Many poisons have been used against rodent pests. If baits are not well secured, they may be ingested directly by nontarget animal species (farm animals, pets, and wildlife). Sometimes, nontarget species may ingest recently poisoned rodent pests and develop relay or secondary poisoning. Occasionally, baits may be used maliciously or intentionally to kill either domestic animals or wildlife. This chapter discusses only the most commonly used rodenticides currently available in the market: anticoagulants, bromethalin, cholecalciferol, and zinc phosphide. Strychnine poisoning (see Strychnine Poisoning) is discussed separately.
Whenever a rodenticide exposure is suspected, owners should be asked history questions to determine the day and time of exposure, brand name and manufacturer of rodenticide, active ingredients and their concentration, package size, and the potential amount missing. The Environmental Protection Agency (EPA) registration number is the most accurate way to confirm identity of an active ingredient. There is no way to identify differing class by color, shape, or size of a bait.