Teratology Studies in the Rat

The rat is the rodent species of choice for the regulatory safety testing of xenobiotics, such as medicinal products, food additives, and other chemicals. Many decades of experience and extensive data have accumulated for both general and developmental toxicology investigations in this species. The high fertility and large litter size of the rat are advantages for teratogenicity testing. The study designs are well defined in the regulatory guidelines and are relatively standardized between testing laboratories across the world. Teratology studies address maternal- and embryo-toxicity following exposure during the period of organogenesis. This chapter describes the design and conduct of a teratology study in the rat in compliance with the regulatory guidelines. The procedures for the handling and housing of the pregnant animals, the caesarean examinations and the sampling of fetuses for morphological examinations are described. The utility and design of preliminary studies and the inclusion of satellite animals in the main study for toxicokinetic sampling are discussed.