Osteomyelitis of the calcaneus in horses: 28 cases (1972-1987).

Medical records of 28 horses with osteomyelitis of the calcaneus were reviewed to evaluate signalment, history, diagnostic and treatment methods, outcome, and long-term follow-up information. Trauma was the most commonly reported cause (24). Physical examination revealed lameness in 27 horses, and 22 (79%) had a wound or draining tract over the plantar aspect of the calcaneus. Radiography of all horses was done prior to the initiation of treatment, and follow-up radiography was done on 20 horses. The most common radiographic findings were soft tissue swelling (25), bony lysis of the calcaneus (17), bone fragments or sequestra from the tuber calcis (13), and periosteal new bone production or bony lysis of the sustentaculum tali (5). Association could not be found between initial radiographic findings and eventual outcome of the case. Positive bacterial cultures were obtained from 13 horses. A wide variety of gram-positive, gram-negative, and anaerobic organisms were isolated. Fourteen of the 15 isolates, for which susceptibilities were reported, were susceptible to penicillin, gentamicin, or trimethoprim sulfamethoxazole. Twenty-six of the 28 horses diagnosed as having osteomyelitis of the calcaneus were treated; 16 horses were treated with surgical debridement in addition to antimicrobial treatment, and 10 horses were treated with antimicrobial agents, anti-inflammatory drugs, or supportive wound care. There was no significant difference in survival rate of horses treated surgically and those treated conservatively. Six horses that were treated were later euthanatized for problems associated with chronic osteomyelitis, and 2 horses died or were euthanatized for unrelated problems. Eighteen horses (64%) were alive at last follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)