ABORTION INDUCTION IN THE CAT USING PROSTAGLANDIN F(2)ALPHA AND A NEWANTI-PROLACTINIC AGENT, CABERGOLINE

This study in cats compared the effects of a natural prostaglandin F2a lpha (PGF2alpha) and cabergoline, administered on and after day 30 aft er mating, with regard to the plasma progesterone concentration, the i nduction of abortion and the side effects of each regimen. PGF2alpha, through a direct luteolytic action, induced abortion by an abrupt and rapid (24 h) decline in the plasma progesterone concentration. Using d oses (2 mg per cat) comparable to the ones selected in a previous stud y, 100% of abortions (4/4) in cats treated from day 33 of gestation we re obtained. Cabergoline (1.65 mug kg-1 day-1, administered subcutaneo usly for 5 days), through its antiprolactinic action induced abortion in 80% (4/5) of the cats treated on day 30 of gestation. The abortion was initiated by means of a reduction in plasma progesterone concentra tion to < 1 ng ml This reduction was not as rapid (3-4 days), however, as that obtained with PGF2alpha (24 h). Prostaglandins always induced significant side effects such as nausea, prostration, vomiting and di arrhoea, within 10 min following injection, whereas cabergoline never induced side effects or behavioural disturbances. In addition, cabergo line usually induced abortion through fetal resorption (75% of cases), without any clinical sign other than some vaginal discharge.