Foot Abscesses - Diagnosis and Treatment
With wet weather, horses are standing in mud. This softens the sole of the hoof causing tiny cracks, especially at the white line (the junction of the sole and the hoof wall). Dirt then works its way up under the sole where bacteria flourish. Cracks can also form from trauma to the sole resulting in severe bruising. A penetrating object such as nail can open a pathway to the outside and provide an inoculum of bacteria. All these can start an infection.
Over a period of days the infection spreads causing an abscess to form. Typically what happens is that your horse will seem a bit lame one day. The next day he will be so lame he won’t put any weight on the leg at all. Many owners will call the vet thinking their horse has a broken leg. This severe pain results because the abscess is expanding within the hard casing of the hoof. This applies tremendous pressure within the hoof resulting in throbbing pain.
Diagnosis is achieved by applying point pressure over the sole of the hoof with hoof testers. These look like large pliers. When the testers apply pressure over the abscess the horse will react by pulling away, often with great enthusiasm.
Treatment
The primary treatment is to try to draw the abscess to a head using poulticing techniques and if possible lance the abscess. At the initial examination I will attempt to find and lance the abscess. If the abscess can be lanced the horse will then be treated medically for 5 to 10 days. f the abscess cannot be found, the treatment is medical. First the horse’s foot will be bandaged with a tar-like substance called Icthamol (it is extremely icky). The sole is covered with cotton and then over wrapped with a bandage like proflex or duct tape. Since horses are so heavy and can easily walk through such a bandage a plastic boot is then used to keep the hoof clean.
The owner is then instructed to unbandage the foot each day. Soak the foot in warm water and Epsom salts for 20 min. Then rebandage the hoof as described above. I recheck the horse in 4 to 7 days. At that time I will again try to lance the abscess.
Most abscesses will either come to a head and are lanced at the recheck or simply disappear without ever popping as a result of the medical treatment. The average recovery time is about 10 days. In rare cases an abscess will need to be treated for over a month before resolving.
You may be wondering why, if a foot abscess is a bacterial infection, it’s not treated with antibiotics. The reason is that circulation to the foot and antibiotic penetration of an abscess is poor. As a result, antibiotics cannot reach high enough levels in the abscess to eliminate the infection. If antibiotics are used they will only suppress the abscess, which will reappear once they are withdrawn. There are always some exceptions to this premise but they must be considered on a case by case basis.