Successful diagnosis and treatment of canine polymyositis: utilizing MRI and immunohistochemistry for accurate detection

The dog was diagnosed with immune-mediated polymyositis and treatment was initiated with prednisolone at 1 mg/kg twice daily and azathioprine at 2 mg/kg once daily. Following the administration of these immunosuppressive agents, CK levels returned to normal, and the dog's exercise intolerance and lethargy resolved. The thickness of the hind legs also increased progressively. The dog has maintained an improved condition under continued immunosuppressive therapy for four months. This case highlights the critical role of MRI and immunohistochemistry in diagnosing immune-mediated polymyositis, demonstrating their alternative capability in cases where conventional electromyography (EMG) is not feasible in this context.