This laboratory guidebook provides step-by-step procedures that will aid in the dissection and collection of major organs and tissues of the most common species of small animals used in biomedical research. Through extensive use of photographs and illustrations, it guides dissectors through a complete necropsy of each species for the purpose of collecting organs and tissues routinely examined by pathologists. The techniques described enable technicians to perform necropsies on almost any mammal in a precise and logical sequence, and collect tissue properly to avoid diagnostic errors. Morphological differences among the various species are discussed.