opioid might facilitate management during the immediate postanesthetic and postoperative period.


Common Examples

Azaperone (Stresnil® and droperidol.

Clinical Use

Azaperone is approved for swine, in which it is used mainly to prevent fighting and as a preanesthetic agent. It is a more potent sedative and less hypotensive than the phenothiazines, but has no analgesic effect (Flecknell, 1987). Droperidol is incorporated with fentanyl in Innovar-Vet® (see Chapter 5).

Pharmacologic Effect

Like the phenothiazines, butyrophenones exert general sympatholytic activity that probably accounts for many of their common properties. Butyrophenones seem more likely to produce extrapyramidal signs of rigidity, tremors, and catalepsy.

Dose Recommendations

In pigs, azaperone at 2.2 mg/kg intramuscularly produces sedation, but has no analgesic effect. Combined at 5 mg/kg with metomidate (10 mg/kg) intramuscularly, it produces sedation and analgesia suitable for minor surgical procedures (Flecknell, 1987). In horses, azaperone administered intravenously at 0.22–0.44 mg/kg might cause excitement and extrapyramidal effects and is not recommended (Muir et al., 1989).


Common Examples

Diazepam (Valium®), zolazepam, and midazolam (Versed®).

Clinical Use

Benzodiazepines induce a mild calming effect and have therapeutically useful anticonvulsant, muscle-relaxant, and hypnotic effects in animals; they have no analgesic activity. They are commonly used with analgesic drugs (e.g., xylazine, opioids, or ketamine) to enhance muscle relaxation.

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement