What It Is

A hoof abscess is a painful infection that occurs when bacteria make their way into the sensitive tissue of the foot, causing a pocket of pus to form and pressure to build within the relatively rigid hoof capsule.

Causes

Bacteria normally present in a horse’s environment or on the surface of the hoof gain access to the sensitive structures within through a variety of routes, which include:

• a puncture wound
• a sole bruise
• a corn (a specific type of bruise that occurs at the back of the sole in the angle between the hoof wall and bars)
• a nail prick from a recent shoeing
• an injured or diseased white line (the soft, fibrous inner layer of the hoof wall)

What’s at Stake

Prompt diagnosis and treatment of a mild abscess will relieve a horse’s pain and restore soundness so he’s able to return to work in a few days to a week. Deep infections require a more extensive course of care and can take weeks to months to heal. Left untreated, a hoof abscess can alter the way the hoof grows or lead to laminitis or an infection and deterioration of bone that will have a lifelong effect.

Signs of Hoof Abscesses

Not all hoof abscesses are exactly alike, but the most common signs include:

• pain and lameness, appearing gradually or suddenly and ranging from mild to so severe that a horse may be reluctant to bear weight on the affected limb; it may look like he has broken a leg
• swelling, perhaps involving the heel bulbs, coronary band and/or pastern and extending to as high as the knee or hock
• heat, detectable by touch, in the hoof wall or limb
• increased digital pulse, which can be felt near the pastern
• a foreign object—a nail, screw, shard of glass, stone, etc.—embedded in the sole. Don’t remove any item you may find. Give your vet the chance to evaluate the location, depth and angle to determine the extent of damage and infection within the hoof and ensure that the entire object is removed so it won’t cause any more trouble.
• tracts in the sole or coronary band draining gray or black pus
• foul odor emanating from the hoof

Diagnosis

A veterinarian will look at the horse’s history and recent activity and do a lameness evaluation. She’ll clean and examine the foot, then use hoof testers to apply pressure to various points on the sole to identify any sensitive spots that could point to the site of the infection. A radiograph may be necessary to reveal the exact location and extent, which will show up as a dark area on the image.

Treatment

Draining the abscess is priority one. Some will break on their own through the coronary band or sole. But that can take time—which means prolonged pain for the horse as the infection continues to grow. Instead, your vet likely will initiate drainage by using a hoof knife to pare out the abscess through the sole. That way, gravity can aid in clearing the pus.

She’ll pack the sole to protect against infection and allow for continued drainage. Products containing iodine, chlorhexidine or ichthammol are commonly used. Then she’ll apply a bandage and often additional protection, such as a hoof boot or treatment plate secured to a shoe. Based on the horse’s needs, she may recommend a nonsteroidal anti-inflammatory medication for pain. In some cases, an antibiotic may also be prescribed. The bandage will need to be changed daily until the drainage stops, the exit hole is dry and the horse shows no sign of lameness.

In cases where the location and depth of an abscess make it difficult to drain, first soak the hoof in a mixture of warm water, Epsom salts and povidone iodine or other antiseptic solution may help to draw the infection closer to the sole for treatment. Some veterinarians may recommend soaking as part of follow-up care. But it’s important to avoid oversoaking, which can weaken and harm the hoof.

Lookout For

Most hoof abscesses resolve without complication. But a horse requires additional veterinary care if he:

• is still experiencing pain two days after treatment
• has lost his appetite
• is noticeably shifting his weight or lying down more than usual

Additional signs of trouble include:

• drainage that persists more than 48 hours after treatment
• proud flesh that grows out of the drain hole

Preventing Hoof Abscesses

To reduce the chances of your horse developing a hoof abscess:

• Keep his environment as sanitary, dry and hazard-free as possible
• Clean hooves daily and examine them closely for signs of injury or trouble brewing, such as bruises and wounds.
• Schedule regular farrier visits to maintain good hoof condition, especially if a horse is genetically predisposed to poor hoof conformation or quality.
• Be mindful of the effects of weather on hooves. Footing that transforms from dry to wet or wet to dry, often with the change of season, can soften the hoof or make it brittle, increasing susceptibility to injury and infection.
• Consider applying a hoof dressing or hardener to improve and protect hoof condition. Your vet and farrier can advise on product selection based on your horse’s specific situation.
• Evaluate your horse’s feed to ensure it is providing adequate nutrition. A supplement may be beneficial. Your veterinarian can offer insights on choosing one with ingredients most likely to benefit your horse.
• Look for an underlying cause if a horse seems especially susceptible to hoof abscesses. For example, pituitary pars intermedia dysfunction can weaken the immune system, increasing vulnerability to infection. 

About Julie Bullock, DVM

Practical Horseman thanks Julie Bullock, DVM, for her technical assistance in the preparation of this article. A 1989 graduate of the Virginia–Maryland Regional College of Veterinary Medicine in Blacksburg, Virginia, Dr. Bullock has an extensive background in sporthorses and a special interest in equine podiatry and lameness. A four-star FEI veterinarian in endurance, she is also an endurance rider and the huntsman with the Glenmore Hunt Club in Staunton, Virginia.

This article was originally published in the Fall 2024 issue of Practical Horseman.