| dc.description.abstract |
Cabergoline (CAB) is a potent dopamine agonist and an inhibitor of prolactin(PRL). In red foxes (Vulpes vulpes), a single oral doseof 100 g kg-1 CAB can cause abortions andpostnatal cub mortality from at least Day 21 of the 52-day pregnancy. Theabortifacient activity of CAB is owing to the suppression of PRL, which isessential for luteotrophic support in some eutherian species. Postnatal cubmortality probably results from a reduction in the development of the mammaryductile system, which is also partially dependant on PRL during pregnancy.This paper investigates the potential risks faced by non-target mammalianspecies that may consume CAB baits intended for fox control. Baiting with CABis proposed from 1 August until 1 October each year, to correspond with thetime that most vixens are pregnant in south-eastern Australia. Thirty-fourendemic mammals in south-eastern Australia (9 eutherians and 25 marsupials)are considered to be potentially bait-consuming (PBC) species. The percentageoverlap of pregnancy and birth periods for each PBC species was compared withthe duration of the proposed CAB baiting period. OnlyAntechinus (3 species) andSminthopsis leucopushave greater than 40%overlap, whereas overlap in endemic rodents ranges from 0% to22%. Overall, most PBC rodent populations appear to face little riskfrom CAB baiting, as their period of pregnancy does not overlap significantlywith the proposed CAB baiting period. The Antechinusspecies, Phascogale tapoatafa andDasyurus maculatus are the only PBC mammals that areseasonally mono-oestrous and are thus probably more susceptible to disruptionof breeding compared with polyoestrous species that may breed many times ayear. At a baiting density of 8 baits km-2,theoretical bait availability for small dasyurids, rodents and peramelids islow. This suggests a low potential for affecting these populations if CAB wasindiscriminate in affecting reproductive success in all mammal groups.Presently, studies in a limited range of marsupials suggest that, unlikeeutherians, the marsupial corpus luteum is independent of pituitary controland thus suppression of PRL is not likely to cause abortions in marsupials. Asyet, CAB has not been shown to be orally active in any PBC species other thanrodents and carnivores. Oral doses of CAB given post partum have not beenfound to affect lactation inSminthopsis crassicaudata,Trichosurus vulpecula,Macropus eugeniiandSetonix brachyurus. Further studies are required inorder to assess the potential for high doses of oral CAB to affect pre-partummammary development and early lactation post partum, especially in peramelidsand larger dasyurids. Highly target-specific baiting techniques, may eliminatemost PBC species from being exposed to CAB and these are briefly discussed. |
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