Subsolar abscesses, localized infections just beneath the sole of the hoof, are one of the most widespread causes of foot pain. As an abscess develops, it exerts pressure on the sensitive structures of the foot. Because the hard hoof wall does not expand, this pressure can become extremely painful.
Horses with abscesses may show varying signs of lameness, but it is often an acute onset of a significant degree of pain, sometimes as severe as Grade 5 lameness (see “Lameness Scale”). These horses may have heat in the foot and an increased digital pulse felt at the fetlock or pastern.
Diagnosis of a hoof abscess is typically straightforward, and identification of the precise location is usually easily achieved with hoof testers. Occasionally radiographs are required to pinpoint the location of the abscess and the extent of its damage, as large or chronic abscesses may infect the coffin bone.
Treatment involves relieving the pressure by draining the abscess. Using a hoof knife, your veterinarian can carefully pare down the sole until the pus can escape. If the sole is too hard, then the foot can be soaked in warm water and Epsom salts for several days to soften the area. Abscesses may also break out through the coronary band, taking the path of least resistance. This area should be monitored closely in these cases.
There are many factors that contribute to the development of hoof abscesses, such as an environmental shift from wet to dry footing; hard ground that bruises the sole; dirty, wet stalls; improper shoeing; or poor hoof conformation. Prevention involves keeping horses in clean conditions and performing routine hoof care, such as daily cleaning and regular trimming.