We are getting into the deep depths of winter, and the influence of both cold and constant moisture can have some detrimental effects on your horse’s feet. One of the most common issues we see is a sole or hoof abscess. A hoof abscess is a localized bacterial infection in the sensitive structures of the hoof. Pus accumulates between the keratinized and germinal layers of the hoof wall. Since the hoof cannot expand, the increased pressure of pus collecting within the hoof capsule causes significant pain. The pus will take the path of least resistance to relieve the pressure and if left untreated, will usually work its way up the hoof wall, breaking out at the coronary band or the bulbs of the heel.
Muddy ground can soften feet and can decrease the sole’s ability to absorb concussion, causing bruising of the main structures. Bruises may abscess if bacteria are introduced through the crack or from circulating bacteria in the bloodstream. Penetrating wounds can occur as a result of a horse stepping on a sharp object such as a rock or nail. These may cause a perforation of the sole that packs up or seals over, and an abscess results as a result of contamination. Occasionally a misplaced nail will also result in a foot abscess.
Foot abscesses are commonly seen around the white line area where foreign bodies such as grit penetrate the white line, allowing bacteria to enter the foot.
Signs of an Abscess
Most affected horses show sudden (acute) lameness. The degree of lameness varies from being subtle in the early stages to non-weight bearing. The affected foot may be warm or even hot to the touch, and the digital pulse felt at the level of the fetlock is usually increased.
If the horse has a shoe on the foot, the shoe should be removed. Hoof testers are frequently used to find the exact source of pain. The white line may also be lightly pared using a hoof knife to identify any tracts that could indicate the location of the abscess. Once the location of the abscess is known, the vet or farrier can open the abscess to allow the pus to escape (the pus may be grey/black), which will release the pressure and relieve the pain. Antibiotics aren’t given as they don’t reach the abscess through the bloodstream. If your horse is not up-to-date with his/her tetanus vaccination you should let your vet know, as the abscess hole provides a perfect site for tetanus to enter.
After drainage is achieved, the foot is usually disinfected with soaks in either a salt solution (Epsom Salts) or a diluted antiseptic such as iodine. After disinfection, the foot can be wrapped dry or with a poultice. There are a variety of effective solutions on the market, but the key is to keep the foot clean and protected during the healing phase. For pain an anti-inflammatory agent such as Phenylbutazone (Bute) can be used to keep your horse comfortable.