Efficacy and Safety of 1α-Hydroxyvitamin D3 for Prevention of Parturient Paresis

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Abstract
Four trials involved i.v. or i.m. injections of 1.alpha.-hydroxyvitamin D3 to test efficacy in preventing parturient paresis. Use of .1 mg i.v. afforded total protection compared with an incidence of 33% (2/6) in controls. I.m. injections of .1 mg in 2 ml propylene glycol and .3, .5 and 1.0 mg in 5 ml corn oil resulted in 0, 16.7, 20 and 0% incidence of parturient paresis compared with 33, 16.7, 37.5 and 37.5% incidence of parturient paresis in the controls. There was a rapid increase in serum Ca (12-24 h) in response to i.v. treatment; the response to i.m. injections was gradual but was maintained longer. To evaluate the safety of 1.alpha.-hydroxyvitamin D3, 8 cows, 2 per treatment, were given i.m. doses of .5, 1.0, 1.5 or 3.0 mg (three 1.0 mg injections) in 5 ml corn oil. No clinical or pathological evidence of hypervitaminosis D or soft tissue calcification was found. Tissue taken from the injection site 15 days after last injection contained 3-38 IU vitamin D activity/100 g wet tissue compared with control of 8-15 IU/100 g. Total vitamin D activity of milk taken the 11th milking postpartum from cows receiving .5 or 1.0 mg had a mean of 13.4 and 22.6 IU vitamin D activity/l compared to 19 IU/l for control milk. Milk from the 5th milking postpartum in the cows receiving .5 mg had a mean activity of 14.5 IU/l. Milk from animals slaughtered for retention studies had a mean activity of 22 IU/l.