Alendronate treatment in cats with persistent ionized hypercalcemia: A retrospective cohort study of 20 cases

BACKGROUND: Limited information is available concerning treatment of ionized hypercalcemia in cats. HYPOTHESIS/OBJECTIVES: Describe clinical findings in a cohort of cats with persistent ionized hypercalcemia and evaluate long‐term tolerance and efficacy of alendronate in these patients. ANIMALS: Twenty cats with persistent ionized hypercalcemia of undetermined origin, presented for routine or referral consultation at the teaching hospital of Maisons‐Alfort (France). METHODS: Medical records were retrospectively reviewed. Cats were divided into Group 1 (cats that received alendronate as well as other treatments, n = 11) and Group 2 (cats that did not receive alendronate, n = 9). Survival analysis (Kaplan‐Meier method, log‐rank test, and Cox proportional hazard models) was conducted to compare time to selected outcomes. RESULTS: Azotemia was present in 15 cats (75%). Alendronate treatment was administered and well tolerated during the entire follow‐up period (median, 9.5 months; interquartile range [IQR], 6.3; 27) in all cats from Group 1, except in 1 cat that developed severe hypophosphatemia, prompting treatment discontinuation. Univariate analysis determined that alendronate treatment was significantly associated with shorter time to reach a 15% decrease in ionized calcium concentration (iCa) from baseline during follow‐up (119 days vs median not reached, P = .02). This association was no longer significant after adjustment for age and initial iCa. CONCLUSIONS AND CLINICAL IMPORTANCE: Alendronate overall was well tolerated with chronic use in this cohort, and can be considered a treatment option for persistent ionized hypercalcemia in cats.