Research animals undergoing general anesthesia differ somewhat from animals normally encountered in clinical veterinary practice. Research animals usually are not ill or traumatized and generally are of the same species as the other animals within the study and have similar characteristics. Once a research model has been selected, consistency between animals is very important. Whether recovery and postoperative care are part of the experimental protocol or recovery is not intended, the concern for the management of anesthesia and care during the procedures should be identical, because it should be assumed that general anesthesia will affect whatever system is under study. The investigator should perturb the organ system under study only during a steady state of anesthesia (Soma and Klide, 1987; Some et al., 1988a); this minimizes the effect of changing depths of anesthesia on the animal and allows interpretation of data from the standpoint of a known, established baseline. Data from different laboratories often are not easily compared, and differences in methods of anesthesia can contribute to the difficulty. Ultimate goals of clinical and investigative anesthesia might differ, but the basic principles of good anesthetic techniques do not: maintain a depth of anesthesia that minimizes changes in physiologic function, blocks response to stimulation, and produces unconsciousness.

The development of inhalational anesthesia for both companion and laboratory animals has progressed a great deal in the last 20 years. It is beyond the scope of this section to describe the various methods and equipment that can be used for the administration of inhalational anesthesia to a broad range of animals, but information is readily available (Soma, 1971; Lumb and Jones, 1984; Hartsfield, 1987; Klide, 1989). Inhalational anesthesia can be administered by mask for a short procedure in most animals, but for longer periods of anesthesia the trachea should