Computed tomographic features of skull osteomyelitis in four young dogs

Computed tomography (CT) features of four immature to young adult dogs with osteomyelitis of the skull are described. Trauma or bite wounds were the cause of infection and Staphylococcus aureus was the most common pathogen. CT features were a combination of soft tissue thickening, bone lysis, and bone proliferation. Bone lysis was extensive in some dogs with a moth-eaten appearance and involved the calvarium, base of the skull, the frontal sinuses, and the temporomandibular joint. In other dogs it was more focal with thinning of the bone rather than complete lysis. Bone proliferation also varied in appearance from irregular palisading or spiculated to expansion and septation of the frontal bone. Sequestrum formation was seen in one dog. Widespread infection in one dog involved the tympanic bullae and the temporomandibular joint. Lysis of the calvarium resulted in bacterial meningitis in two dogs. One dog was euthanized and three were treated with surgical curettage of the affected bone and antibiotic therapy which resulted in resolution of the clinical signs in one dog whereas two dogs had recurrent disease. CT was very helpful for characterizing extent and localization of the infection. Despite the aggressive CT features, osteomyelitis should be considered especially in young animals with a history of trauma or bite wounds. The pathophysiology of skull bone infections is discussed.