Reproduction in a feral cat population and its control with a prolactin inhibitor, cabergoline

A feral cat population (12 females, 13 males) was observed almost daily for 6 years, at a location 40.53 degrees N and 74.29 degrees W. Cats were accustomed to twice-daily feeding. Oestrous behaviour was seasonal and started in early January, irrespective of climatic conditions, with peak levels of oestrous activities in late January and February. Of all 60 heat periods observed, and conceptions recorded, the percentage occurrence was 58 and 49 in the first quarter, and 29 and 33, 12 and 16 and 1 and 2 in the second, third and fourth quarter, respectively. Queens could be reliably identified as being pregnant by 31.5 +/- 5.82 days, and were subjected between days 36 and 57 of gestation to daily oral treatment with 5-15 micrograms cabergoline kg-1 placed on food. Treatments (n = 41) from days 36 +/- 6.17 to 40.8 +/- 6.96 resulted in abortion in all animals on day 40.5 +/- 6.19; if treatment started as late as day 48.5, and lasted 9 or more days, premature parturition occurred. As cabergoline had caused mammary gland regression within 36-48 h, litters could not be nursed and perished quickly. Five repeatedly aborted queens were subsequently allowed to go to term. Pregnancies, gestation length (64.5 days), parturitions, maternal care and lactations were normal. Of the 24 kittens born out of seven pregnancies, 16 were observed from 6 months to 3 years. Pubertal oestrus and first conceptions occurred at 189.9 days (range 150-214 days) and 212.0 days (155-277 days), respectively. Males were seen to achieve reproductive success in their third year only.