Effect of stress due to laparoscopy on plasma cortisol levels, the preovulatory surge of LH, and ovulation in the ewe.

The ovulation which is induced in seasonally anovular ewes by the introduction of rams was used as a model to examine the effects of the stress of repeated laparoscopy on the preovulatory surge of LH and ovulation. The number of ewes which experienced LH surges and ovulation was reduced (10/23 vs 1/20) when laparoscopy was repeated every four hours. Plasma cortisol levels were used as an indicator of stress, and were found to increase after laparoscopy: a single laparoscopy produced a transient rise, while repeated laparoscopy induced and maintained levels between 70 and 100 ng/ml.