Therapy for hypercalcemia of malignancy is two-fold: treatment of the hypercalcemia if necessary and, more importantly, of the underlying malignancy. Animals with clinical signs of hypercalcemia beyond polyuria (e.g., weak, vomiting, bradycardic), typically those with total calcium ≥18 mg/dL, should be hospitalized and treated with aggressive fluid therapy using a calcium-replete solution (e.g., 0.9% NaCl at >66 ml/kg/day with urine output goal of 2 ml/kg/hr). Furosemide (2–4 mg/kg PO, SC, or IV bid) may be administered to promote calciuresis, provided the patient is well hydrated. Aside from serious clinical signs, other indications for treatment include a calcium phosphorus product (total calcium × phosphorus) ≥60. Other pharmacologic options for decreasing calcium include prednisone (1–2 mg/kg PO, SC, or IV bid), calcitonin (4-6 IU/kg SC bid to tid) or bisphosphonates. ²² The use of prednisone is ill-advised unless the patient has been screened for lymphoma, since steroid use may induce remission of this disease and can make subsequent diagnosis impossible. Calcitonin use may fall out of favor now that bisphosphonates are available and have been used in veterinary patients. Patients with unresolved hypercalcemia after saline-induced diuresis and furosemide should be treated with pamidronate at 1 mg/kg given over 2 hours in 250 ml 0.9% saline. ^22,23 Effective treatment of the underlying malignancy is the approach most likely to resolve the hypercalcemia.