A 6-month-old, female border collie was referred for evaluation of hypocalcemia, hyperphosphatemia, fever, and painful ventral abdominal skin. She had recently been treated intravenously and subcutaneously (SC) with a diluted 10% calcium gluconate solution. The medical evaluation supported the diagnosis of primary hypoparathyroidism, but the subsequent hospital course was complicated by severe calcinosis cutis, which caused extensive skin necrosis and marked debilitation. This patient illustrates that administration of a calcium gluconate solution SC can be associated with extensive morbidity when administered to hyperphosphatemic patients.