Four trials involved intravenous or
intramuscular injections of 1alpha-hydroxyvitavin D3 to test efficacy in preventing
parturient paresis. Use of .1 mg intravenously afforded total protection compared with an incidence of 33% (2/6) in controls.
Intramuscular injections of .1 mg in 2 ml
propylene glycol and .3, .5, and 1.0 mg in 5 ml
corn oil resulted in 0, 15.7, 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
calcium (12 to 24 h) in response to intravenous treatment, whereas the response to
intramuscular injections was gradual but was maintained longer. To evaluate the safety of 1alpha-hydroxyvitamin D3, eight cows, two per treatment, were given intramuscular 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 C or soft tissue calcification was found. Tissue taken from the injection site 15 days after last injection contained 3 to 38 IU
vitamin D activity per 100 g wet tissue compared with control of 8 to 15 IU per 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 per liter compared to 19 IU per liter for control milk. Milk from the 5th milking postpartum in the cows receiving .5 mg had a mean activity of 14.5 IU per liter. Milk from animals slaughtered for retention studies had a mean activity of 22 IU per liter.