Probably the most common cause of acute lameness in horses, hoof abscesses can appear without warning. One day your horse is sound, the next she’s crippled, but there’s no apparent injury. The likely cause is a hoof abscess, a pimple-like infection. Abscesses are most often caused by the entrance of bacteria into the hoof through penetrating wounds, hoof cracks, and even “close” horseshoeing nails, but a wider variety of issues — anything that weakens the integrity between the sole and hoof wall makes it easier for bacteria to invade or that causes internal injuries — can contribute to the development of an abscess. These additional potential factors include the cycling between wet and dry environmental conditions, poor hoof conformation or balance, ground conditions, bruising (the hemorrhaging area is conducive to bacterial reproduction), hot-fitting a shoe on a very thin sole, hoof wall defects, digital instability and systemic infections.
Hoof abscesses cause pain through a buildup of pressure associated with the accumulation of pus from the infection and the fact that the hoof wall is rigid and cannot expand to relieve the pressure. While some may prefer to allow the abscess to rupture on its own, it is best to treat the abscess, get it drained and prevent further contamination with additional treatment that may include antibiotics, anti-inflammatory medications, antiseptic solutions, poultices and soak bandages. The most important aspect of the treatment is establishing appropriate drainage. To do this, we will often try to locate the entry wound and then create drainage through the sole so gravity is on our side and will assist with drawing out the pus. Left untreated, the infection associated with the abscess can travel up the hoof wall and destroy sensitive structures within your horse’s hoof. The resulting damage can lead to more permanent lameness. With proper treatment, progressive improvement should be observed on a daily basis. If such improvement is not observed, additional diagnostics may be necessary to determine the true cause of your horse’s infection and resulting lameness.
Prognosis following treatment depends on the tissues involved and the severity of the infection. Those infections that have remained largely superficial have a much better prognosis than those that have been allowed to involve other structures such as the coffin or navicular bone, navicular bursa, coffin joint, collateral cartilages or tendon sheath.
It may not be possible to prevent all abscesses, but good hoof care will go a long way toward that end. Good hoof care should develop a snug and uniform junction at the sole wall while leaving adequate sole for protection. Routine farrier care and frequent hoof cleaning to remove rocks and debris are also important preventive measures. Being proactive will help protect the soundness of your horse and avoid the pain associated with abscesses.