Potential use of 1,25-dihydroxycholecalciferol for prevention of parturient paresis.

Twelve cows, at least third parity, were assigned randomly to either a control or treatment group. Treated cows received .4 mg of the vitamin D metabolite, 1,25-dihydroxycholecalciferol intramusculary in 5 ml corn oil. Intramuscular injections were started 5 days before predicted calving with reinjections every 5 days until calving. Incidence of parturient paresis was 0 and 33% (2 of 6) in the treated and control groups. Response to treatment was rapid with elevated calcium in serum approximately 12 h postinjection. Treatment maintained or elevated calcium and phosphorus concentrations in serum during the critical period, 24 h pre- to 48 h postpartum, when milk fever is most likely to occur. There was, however, no significant difference between treatments at 72 h postpartum. Based on these observations 1,25-dihydroxycholecalciferol holds promise as a preventative of parturient paresis; however, further studies are needed on application and safety.