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. 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 Farrier 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.
The navicular bone is a small canoe-shaped bone that lies within the hoof behind the coffin and short pastern bones. Affected horses often have an abnormal hoof-pastern angle. While many other injuries affect only one leg, navicular horses tend to be lame in both front limbs. When walking and trotting, they will land toe first. This may temporarily relieve the pain as the horse moves, but it actually increases the strain on the navicular bone and can worsen the disease. During a lameness exam, the gait abnormality will worsen when the horse is trotted in a circle and will dramatically improve after the heel and sole are numbed using a palmar digital nerve block. Horses with a history of heavy work from an early age are at risk of developing navicular syndrome. In addition, breeds such as Quarter Horses, Thoroughbreds and warmbloods are often affected.
Once the lameness is localized to the back of the heel, radiographs should be taken to investigate the area. Radiographs will often show evidence of inflammation and navicular bone pathology, including roughening of the surface of the bone where the tendons and ligaments attach, as well as changes in the internal structure of the bone.
Treatment of navicular syndrome involves therapeutic shoeing to raise the heel, improving the hoof-pastern angle, and shortening the toe to relieve some of the pressure exerted on the bone by the flexor tendons. Anti-inflammatories are another important component, as they relieve pain and help the horse move with more normal hoof placement, limiting the strain placed on the bone. Local anti-inflammatory therapy includes corticosteroid injection into the navicular bursa and sometimes the coffin joint