Horses: Subsolar Abcess

Dr. Harper’s Case report:

Imagine you come home from a hard day of work. You go out to the barn to feed, water, groom, etc. As you call the horses in from pasture, you notice one taking an unusually long time to come up. You go to investigate. Just over the hill you find him. . . but something is not right. Is he not using his front left leg? He’s not!! Not at all!! He can barely walk!! What could have happened? Is it broken? Am I going to have to have him put to sleep? What do I do?

Although a broken leg is certainly possible, it is not the most common cause of the above scenario. More than likely your horse has a Subsolar abscess.

Subsolar abscess is the number one cause of acute lameness in the horse. Basically, it is an infected area that has developed beneath the sole of the foot or wall of the hoof. It generally begins with a defect in the sole itself. This could come about as a result of a hole, crack, puncture wound, etc. Often times the offending agent is never identified. This defect in the sole allows for contamination of the sensitive underlying tissues with bacteria.  As the bacteria replicate, an abscess forms and is extremely painful. Most horses present with a sudden, severe lameness. They are very reluctant to bear weight and tend to walk with a ‘toe-pointing’ manner. In many cases it is considered a true emergency.

Your veterinarian can diagnose a subsolar abscess by using a variety of techniques. Of course, history and clinical signs are very important. The most useful diagnostic test is probably the use of a device called ‘hoof testers’. This instrument allows the veterinarian to apply precise pressure over entire sole of the foot which allows him/her to pinpoint the exact location of the abscess. Occasionally additional diagnostics may need to be used such as blocking out the foot, radiographs, etc. Usually, horseshoes will have to be removed.

Once the source of the pain is identified, your veterinarian will pare out the abscess site. This involves using a variety of instruments to basically dig through the insensitive tissue of the sole to allow drainage of the infection. Once the abscess is opened, the pain will begin to be relieved. Often times, it may take several days to get the abscess completely open and draining adequately. A series of soaks in Epsom salt baths followed by foot wraps with a drawing agent may be necessary to get the abscess draining. Additionally, a tetanus shot is important to get anytime a horse has any type penetrating injury.

Treatment of the abscess involves five basic components: (1) Ventral drainage, (2) Antiseptic soaks, (3) Local antiseptic irrigation, (4) A disinfecting dressing and (5) Bandaging. These steps are repeated on a daily basis until the lameness has subsided, the abscess stops draining and sole begins to repair itself. This may take two to four weeks depending on the extent of the abscess. As long as vital, deep structures (i.e. the navicular bursa, coffin joint, etc.) are not involved, the prognosis is good. It should not affect the future soundness or performance of your horse. Delaying treatment will allow the infection to reach these important underlying tissues and could end the career, possibly the life, of your horse.

So as you go out to feed your horses tonight, pay attention to their gait. If one appears acutely, nearly non-weight bearing lame, the worst-case scenario of a broken leg is possible. However, more than likely he has a subsolar abscess that a trip to Cooper Veterinary Hospital can diagnose, treat and have you back riding again in no time

                                                            (Photos of Peppy being treated in the hospital)