Sequestra of the distal phalanx in horses can occur secondary to a puncture wound that reaches the level of the distal phalanx, or they can result from a deep subsolar abscess, especially in a horse with chronic laminitis. The most common clinical sign is a hoof abscess. In any horse that has recurrent hoof abscesses in a particular region of a foot, a sequestrum is a potential differential diagnosis.
In many cases, a sequestrum can be identified on radiographs (see distal phalanx sequestrum image). In suspected sequestrum cases after puncture, waiting 2–3 weeks may be necessary to identify the lesion. Packing the bottom of the foot (sulci of the frog) eliminates the gas shadows of the frog and can make identification of the sequestrum easier.
Courtesy of Dr. Valerie J. Moorman.
Multiple radiographic projections are often necessary, including oblique dorsoproximal-palmarodistal (plantar) views. Advanced diagnostic imaging (CT or MRI) may be necessary when radiographic signs are more subtle.
Sequestra in horses are treated by surgical debridement and removal through the solar surface of the hoof. In rare cases when the sequestrum is not located at the solar margin, a surgical approach through the hoof wall may also be needed. The hoof must be bandaged or shod with a treatment plate after surgical debridement so that the solar defect can heal without being contaminated. Administration of antimicrobials, both systemically and locally, is also indicated after surgical debridement.
The prognosis is good if the infection can be controlled and the sequestrum does not involve synovial structures.
