Control of fertility in the red fox (Vulpes vulpes):: effect of a single oral dose of cabergoline in early pregnancy

Single oral doses of 100 mug kg(-1) cabergoline (CAB) were previously found to affect the reproductive success of silver fox (Vulpes vulpes) vixens from Day 28 post insemination (PI) onwards by causing abortions and postnatal mortality. The present trial investigated the effect of a single oral dose of 100 mug kg(-1) CAB given to farmed silver fox vixens at 7, 14, 21 or 28 days PI. Six vixens were dosed with CAB at each day PI and abortions, total post-partum litter loss and the combined effects of both were compared with a group of vixens that received a placebo and a control group of vixens that received no treatment. No significant difference existed between the placebo and control groups in the incidence of abortion, postnatal litter loss and litter size at 3 weeks post partum. Overall, a significantly higher frequency of abortions were detected in vixens dosed with CAB (6/24) compared with the combined placebo and control (0/41) groups (P<0.01). Cabergoline administration was significantly associated with complete litter loss (P<0.01) and the combined effects of abortion and litter loss (P<0.001). Oral CAB significantly reduced the reproductive success of vixens when given at Day 21 and Day 28 PI, but not at Day 7 and Day 14 PI.