Basic principles in selecting animal species for research projects.

One of the most important facets of biomedical research is selecting the species of laboratory animal best suited for a particular purpose. The four major categories of animal models are experimental, spontaneous, negative, and orphan. The experimental model is the one most frequently used, but each category has a place in medical research. Once the investigator has decided which type of model the project calls for, numerous other factors must be considered: ease of handling and surgical manipulation; size, docility, and body conformation; cost of the animal and its related supplies (food, bedding, and caging); the accessibility of superficial blood vessels; and the investigator's familiarity with the various species which are available. Among the biologic factors which should be considered are resistance to natural diseases, nutritional requirements, genotype, anatomy, physiology, and biochemistry.