Calcium salts for treating hypocalcemia: carrier effects, acid-base balance, and oral versus rectal administration.

Oral Ca salt supplements are being used to combat hypocalcemia in dairy cows. The absorption of these Ca supplements is dependent on the salt and carrier used. In the studies presented, the magnitude of the rise in plasma Ca concentration following administration of the Ca preparation was used as an index of Ca absorption by the gastrointestinal tract. Calcium chloride preparations in a water-soluble carrier (propylene glycol) were absorbed more readily than Ca propionate in propylene glycol, but Ca propionate effected a more sustained increase in plasma Ca concentration. Vegetable oil preparations of these salts were poorly absorbed. Calcium chloride preparations induced a significant decrease in blood and urine pH. Calcium propionate salts did not alter acid-base balance. Rectal administration of Ca salts could raise plasma Ca concentration rapidly, but caused serious pathological lesions, precluding their use.