Brachialis muscle contracture as a cause of lameness in cats: A study of four cases.

Three cats (four cases) were presented to two hospitals in New Zealand with limited extension of the elbow, and a nonpainful, firm mass on the craniolateral aspect of the distal humerus. Findings in all cases were consistent with brachialis muscle contracture. In one case, there was also contracture of the biceps brachii muscle. Ultrasound imaging (used in three cases) showed a heterogeneous, increased echogenicity of the muscle. The histopathology results were obtained in three cases; two were diagnosed as fibrosis of the muscle, one as a soft tissue sarcoma. All cases were treated surgically by myectomy, which resulted in restoration of full elbow motion and permanent resolution of lameness in all the cases due to fibrotic muscle contracture. To date, there is only one reported case of brachialis muscle contracture and no reports of biceps brachii muscle contracture in the published literature. In one case, the aetiology was a soft tissue sarcoma, which, to the best of the authors' knowledge, has not been previously reported. A neoplastic aetiology can significantly change the prognosis for the patient and highlights the importance of obtaining histopathology in muscle contracture cases.