Immune-mediated pyogranulomatous panniculitis with hypercalcemia in a dog.

An 11-year-old neutered male large crossbreed dog was presented for investigation because of a 10-day history of progressive lethargy, hyporexia, and pyrexia. Physical and dermatological examinations were unremarkable. Blood biochemical analysis identified a marked total and ionized hypercalcemia and increased C-reactive protein concentration. Bicavitary computed tomography screening for causes of the dog's clinical and biochemical abnormalities identified a diffuse panniculitis. Histopathological examination of full-thickness skin biopsies was consistent with pyogranulomatous inflammation. Extensive histochemical staining revealed no infectious etiology. Complete clinical and biochemical remissions were observed after starting immunosuppressive, followed by tapering, doses of prednisolone, supporting an immune-mediated etiology. Key clinical message: Sterile, immune-mediated pyogranulomatous inflammation should remain a differential diagnosis for hypercalcemia in dogs. Significant dermatological disease may occur without visible abnormalities.