Hypocalcaemia and Q-oTc interval in cows with parturient paresis.

The degree of hypocalcaemia was determined from serum total, and serum ionized calcium concentrations in 27 cows with parturient paresis. Electrocardiographic recordings were made just before the start of the intravenous calcium treatment. The T-oTc interval was determined, but could only be adequately measured in 16 cases because of inherent difficulties in recording from paretic animals. No significant correlation was found between the degree of hypocalcaemia and Q-oTc interval, whether the hypocalcemia was determined from serum total or serum ionized calcium concentrations. This study indicated that measurement of the Q-oTc interval was of very little value as a clinical test for detection of hypocalcaemia and indication of the degree of hypocalcaemia in parturient paresis.