Mandibular hypertrophic osteodystrophy fibrosa in a german shepherd puppy

Hypertrophic osteodystrophy is a developmental disease of unknown etiology and affects primarily young rapidly growing large and giant breed dogs. The present study reports a case of mandibular hypertrophic osteodystrophy fibrosa in a 6-month-old male German shepherd puppy admitted with a history of one month decreased appetite, difficulty in chewing, and open mouth with continuous drooling. Clinical examination revealed thickened mandible and filling of the intermandibular space with hard tissue. Radiography revealed bone-like material filling the intermandibular space. Biopsy from the thickened mandibular mass demonstrated marked osteoclastic activity and resorption of bone trabeculae that were replaced by fibrous connective tissue. The marrow cavity was filled with massive fibrous tissue mixed with hemorrhage and osteoclasts. Hypertrophic osteodystrophy fibrosa should be taken into consideration in dogs with mandibular masses. Radiography and histologic evaluation are suitable tools to differentiate hypertrophic osteodystrophy. fibrosa from mandibular neoplasms and cranio-mandibular osteopathy.