Multifocal costal osseous pneumatosis and osteomyelitis secondary to Clostridium botulinum in a dog.

A 3-year-old castrated male German shepherd dog was presented with a 48-hour history of lethargy and anorexia. On presentation, the dog was laterally recumbent, hyperthermic, tachycardic, severely dehydrated, and exhibiting abdominal pain. Abdominal radiographs raised suspicion for splenic torsion. An exploratory laparotomy revealed a suspected splenic vein thrombosis, prompting a splenectomy and an incisional gastropexy. Computed tomography revealed multifocal osseous pneumatosis, rib abscesses, costochondral luxation, renal infarcts, suspected intramuscular thrombosis, aspiration pneumonia, and lymphadenopathy. Despite negative blood culture and peri-costal abscess cultures, Clostridium botulinum was isolated from bone marrow obtained via costochondral rib aspiration. During hospitalization, persistent non-regenerative anemia and thrombocytopenia were observed; the dog was also nonambulatory tetraparetic, worse on the right, indicating a predominantly right-sided myelopathy. After some improvement, the dog was discharged from the hospital; however, his condition progressively worsened despite treatment, leading to humane euthanasia 1 mo later. Necropsy revealed disseminated round cell tumor consistent with lymphoma. Key clinical message: Visceral organ gas accumulation or intraosseous gas in the absence of previous trauma or surgery should prompt suspicion for an anaerobic infection. To the authors' knowledge, this is the first reported case of rib pneumatosis secondary to disseminated C. botulinum in a dog.