Short-Term Anesthetic Tested on HorsesBy Kentucky Equine Research Staff · July 10, 2012
The use of anesthetics in horses is associated with some well-known problems. For long-term procedures, anesthetics administered by inhalation carry risks of low blood oxygen levels and problems with heart function. Anesthetics designed for short-term use have the same risks as well as increased muscle rigidity and tremors. An especially dangerous time after anesthesia has been administered is the critical period of recovery when the horse attempts to stand. Horses are easily frightened by unfamiliar sensations and surroundings, and they may injure themselves before they recover full coordination.
Alfaxalone is an anesthetic not commonly used in horses, though it is frequently used with small animals. A study conducted by the Rural Industries Research and Development Corporation Horse Program in Australia investigated the use of alfaxalone in foals and adult horses.
Trials were carried out with young (less than two weeks old) and older horses. Alfaxalone was administered intravenously for procedures including castration of young horses in the field. Blood pressure and oxygenation were monitored while the horses were anesthetized, and behavior during recovery was observed.
Alfaxalone was found to be effective and suitable for use in horses as a short-term anesthetic and also for long duration anesthesia when combined with isoflurane, an inhaled anesthetic. Alfaxalone was not suitable for use as the sole agent for long duration anesthesia. Because of its formulation, alfaxalone is more suited for use in foals. The larger volume necessary for efficacy in mature horses makes its use quite expensive. The researchers suggested that a more concentrated solution might be developed for administration to larger horses.