Plasma concentrations of Cortisol in cows with hypocalcaemia in relation to their responses to treatment with calcium

Abstract

The mean plasma concentration of cortisol at the time of the first treatment for hypocalcaemia at calving was significantly higher in 17 cows which did not recover, than in 53 cows which recovered. Healthy periparturient cows had significantly lower cortisol levels than cows with hypocalcaemia. There was a negative correlation between plasma cortisol and plasma calcium at the time of the first treatment. After adjustment for differences in plasma calcium there was no significant difference between cortisol concentrations in healthy cows and paretic cows which recovered. Plasma cortisol was positively correlated with both packed cell volume (PCV) and serum creatine kinase (CK). At first treatment cows which did not recover had higher levels of PCV and serum CK than cows which recovered, and the difference between the mean plasma cortisol concentrations of these two groups was related to differences in plasma calcium, PCV and serum CK. Plasma cortisol concentrations remained high in cases of protracted paresis.