Development of an anticoagulant resistance monitoring program for Philippine rats

The study sought to develop a suitable method for screening anticoagulant resistance; a test of compounds known to counter the development of resistant rats elsewhere was conducted on two local Philippine species. A 25-day no-choice feeding test using 0.025% warfarin bait for Rattus rattus mindanensis and a 30-day no-choice feeding test for R. argentiventer were established as a baseline method for future screening of warfarin-resistant rats, should resistance develop in these species. A rat would be considered resistant if it survived 14 days after the treated bait is withdrawn. Tests on bromadiolone at 0.005%, brodifacoum at 0.002%, and warfarin at 0.025% resulted in a similar mean number of days to death (5.6, 6.5, 5.9, respectively). The first two compounds have potential use in the Philippines to kill anticoagulant-resistant rats. (Author abstract, modified)