Fibrotic myopathy of the iliopsoas muscle in a dog.

Fibrotic myopathy of the iliopsoas muscle developed in a dog, following extensive migration of a grass awn within the muscle and adjacent subcutaneous tissue. The dog was initially presented for evaluation of a fluctuant swelling over the right flank region. The clinical and imaging findings were suggestive of iliopsoas fibrotic myopathy and the diagnosis was confirmed by histopathology. This is the third report of iliopsoas fibrotic myopathy in a dog, the first report to describe the postmortem pathologic changes and the first report of iliopsoas fibrotic myopathy subsequent to foreign body migration.