Horse Health, Abscess Distress
By: Rebecca Colnar

My first experience with hoof abscess came a few days after I bought my thoroughbred mare at the track. I went to the barn one morning to find her dead lame, unable to place any weight on her back hoof. I feared the worst. Did she possibly have an existing injury I wasn't told about?

Instead, my vet said her acute lameness was a hoof abscess.

After this happened a couple of other times with her, I could diagnose the problem on my own. She'd be very lame for a day or two, then she'd be fine, and she wouldn't go lame again for another year.

Veterinarian Steve O'Grady of Virginia Equine Podiatry Center, confirmed what I had learned the hard way: hoof abscess is a common cause of acute lameness.

Abscesses occur when foreign matter, commonly called "gravel," gains entry into the hoof through the sole-wall junction, or white line, explains O'Grady.

"The debris will migrate in the hoof to the laminae, the sensitive tissue above the horse's sole, leading to an infection. The other common cause of subsolar abscess is penetration of the bottom of the foot--usually the sole or frog--by a sharp object." O'Grady adds that infection may also gain entry into the foot via a hoof-wall crack.

An untreated abscess will follow the path of least resistance up the hoof wall.

"Mechanical breaks or weakness in the white line can happen with improper trimming (leading to hoof imbalance), hoof-wall separations, aggressive removal of the sole during trimming, and chronic laminitis," the veterinarian explains.  An untreated abscess will follow the path of least resistance up the hoof wall and will form a draining tract at the coronet.

Most affected horses show sudden lameness, O'Grady says. "The degree varies from subtle to non-weight bearing. The pulse at the fetlock is usually pounding, and the foot with the abscess will be warmer than the opposite foot."

The point of pain can be located using hoof testers. The wound or point of entry may not always be visible since some areas of the foot, such as the white line and frog, are somewhat elastic, and wounds in these areas typically close.

"Sometimes pain will be noted over the entire foot. In this case the veterinarian may want to check for a severe bruise or a possible fracture of the coffin bone," he notes.

Treatments work best at the first sign of lameness, before the gravel ruptures at the coronet. Treat a simple subsolar abscess by opening and draining the infection. The opening should be large enough to allow drainage, but not so extensive as to create
further problems.

Drainage can be speeded using a poultice for the first 48 hours. "This often eliminates the need for continued foot soaking," O'Grady advises. "The hoof is kept bandaged with a suitable antiseptic until all drainage has ceased and the wound has closed.

At this point, a small gauze plug, held in place with glue, is used to fill the opening. This keeps affected areas clean and prevents the accumulation of debris in the wound." The shoe can be replaced at this point.

If the pain can be located, but drainage cannot be established at the white line, then the infection has migrated under the sole away from the white line.

"Under no circumstances should an opening be created in the sole. This will lead to a persistent, non-healing wound and more susceptibility to bone infection," O'Grady cautions.Instead, expect your vet to make a small channel in the subsolar tissue leading to the infection.

Antibiotics are optional and based on the needs of the individual horse. Your veterinarian may prescribe bute or some other medication to ease the discomfort. "Your horse's tetanus immunization should be up to date," O'Grady notes.

Wrapping it up
Although abscesses sound like an equine hoof problem that "just happens," they can be prevented, insists Dr. Steve O'Grady. "A strong, solid white line which resists penetration by debris is the best prevention," he says.

Farriery is a prime factor. "The hoof has a natural ability to provide protection to the sole of the hoof. Enhance these strong features through proper trimming," the vet insists. "Excessive removal of the protective horn is a common practice when too much emphasis is placed on eye appeal instead of functional strength--not a good idea."

To prevent gravel, it is important for the foot to be trimmed to preserve a strong healthy foot. Improperly trimmed feet can lead to cracks and hoof wall separations--one of the most common causes of hoof abscess.

Preventive maintenance in dry weather includes a hoof dressing painted on the entire foot to contain moisture.  Too much moisture can also make a horse susceptible to hoof abscesses. In extremely wet weather or when the horse is being washed frequently during show season, consider hoof hardeners, such as Keratix. Bedding on shavings or sawdust can also help.