Osteomyelitis Associated With Disseminated Blastomycosis in Nine Dogs

Blastomycosis, a common disease entity of dogs in the southeastern United States, may be encountered elsewhere. Blastomyces dermatitidis, the cause of this disease, is a soil‐borne fungal organism. B. dermatitidis is introduced into the host by inhalation of infective spores. This results in a primary lung infection. Dissemination of the organism occurs by lymphohematogenous means and may involve any body tissue. Other tissues frequently involved are the skin, male genitals, lymph nodes, eyes, and bone. Osteomyelitis was diagnosed in nine dogs with disseminated blastomycosis. Six of nine dogs had solitary bone lesions. All nine dogs had a clinical lameness. Only two dogs had clinical signs of respiratory disease. A total of 25 bone lesions were observed in these dogs, with 19 lesions located in the tubular bones of the extremities. Typically, osteolytic lesions appeared at the ends of long bones; only two lesions were observed proximal to the stifle. No extremity lesions were seen proximal to the elbow. Approximately half of the bone lesions had an associated periosteal response or soft tissue enlargement, while no sinus or fistulous tracts were observed. Blastomycosis was confirme