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Veterinary Topics: Nineteen feet problems

Posted: Saturday, April 12, 2003

Review of conditions that back up old saying "No hoof, no horse"

SO MANY THINGS can happen to horses' feet, it is amazing there are any sound horses. Here is a look at hoof problems, their diagnoses, and treatments.

Abscess

This is undoubtedly the main cause of foot lameness. The onset is acute; the animal will not bear weight on the affected foot. The cause is often a nail puncture that occurs during shoeing, but an abscess can result from any penetrating lesion of the foot. The ugliest one I have ever seen resulted from a fencing nail that penetrated two inches through the sole of a broodmare's foot.

If caught early enough, the abscess may be opened and drained; otherwise, the pus will migrate upward, erupting at the coronet. This is termed a gravel. If the abscess is not caught early, the entire sole may be undermined. The key to treatment is drainage and the foot should be soaked in a disinfectant and then bandaged. A tetanus booster is essential.

Crack

This is a problem primarily of dry hooves, although it can result from trauma. In dry conditions, it is a good idea to apply hoof dressing to prevent drying.

A crack that does not penetrate to the sensitive areas of the foot does not cause lameness. It should be attended to, however, because it may eventually extend to the coronet. A horizontal groove rasped at the upper end of the crack may be all that is necessary to prevent the crack from going higher.

If there is lameness, applying acrylic hoof repair and administering antibiotics could be necessary. If the problem is a quarter crack, removing part of the hoof wall behind the crack can be done to prevent the horse from bearing weight in that area. A bar shoe is helpful, too. The prognosis is good.

Pastern dermatitis

Occurring usually in horses kept in wet areas, this common condition of the skin of the pastern at the heel occasionally extends to the fetlock.

Lameness is rarely involved, but there is an exudate and crusting and the skin is sensitive to the touch. Treatment consists of gently removing the crust, applying Panalog, an antifungal, antibacterial cream, and removing the horse from the wet conditions.

If untreated, the problem can develop into a thickened, lumpy condition referred to as "grapes," which must be surgically excised.

Navicular syndrome

Some people believe all Thoroughbreds have navicular syndrome. This is not true, but the syndrome is the main cause of chronic lameness in pleasure horses.

This condition is a tough one. A horse may show signs of navicular syndrome and have no radiographic changes in the navicular bone, while another may have radiographic signs but not be lame. A typical navicular syndrome horse is at least seven years old with a chronic, mild forelimb lameness. Usually, there is no response to hoof testers, but pain will usually be shown on flexion of the fetlock. A palmar digital nerve block is considered to be diagnostic.

The most effective treatment is oral isoxuprine and therapeutic shoeing. The prognosis is fair to good for continued use of the horse.

Navicular bursa infection

Navicular bursa lies between the deep digital flexor tendon and the navicular bone. Infection can result from an object that has penetrated through the middle of the frog. A severe nonweight-bearing lameness is difficult to treat.

Treatment consists of removing a section of the frog and deep digital flexor tendon to allow drainage. This must be done within ten days or improvement may be only slight. The prognosis is only fair.

Navicular bone fracture

This is an uncommon, acute lameness in which a horse will not put weight on his heel. Diagnosis is by X ray. Stall rest may allow healing, and a surgical technique that sounds difficult has been described. The prognosis is poor.

Thrush

This is an infection of the sulci of the frog, usually resulting from a horse being stabled in moist conditions. There is a foul-smelling exudate, but lameness only occurs in longstanding cases. Treatment consists of cleaning the sulci and removing necrotic tissue. Antibiotics may be necessary in severe cases. The prognosis is good.

Laminitis (founder)

In school, Dr. Hoffman told us, "There are two kinds of ponies: Those that have foundered and those that will." Amen, but the disease can occur in any horse.

In laminitis, there is a separation of the hoof wall from the underlying sensitive laminae due to necrosis of the laminae. The disease can occur in all four feet but is much more common in the forefeet. Horses are reluctant to move and they stand with their front feet extended to relieve pressure. The coffin bone may drop, with the front of the bone extending through the sole.

Common causes are overeating of grain, grazing lush pasture, drinking too much water when hot, a retained placenta and accompanying metritis, and systemic bacterial infection. In the first three causes, treatment consists of giving mineral oil to slow absorption of ingested material and help move it out. In the last two, appropriate antibiotic therapy is indicated. With all causes, nonsteroidal anti-inflammatory drugs (NSAIDs) should be given for two to four weeks.

If caught early, the prognosis is fair to good. The longer the disease goes without treatment, the worse the prognosis becomes.

