Hypertrophic Osteodystrophy in Two Red Wolf (Canis rufus) Pups

Abstract

A 6-month-old red wolf (Canis rufus) pup presented for evaluation of progressive thoracic and pelvic limb lameness, joint swelling, and decreased body condition. Radiographic evaluation revealed medullary sclerosis centered at the metaphyses of multiple long bones, well-defined irregular periosteal proliferation, and ill-defined lucent zones paralleling the physes, consistent with hypertrophic osteodystrophy (HOD). Biopsies of affected bone revealed medullary fibrosis and new bone formation. The pup improved following treatment with nonsteroidal anti-inflammatories, opioids, and supportive care over the course of 4 weeks. Metaphyseal periosteal bone proliferation persisted until the animal was humanely euthanized several years later for poor quality of life associated with bilateral cranial cruciate ligament rupture. A second red wolf pup of 4.5 months of age presented for evaluation of lethargy, kyphotic posture, and swollen carpal and tarsal joints. Radiographs revealed bilateral medullary sclerosis and smooth periosteal reaction affecting multiple long bones, suggestive of HOD. Further diagnostics were not pursued in this case to confirm the diagnosis, and the clinical signs persisted for 4 weeks. In light of these two case reports, HOD should be recognized as a developmental orthopedic disease in growing red wolves.