Anticoagulant rodenticides have been used for control of rodents (principally rats and mice in the UK) for over 50 years. UK and European legislation requires that manufacturers of poison baits provide efficacy data, including how many rodents are killed by a new bait formulation. As a consequence a small number of procedures are carried out in the UK every year which necessitate allowing animals to die from anticoagulant poisoning. There is a lag-time, of 4-6 days, from ingestion of bait to death associated with all anticoagulant rodenticides. This project aims to identify behavioural or biochemical markers during that lag-time that can be used to predict death or survival and allow humane methods to be used for ending the experiment before the animals die.