are a prerequisite for athletic excellence. For the mature horse, he stresses, "Radiographs (X rays) are essential to determine the degree of deep digital flexural deformity and to examine the foot for other concurrent pathology (disease)."  

Werner recommends resolving an adult horse’s club foot as much as possible through therapeutic farriery and trimming at four-week intervals, rather than observing the more common six-week interval. "If the foot is allowed to overgrow," Eggleston warns, "the goals of therapy become futile."

Often, less is more: "Rather than attempting to make dramatic changes, I recommend lowering the heels from the frog apex toward the rear of the foot and to enhance breakover (ease of lifting the foot off the ground as the foot rotates at the toe) by rolling the toe," Werner says. "The goal is to engage all of the sole in weight-bearing to alleviate abnormal biomechanical forces on the front of the foot."

Eggleston offers similar recommendations, adding, "As the heels are lowered, observe the horse both standing and at the walk to evaluate comfort level and foot landing, which should be flat-footed rather than toe-first. To help relieve tension in the flexor tendons, a short wedge shoe or pad may be added." 

Werner says your veterinarian might also recommend judicious intra-articular corticosteroid and hyaluronate injections to help relieve associated coffin joint pain. 

He has reservations, however, about the ability of mature horses with even mild club foot to perform well, despite treatment attempts: "Many will exhibit ‘poor performance’ if not outright lameness," he says. "When examining a horse for prepurchase, I always advise a buyer to consider a club foot as a risk factor for future lameness. Limitations on performance depend on the degree of flexural deformity as well as on any concurrent lameness and the proposed performance discipline." 

If owners have club-footed horses in training or competition, Werner urges them to alert their veterinarians to subtle or overt evidence of poor performance or lameness. These horses tend to develop heel pain and foot lameness earlier than horses with normal feet, says Eggleston, but good, consistent hoof care can reduce complications.

Some cases are challenging to manage no matter the veterinarian and farrier’s effort. Werner recommends performing an IFCL desmotomy on mature horses with severe flexural deformities not relieved by appropriate therapeutic farriery (provided there is no accompanying degenerative joint disease or chronic lameness). In these cases, Werner says, "therapeutic farriery begins at surgery and continues well beyond four weeks. In fact, if resolution of the deformity is not complete, therapeutic farriery is indicated for life." 

Take-Home Message

A club foot can have significant repercussions on a horse’s performance success and athletic longevity. Prompt recognition and diligent farrier care allow the horse with a flexural deformity to be as comfortable as possible. "There is usually a reason for a horse to have mismatched feet, whether it be due to conformation, lameness, foot disease, or poor foot care," Eggleston says. 

Both Eggleston and Werner urge attending farriers and veterinarians to have strong working relationships with one another, and they recommend trimming and shoeing every four to five weeks. Early intervention is important to avoid a flexural deformity persisting into a horse’s mature athletic years.