A 3 month old labrador retriever puppy presented with rather acute lameness and soft tissue swelling especially around the distal antebrachiocarpal joints. The patient appeared to be systemically ill and was febrile, anorectic, and reluctant to walk. Radiographs were made of both antebrachiocarpal and tibiotarsal joints. Studies are shown of one region. Describe the radiographic changes. What is the diagnosis and prognosis? The radiographic changes are centered in the slightly enlarged metaphyses (arrows) and are primarily destructive in nature. Note the symmetry of the lesions. Examination of the entire radiographic study showed the metaphyses of all long bones to be similarly affected with the more prominent lesions distal in the bones and distal in the limbs. The radiographic diagnosis Hypertrophic osteodystrophy (HOD) is a polyostotic disease with unknown etiology that produces destructive lesions that center on the metaphyses of the long bones. Usually puppies of large and giant breeds are affected between 2 and 6 months of age. Presentation is as described for this patient.A differential diagnosis should include bacterial hematogenous osteomyelitis. The perfect symmetry and involvement of only long bone metaphyses tends to rule out this possibility.Most dogs recover spontaneously and all necrotic tissue and the cuff of dystrophic calcification are removed by osteoclasts. The repair by osteogenic granulation tissue reconnects the new primary spongiosa to remaining unaffected secondary spongiosa. Thus, the lesions are not recognized in the mature skeleton.A few dogs have been reported to have concomitent respiratory disease and more severe systemic signs with death resulting from the associated pneumonia. Joe P. MorganProfessor EmeritusDepartment of Surgical and Radiological SciencesSchool of Veterinary MedicineUniversity of CaliforniaDavis, CA 95616jpmorgan@ucdavis.edu
