Osteomyelitis Group 9 SA, skeletally mature, hematogenous 1. Signs, symptoms, history, PE, specialty exam findings In older, skeletally mature animals, the tightly bound periosteum causes the material (bacteria) to form holes through the bone that become connected by fistulous tracts to the skin surface. The dead bone provides a protective haven for the bacteria from the bodyÕs defense system which results in a cyclic buildup and release of pus through the fistulae. Presenting history could include worsening lameness (probably unilateral), pain, and evidence of draining tracts. Inappetance, periodic febrile episodes, and fluctuant swellings may also be observed. n addition, iatrogenic contamination could be the origin of the condition, perhaps via a previous surgical procedure or fracture, perhaps combined with a fungal infection. Specialty exam findings might include leukocytosis, hyperproteinemia, and thrombocytosis. Radiographs could show a sequestrum with an involucrum. 2. Management plan and prognosis Both local and systemic treatment is necessary. Culture and sensitivity for aerobic and anaerobic bacteria should be performed before starting systemic antimicrobials. In the meantime, a temporary broad-spectrum antibiotic should be administered (such as clindamyin, cefazolin, etc.). This antibiotic regimen is the same as for Case 3. Bone fragments must be approached surgically if unstable or dead; rigid stabilization is essential. All avascular fragments of bone are discarded (bone is rongeured until bleeding). The infection may require lavage in preference to a bone graft in the early stages. Prognosis is guarded until dead bone is removed, after which the prognosis is fair. 3. How, why is situation different from or similar to Case 3? Bone sequestration due to lower limb wounds is much more common in large animals than in small because there is little soft tissue coverage, the bones are located close to the ground, and are in an area that is easy to injure the periosteum, and therefore disrupt a portion of the blood supply to the bone. In large animal neonates, it is more common to have acute osteomyelitis of the growth plate.