The toxicity of 0·025% warfarin to wild house-mice (Mus musculus L.)

Abstract

1. Individually caged wild house-mice (Mus musculus L.) were fed 0·025% warfarin in a pinhead oatmeal/oil/sugar base. In all, 345 mice were tested for a fixed period ranging between 4 and 28 days.2. There was considerable variation in the susceptibility of individual mice. The lowest effective dosage was 26·1 mg./kg. of body weight in 4 days and the highest dosage survived was 1067·2 mg./kg. eaten over 21 days.3. The time required to obtain a 100% kill of house-mouse populations with 0·025% warfarin under field conditions is discussed.We thank the Director of the United States Department of the Interior, Fish and Wildlife Service, for permission to quote from the Quarterly Report of that Service.