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).

Use of Skeletal Muscle Relaxants

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

TABLE 5-10 Doses of Pancuronium in Domestic Species

Species

Dose, mg/kg

Duration, minutes

Anesthetic

Reference

Calf

43 ± 9a

43 ± 19a

Halothane-O2

Hildebrand and Howitt, 1984

Sheep

5.0 ± 0.61

21 ± 2.5

Halothane-O2

Klein et al., 1985;

Cass et al., 1980

 

0.15/min

steady state

 

 

Horse

82 ± 7.3

20–35

Halothane-O2

Klein et al., 1983

Pony

125 ± 20a

16

Halothane-O2

Manley et al., 1983

Pig

50

 

Thiopental- N2O-O2, or ketamine

Denny and Lucke, 1977

 

10

 

 

Lumb and Jones, 1984

Dog

22 ± 3

108 ± 10

Halothane

Booij et al., 1980

Cat

20

15 ± 2a

Halothane-α-chloralose

Hughes and Chapple, 1976

 

22

14 ± 2

Pentobarbital

Durant et al., 1980

 

34

8.8 ± 2.3

α-Chloralose-pentobarbital

Durant et al., 1979

a Mean ± standard deviation.

SOURCE: Modified from Klein, 1987.



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