Emphysematous Osteomyelitis: A Rare Manifestation of Osteomyelitis in Dogs. Multimodality Diagnostic Imaging and Evaluation of Clinical Progression.

While osteomyelitis is not uncommon in veterinary patients, emphysematous osteomyelitis, characterized by the presence of intramedullary gas, is scarcely reported in both veterinary and human literature. This report documents two cases in young, previously healthy dogs that were presented with clinical signs related to infection/inflammation. Multiple imaging modalities were utilized in the workup of one case, while computed tomography (CT) was used as the sole modality in the second. In both cases, peri-femoral abscessation with intramedullary gas was identified, and positive bacterial culture was obtained. One case responded well to treatment and demonstrated expected osseous remodeling consistent with chronic osteomyelitis. The patient in the second case was euthanized secondary to a marked clinical decline. In humans, this condition is often associated with comorbidities, including diabetes mellitus and carries a guarded prognosis, with a 24-32% mortality rate. The presence of multiple, variably sized though small, irregularly marginated foci of gas, without a sclerotic rim within the medullary cavity, without a history of penetrating trauma, necrotic tumor, or recent surgery, should be considered pathognomonic for emphysematous osteomyelitis.