Hoof Abscesses

A hoof abscess is one of the most common causes of lameness in horses. It occurs swiftly and usually needlessly--a nail or sharp piece of wire or metal is left lying about, an unlucky horse steps on the object, penetration occurs, and is followed by acute lameness and infection.

Since most of us have had our own similar, barefoot encounters with a stone, nail, piece of glass, or piece of wood, it's not hard recalling the pain of even a fairly superficial penetration, one that we humans usually treat quickly and effectively. Our equine partners, however, are not always as lucky; it sometimes takes time before the accident is discovered, an accurate diagnosis is made, and treatment is initiated. Should the wound form an abscess where pus forms at the injury site and infection takes hold, the best-case scenario is a couple of weeks for a full recovery. The worst-case scenario is another matter: If the penetration is deep enough and involves internal structures, recovery could take much longer or be so limited that the horse is left severely and chronically lame and euthanasia is the only humane option.

An abscess also can be caused by sole bruising, a horse being trimmed too short, or wet conditions followed by dry conditions.

A hoof abscess is definitely serious business.


George Martin, DVM, MS, MBA, Dipl. ACVS, professor of veterinary surgery, section chief of equine medicine and surgery, Louisiana State University, describes a hoof abscess as a "bacterial infection in the sensitive structures of the horse's hoof." The cause almost always is the result of a sharp object penetrating the hoof. Occasionally, a hoof abscess occurs due to a seedy toe. Explains Gayle Trotter, DVM, MS, professor of surgery, Colorado State University, "The white line region of the foot gets separated enough that dirt migrates up along those tissue lines. This can lead to an abscess in some of the deeper structures."

Clinical signs of a hoof abscess include sudden, extreme lameness and pain so intense that horse owners sometimes mistake the condition for a broken leg. Other signs include a hoof wall that is hot to the touch, an increased digital pulse, and, if the condition progresses, the breaking out of the abscess at the coronary band or bulb of the heel.

Usually it's not obvious that a puncture wound has occurred, as the wound generally is quite small. "To make a diagnosis," Trotter says, "the veterinarian relies on the history of the acute onset (which usually means the horse has an infection somewhere or a broken leg), the fact that this condition is quite common, increased heat to the hoof, and the pounding pulse in the hoof."

In addition, hoof tester pressure over a portion or all of the sole or frog region will produce a painful response, Martin says. "Sometimes radiographs are needed," Martin continues, "but not usually for acute, simple foot abscesses. Radiographs, however, provide essential information in complicated cases by providing baseline information about the condition of the coffin bone."

The more challenging part of the diagnosis is locating the actual wound, a necessity in order to commence treatment. "We're looking for this very, very small, black, discolored dot where the foreign body penetrated," explains Trotter. "When we find it, we keep following it until it either disappears or leads us down to the abscess. If the penetration occurs over the sole of the foot, usually we can start paring down gently with a sharp hoof knife.

"The harder ones to find are when they're in the frog, where it's even more difficult to locate that small, discolored area. Often in those cases, we can't find the tract. Even worse, if that penetration is very deep, it can go right up and penetrate into the navicular bursa region, which is a lot more serious than if it just penetrates the sole. The veterinarian has to determine whether it has penetrated into the navicular bone region or whether it involves the tendon sheath near the back of the foot or the coffin joint."

To do so, the veterinarian might use contrast studies. "We take a dye that can be seen as white on radiographs and inject it either into the bursa, coffin joint, or tendon sheath," says Trotter. "This allows us tosee if the contrast agent leaks out into the site where there's been a penetration by the foreign body. Seeing a small amount of leakage helps tell us that structure is involved."

Occasionally, the penetrating object remains embedded in the wound. "If a veterinarian can get to the patient in a reasonably short period of time," says Martin, "the object should be left in place rather than pulled out immediately. When left in place, the veterinarian can radiograph the foot with the object in it to determine the depth of penetration. This information is critically valuable to decide whether very aggressive therapy should be started initially or whether it is safe to use standard drainage methods."

Treatment & Prognosis

The fundamental concept of treatment for an abscess in the sole, Martin says, begins by draining the abscess through the bottom of the foot, usually by removing the sole over the abscess. "Next is to prevent contamination into the area with a good bandage and water-impervious boot. Sometimes we give antimicrobials by injection or by mouth for seven to 10 days." Healing of the superficial or outer sole tissues generally takes a few weeks.

Treatment needs to be more aggressive if the abscess occurs in deeper tissues. "At the least, the horse should be anesthetized and the puncture opened and lavaged," Martin says. "Often this type of injury requires removing a large segment of the frog, digital cushion, and deep digital flexor tendon."

"This is obviously a quite serious procedure and fairly invasive," Trotter points out. "Even though it's life-saving in some horses, a lot of them end up chronically lame even after we clear the infection."

If a bursa abscess is caught early, the veterinarian might use an arthroscope to help treat the condition. "We can go into the bursa, see where the penetration was, clean up the infected tissue, and flush it with antibiotics," Trotter explains. "We'll also put the horse on systemic antibiotics to try and prevent or control any local infection."

The success of recovery depends on how deep the penetration is; the deeper it goes, the worse the prognosis.

If the abscess is confined to the sole, odds of a full recovery are very good. One publication cited 21 of 22 horses went sound following treatment, Trotter says.

Abscesses in the frog have less chance for a full recovery. "One paper cites that only 14 of 28 horses recovered to any degree of soundness after deep penetration to the frog that did not go all the way into the bursa," Trotter re-ports. "In another paper, where penetration went deeper, all the way into the frog and tendon and into the bursa, only 12 of 38 horses recovered." For horses where an arthroscope was used in treatment, prognosis improved to 13 out of 20 horses going back to full athletic use.


In most situations, hoof abscesses do not have to happen. "Nails and other stable hazards are the number one culprit of hoof abscesses because they cause penetrating injuries to the deep tissues of the foot and carry bacterial contaminants into the tissue," says Martin. "Wet weather seems to promote foot abscess formation."

Clean up the barn and stable area, he advises.

Trotter has similar recommendations. "Try to maintain a clean environment in terms of small, sharp metal objects that the horse could step on. Make sure the area where your horse is shod does not have a lot of horseshoe nails laying around. Watch out for old fencing material where nails could have been buried in the ground. Be very careful that you don't lose hypodermic needles in the environment."

Should a problem occur, seek veterinary attention quickly. "For horses that have an acute onset of lameness, their owners need to get a veterinarian quickly because the success rate is higher the earlier these can be diagnosed and treated," Trotter stresses. "Early diagnosis and fairly aggressive treatment are important for a successful end result."

About the Author

Marcia King

Marcia King is an award-winning freelance writer based in Ohio who specializes in equine, canine, and feline veterinary topics. She's schooled in hunt seat, dressage, and Western pleasure.

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