Dog with multiple facial lumps caused by rare mycobacterial infection

Abstract

This case report describes a mycobacterial infection in an adult Whippet cross dog. The dog was diagnosed with Mycolicibacterium sediminis infection, a species of mycobacteria that is yet to be reported as a causative agent of infection in humans or domestic animals. The dog was presented for specialist opinion of a 6-month history of severe facial lymphadenopathy that was nonresponsive to antibiotic and immunosuppressive therapy. A necrotic lesion developed on her right antebrachium approximately 10-14 days before presentation. The dog was anaesthetised for computed tomography and nodule and skin biopsies including fresh tissue for mycobacterial polymerase chain reaction (PCR). The nodules contained pyogranulomatous inflammation and perivascular necrosis that are typically found in mycobacterial infections. The mycobacterial PCR isolated Mycolicibacterium sediminis. The dog was prescribed triple antibiotic therapy and tapered off corticosteroids, with noticeable improvement within 4 weeks and resolution of granulomas within 3 months of therapy. Presence of chronic dermal pyogranulomatous inflammation should raise suspicions for mycobacterial disease, and fresh tissue should be submitted for PCR to aid in diagnosis.