Clinical presentation and outcome of Mycobacterium abscessus infection in six dogs - a retrospective study

Mycobacterium abscessus is a rapidly growing non-tuberculous mycobacterium known for intrinsic antimicrobial resistance. While well characterised in humans, reports in dogs remain limited. To describe the clinical presentation, diagnostic findings, treatment strategies and outcomes of Mycobacterium abscessus infections in six dogs.

Canine medical records between 2017 and 2025 were retrospectively reviewed. Dogs were included based on confirmed Mycobacterium abscessus infection by mycobacterial culture and/or polymerase chain reaction. Data collected included signalment, clinical signs, diagnostics, treatment protocols, outcomes and follow-up.

Six dogs of various breeds and ages were included in the study. Two dogs presented with chronic respiratory signs (2/6) (coughing and hacking), whereas the other four had cutaneous/subcutaneous nodules with draining tracts, frequently located on the right side of the trunk. All cases occurred during the winter months. Diagnosis was confirmed by culture and polymerase chain reaction in all cases; one isolate was additionally identified via MALDI-TOF. Cutaneous histopathology (performed in two dogs) showed pyogranulomatous dermatitis and panniculitis. Clarithromycin was the primary treatment in all dogs. Polytherapy with the use of additional antimicrobials varied. Clinical outcomes/follow-up were available for five dogs, with one dog fully recovered, one relapsed after discontinuation of therapy and two were euthanased. Two dogs had a concurrent staphylococcal infection.

Mycobacterium abscessus infections in dogs can mimic other chronic infections and present significant diagnostic and therapeutic challenges. Disease patterns (respiratory or cutaneous) closely resemble human cases. Culture and polymerase chain reaction are essential for diagnosis, and clarithromycin remains a key therapeutic option despite variable susceptibility.