Lameness Associated with Coxofemoral Soft Tissue Masses in Six Dogs

Six cases of mechanical lameness involving the coxofemoral joint are presented. All dogs had a history of chronic rear leg pain and lameness, and decreased range of motion of the hip. On physical examination, ventral subluxation of the coxofemoral joint during extension was present in three dogs. A radiographic diagnosis of subluxation was made in five dogs. In each dog, surgical exploration of the area caudal to the coxofemoral joint revealed a fibrous mass between the lesser or third trochanters and the ischium, diagnosed as a nonneoplastic fibrous reaction by microscopic examination. The clinical, radiographic, and histopathologic signs were similar to previously described cases of myositis ossificans. Five dogs returned to normal function after excision of the soft tissue mass, and one dog was normal when lost to follow-up 4 weeks postoperatively.