Use of 1,25-dihydroxycholecalciferol in the prevention of parturient hypocalcemia in dairy cows

Abstract

The administration of 1,25-dihydroxycholecalciferol (DHC) either i/m or i/v, to adult, non-pregnant cows resulted in a rapid and persistent dose-dependent increase in serum calcium and phosphorus, and a decrease in serum magnesium. Similar doses of 1 alpha -hydroxycholecalciferol in the same animals were much less effective in increasing the serum calcium and phosphorus levels. The administration of 600 mu g DHC 24 or more hours before expected parturition prevented the rapid decline of serum calcium and phosphorus anticipated in pregnant cows with a previous history of parturient paresis. The treatment was not effective when given 8-18 hours before parturition. In one animal given one dose of 600 mu g DHC and six doses of 270 mu g over a 22 day period before parturition, no evidence of mineralization in the kidney, heart, pulmonary artery, aorta or other soft tissues, was seen at PM, as reported after long-term administration of parent vitamin D.