Toxicology

Abstract

The rat is one of the most important animal models in toxicology. This chapter describes the types of toxicological studies and provides information about variables that must be considered in designing toxicology experiments such as rat strain, diet, water quality, intestinal flora, and environmental enrichment. In acute toxicity testing, a single dose of a test compound is given once to ascertain the adverse effects on the animal. Range-finding tests with a small number of animals are usually used to determine the relative lethality of a compound. Then larger numbers of animals are used to determine relative toxicity. LD50 is a dose that is lethal to half of the animals on study. In LD50 testing, several dose levels of the test compound are used, with one dose per group of animals, and the testing is performed in replicates. Typical LD50 tests require 100 animals or more. LD50 determinations provide the median lethal concentration of a test compound and information in terms of the dose-response relationship, clinical signs of toxicity, and gross and histopathologic findings.