Abstract
1. Background
Canine inflammatory myopathy (IM) is a disease characterized by nonsuppurative cellular infiltration of the skeletal muscle. Dermatomyositis is primarily observed in Collies, Sheepdogs, and their crossbreeds. However, it also appears sporadically in other species. "Dermatomyositis-like disease" is the term used in such cases. Dermatomyositis-like disease has been occasionally described in other breeds, but it has never been reported in Poodles. Additionally, cases in adult dogs have not been reported. This report outlines the successful management of a case involving an adult small breed dog with dermatomyositis-like disease through the use of immunosuppressive drugs and supportive medications.
2. Case presentation
A 10-year-old spayed female Toy Poodle dog presented with nasal edema, erythema, pain, pruritus, and discharge. The size oflesion had gradually increased, measuring 29×22.8×17.8 mm at the first visit. No infection was detected on microscopic cytologic evaluation of the nasal discharge. On radiography and computed tomography (CT), the nasal septum structure was normal, and bony invasion was not identified. On rhinoscopy, the soft tissues were thickened and erythematous. Decreased lumen diameter and severe congestion were found in the right nasal cavity. On histological examination, there was multifocal-to-coalescing moderate-to-severe inflammation and fibrosis in the deep dermis and skeletal muscle layer. The inflammatory cells were primarily lymphocytes and plasma cells.
3. Conclusions
Based on the patient history and test results, the patient was diagnosed with canine dermatomyositis. Treatment included immunosuppressive agents (prednisolone, cyclosporine) and antibiotics (amoxicillin/clavulanate). This treatment reduced the nasal edema, nasal erythema, and size of lesion. The patient’s clinical signs improved after treatment, and the dog demonstrated clinical benefits at a follow-up visit at 17 weeks. Although canine dermatomyositis usually develops before six months of age, this report demonstrates that this disease can also occur in adult dogs.