A foot/sole abscess, often referred to as a subsolar abscess, is an accumulation of pus beneath the sole of the foot. It is characterized by a sudden onset of non-weight bearing lameness, similar to the severity of a horse with a fracture.
Abscesses are an inflammatory response to an organism (usually bacterial or fungal) or other foreign matter such as gravel, dirt, sand or manure that has got into the inner walls of the hoof. The organism gains access through a misplaced nail or puncture wound on the sole surface of the foot or multiple nail holes.
The horse will continue to be in pain until the accumulation of pus is able to drain from the foot. The initial wound or point of entry of the organism or foreign body into the hoof is not always visible or may have already started to close. If this is the case, then your veterinarian may need to remove a small portion of the frog or sole of the foot using a sharp hoof knife in order to better evaluate the situation. The date of the horse's last tetanus shot should be confirmed to ensure horse is up to date. Otherwise, they will require a tetanus shot.
The goal of treatment is to drain the accumulated pus from the abscess. It is important that during this time, the horse is kept in a clean stall with soft bedding and that the horse is kept comfortable. Usually, with hoof abscesses, once the abscess has drained, horses will show almost immediate relief and are no longer lame on the affected foot.
Once all pain has ceased and abscess drained, the horse can be reshod or a boot applied to prevent further contamination until the wound has completely healed.