A five-month-old male Labrador retriever presented with massive bilateral jaw and facial swelling. Ulcers were found on the buccal mucosa and palate, and the jaws were flexible on firm palpation. The dog could eat only soft food and was underweight. Renal hyperparathyroidism was diagnosed based on serum chemistry screen, parathormone concentration, radiological findings and histopathology. The dog was euthanatized because of an extremely poor prognosis.