Chronic Foot Abscess in a Horse

A fifteen year old gelding presented to PHD veterinary services for the complaint of recurrent foot abscesses. Over the past 2 months, the gelding has suffered from 2 abscesses in the same foot. Physical exam revealed a draining abscess from the outside (lateral) margin of the sole and the horse was lame at the walk. A radiographic study of the foot was performed. In Figure 1, the lateral view of the foot is represented. There is no evidence of laminitis and there appears to be adequate sole depth (>1cm). However, careful examination of the palmar (bottom) portion of the coffin bone revealed an area of radiolucency in the bone (yellow circle and yellow arrows).

Figure 1

In Figure 2, the same radiolucency can be seen in the outside (lateral) portion of the coffin bone (yellow arrows and circle) AND is associated with the radiolucency (blue arrows)  immediately below it which is the current abscess that is draining from the bottom of the foot.

Figure 2

In Figure 3, the downwardly projected radiograph clearly identifies the defect within the coffin bone (yellow arrow and yellow circle).  In addition, the full extent of the abscess is noted by the blue arrows which nearly encompass the entire lateral aspect of the sole. The "black hole" noted inside the yellow circle corresponds to a region of the coffin bone which as been invaded by infection or possibly a tumor. The most likely scenario is a chronic abscess which has resulted in osteomyelitis (bone infection) of the coffin bone. Further diagnosis and treatment will involve a veterinary surgeon and exploration of the coffin bone defect. 

Figure 3

 Typically, foot abscesses do NOT result in a bone infection. However, if the initial abscess is not treated aggressively with disinfecting foot soaking and proper bandaging, it is possible to have such a complication. I typically recommend 7 days of epsom salt solution soaking along with bandaging the foot with a variety of "packing" material. In the case of large sub-solar abscesses, I strongly recommend the use of a hospital plate or specialized boot.