Use of pamidronate to reverse vitamin D-3-induced toxicosis in dogs

Objectives-To determine whether pamidronate disodium can reduce vitamin D-3 -induced hypercalcemia in dogs and whether combination treatment with calci tonin is more effective than treatment with pamidronate alone. Animals-20 clinically normal male Beagles. Procedure-All dogs were given 8 mg of Cholecalciferol (CCF)/kg of body weig ht once orally, then were assigned randomly to groups Of 5 dogs each. Dogs were given 0.9% NaCl solution IV (group 1),calcitonin SC and 0.9% NaCl solu tion IV (group 2), pamidronate and 0.9% NaCl solution IV (group 3), or a co mbination of all 3 agents (group 4). Dogs were observed for 28 days, and se rial blood and urine samples were collected for determination of serum bioc hemical; electrolyte, and 25(OH)D-3 values, CBC, and urine mineral excretio n. Samples of kidney, stomach, lung, aorta; liver, duodenum, and brain were evaluated by light microscopy and quantitative mineral analysis. Results-Two dogs in group 1 were euthanatized 4 days after CCF administrati on because cif severe clinical signs of disease; Dogs in group 3 lost less weight and had significantly lower serum phosphorus, total and ionized calc ium, and urinary zinc concentrations, compared with dogs in group 1. On day , serum urea nitrogen concentration was significantly lower in dogs of grou ps 3 and 4 compared with dogs in group 1. Mild to moderate mineralization o f kidneys and stomach were observed in the 2 group-1 dogs euthanatized on d ay 4. Conclusions-Pamidronate administration effectively prevents CCF-induced hyp ercalcemia and mineralization of soft tissues. Clinical Relevance-Pamidronate is a potentially useful antidote;against CCF toxicosis in dogs.