sufficient for surgical procedures. Urethane has been reported to be both mutagenic and carcinogenic, so it should be handled as a mild carcinogen, and animals anesthetized with it should not be allowed to recover (Flecknell, 1987).

Muscle relaxants do not provide relief from pain. They are used to paralyze skeletal muscles while an animal is fully anesthetized. If a procedure will cause no pain and the animal is properly ventilated, general anesthesia may be discontinued under carefully controlled conditions for specific neurophysiologic studies (Van Sluyters and Oberdorfer, 1991). Such use of muscle relaxants requires prior approval of an animal care and use committee, because acute stress is believed to be a consequence of paralysis in a conscious state. Table 5-10 lists does of the neuromuscular blocking agent pancuronium, which is commonly used in experimental animals. Klein (1987) has compiled an extensive review of neuromuscular blocking agents and their use in dogs, cats, pigs, horses, sheep, and calves. This