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Discovery: Drug Combo Improves Safety of Equine Anesthesia

December 16, 2011

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Robert J. Brosnan , DVM, PhD, is an associate professor in the Department of Surgical and Radiological Sciences; his professional interests include mechanisms of anesthetic action cardiopulmonary effects of anesthesia.

The anesthesia team in the Large Animal Clinic, led by faculty member Robert Brosnan, DVM, PhD, DACVA, have published "Anesthetic induction with guaifenesin and propofol in adult horses," in the American Journal of Veterinary Research. 

The researchers used a combination of guiafenesin & propofol to induce horses for general anesthesia, which reduced adverse reactions that can occur during induction when propofol is used alone. Propofol may be a superior anesthetic option for certain horses and generally results in a smoother recovery from general anesthesia.

Brosnan offers this summary of the issues of safe and effective anesthesia in horses: 

Anesthesia is associated with a much greater risk in horses than in dogs, cats, or people. One reason for this difference is that there are fewer anesthetic drug options available in horses, and some anesthetics are associated with severe side effects not commonly seen in other species.

Propofol is an injectable anesthetic routinely used in animals and humans, and it has important desirable properties that are lacking in other agents. 

However, whereas propofol produces a smooth and rapid transition to unconsciousness in humans and most animal species, this same drug in horses causes violent paddling movements in the front and back legs that can result in injury to both the horse and the people around it. Although propofol offers many potential advantages, this dangerous paddling has until now made its routine use for anesthetic induction in horses impractical and unsafe.

Researchers at U.C. Davis School of Veterinary Medicine have discovered a way to reliably prevent limb paddling following propofol anesthetic inductions in horses by using the drug guaifenesin. With this new technique, transition to anesthesia can be achieved as smoothly and safely as in other species. 

Equine veterinarians can now take advantage of propofol's desirable properties as an anesthetic induction agent in horses, such as rapid elimination and improved recovery quality. This technique will also allow propofol to be used in horses that have conditions for which other anesthetic choices are undesirable or harmful.


Publication information:

Am J Vet Res. 2011 Dec;72(12):1569-75.
Anesthetic induction with guaifenesin and propofol in adult horses.
Brosnan RJ, Steffey EP, Escobar A, Palazoglu M, Fiehn O.