Electrolyte disturbances and cardiac arrhythmias in a dog following pamidronate, calcitonin, and furosemide administration for hypercalcemia of malignancy.

A 13-year-old dog was diagnosed with hypercalcemia of malignancy associated with adenocarcinoma of the anal sacs. Hypercalcemia was treated with intravenous (IV) 0.9% sodium chloride (NaCl), furosemide, calcitonin, and pamidronate. Hypomagnesemia was documented by 72 hours following a single, IV dose of pamidronate. The dog subsequently underwent surgery to remove the primary tumors, and multiple cardiac arrhythmias occurred during anesthesia. This case documents electrolyte abnormalities in a dog following treatment with pamidronate in conjunction with other therapies used to manage hypercalcemia. The authors postulate that hypomagnesemia may have contributed to the arrhythmias that occurred during anesthesia. Electrolyte abnormalities should be anticipated and corrected following pamidronate therapy in canine patients.