Seedy toe

This is separation of the hoof wall from the sensitive laminae in the toe region. It is almost always a sequel to founder. Infection can enter the separation and cause lameness; in the absence of infection, there is no lameness. Keeping the separated area free of dirt and other matter is the only treatment.

Sidebone

This is calcification of the lateral cartilages, or cartilages of the distal phalanx, of the hoof. It is a condition of older horses and usually does not cause lameness but is considered a type of unsoundness. If lameness is present, it is due to fracture of the calcified cartilage. Six to eight months of stall rest is the treatment if there is lameness.

Corns

This condition is questionably named because it bears no resemblance to corns in people. Rather, it is a subsolar hematoma between the sensitive and insensitive layers of the hoof, usually occurring at the heel between the bars and the wall. The common cause is improper shoeing; the heel of the shoe rests on the sole, producing pressure where pressure was not intended.

Corns are usually seen as a chronic, mild lameness, but they may not produce lameness at all. If the pain is great, the sole should be opened over the corn to release pressure. Once the cause is removed, the prognosis is good.

Fracture of the coffin bone (third phalanx)

This is primarily an injury of athletic horses. I have been told it is more common in Standardbreds than in Thoroughbreds.

The usual initial sign is acute lameness after a work or a race, with the horse reluctant or refusing to bear weight on the injured limb. Treatment consists of applying a bar shoe with clips or a ridge shoe, as well as time and stall rest. I have seen one horse heal in about four months, but the usual time is six months or more.

The prognosis is usually good. There is also a surgical procedure in which a screw is placed in the bone.

Fracture of the extensor process of the coffin bone

This condition is confusing. There may be an acute lameness following exercise; there may be a chronic mild lameness; or there may be no lameness at all. Sometimes the fracture is just an incidental finding on a radiographic exam. To be sure a fracture is the cause of lameness, a diagnostic nerve block should be used.

Small fractures may be removed arthroscopically, while large ones have to be repaired with the insertion of screws. The prognosis is good.

Canker

This rare condition probably occurs more often in the hind feet. Lameness does not occur until the canker is far along and treatment is long and difficult. There is usually a history of the horse receiving poor or no foot care.

The frog is undermined and there is a foul smell to the foot. Affected areas must be thoroughly debrided and the foot soaked in a disinfectant. The foot should be wrapped with a disinfectant applied and the wrap should be changed daily for at least one week, then changed three or four times a week thereafter until healing is complete--which may never happen. The prognosis is guarded at best.

Coronitis

This uncommon condition is an inflammation of the coronary band, which might be seen in febrile illnesses and is occasionally seen with founder. The only case I ever saw was in a young mule that had to be euthanized.

There is a sudden onset of acute, severe lameness with reluctance or refusal from the horse to bear weight. All four feet may be involved. Swelling appears around the coronary band and exudate oozes from the area. After one week to ten days, the hoof wall separates from the coronary band and the hoof is sloughed. This is what happened to the mule.

There is really no treatment that helps and the prognosis is poor. In cases that resolve, the coronary band is affected and the hoof exhibits abnormal growth.

Osteitis of the coffin bone

This is an inflammation of the sensitive structures of the solar areas of the front feet and is usually bilateral. It is fairly common in racehorses and can result from improper shoeing, trimming that puts too much weight on the sole, or from running on hard tracks.

An affected horse does not stretch out during exercise and has a shuffling gait. Hoof testers show pain over the entire sole. Proper shoeing, possibly with pads, and trimming will give relief. NSAIDs and stall rest will usually solve the problem. The prognosis is fair to good.

Clubfoot

The affected foot is misshapen and upright. It is considered an unsoundness, but milder cases may show no gait alteration. Corrective trimming can reduce or eliminate the problem, which will return if trimming is not performed routinely. In young foals, severing the inferior check ligament will solve the problem. Some say a clubfoot is an inheritable condition, but it is not.

Pyramidal disease

This is abnormal growth of the hoof wall in the toe area due to injury, which is usually low ringbone or fracture of the extensor process of the coffin bone. A ridge of thickened hoof wall originates at the coronary band and extends downward. The disease does not cause lameness; if lameness is present, it is due to the condition that has caused the hoof growth.

Quittor

This uncommon infection of the lateral cartilage results from trauma. Often there is no lameness, but a purulent discharge is present in the rear of the lower pastern. Because there is poor blood supply to cartilage, antibiotics are of no use. Treatment consists of surgical excision of the infected cartilage. This review covers what can go wrong with a horse's feet. Next time, we will move higher up the leg.