Practical use of a combination of a dopamine agonist and a synthetic prostaglandin analogue to terminate unwanted pregnancy in dogs.

The combination of a dopamine agonist, cabergoline, and a synthetic analogue of prostaglandin F2 alpha, cloprostenol, was used to induce termination of pregnancy from day 25 after the estimated luteinising hormone surge (day 27 +/- 4 after the first mating) in five mature beagle bitches. Cabergoline was administered orally at 5 micrograms/kg daily and cloprostenol was injected subcutaneously at 1 microgram/kg every other day. Treatment efficacy, in terms of pregnancy termination, was 100 per cent. Termination always took place by resorption of the fetuses. No side effects were observed. A mean of three injections of cloprostenol and nine days of cabergoline treatment was necessary to eliminate all signs of gestation. Termination was in each case accompanied by a decline in plasma progesterone (to less than 1 ng/ml) within 72 hours of initiation of treatment. In a control group of five, untreated bitches, plasma progesterone remained elevated throughout a corresponding period (from day 25 to day 50 after the estimated luteinising hormone surge). In the treated group, interoestrous intervals (98 +/- 41 days) were reduced, compared with previous cycles (194 +/- 9 days) or with those of the control animals (205 +/- 37 days). It is concluded that the combination treatment with the anti-prolactinic agent, cabergoline (5 micrograms/kg/day), and the synthetic prostaglandin F2 alpha, cloprostenol (1 microgram/kg/two days), is an easy, practical, reliable and safe method to terminate pregnancy near and before mid-gestation in dogs.