Have you ever observed or seen photos of a horse in a hospital undergoing surgery that requires general anesthesia? After he’s anesthetized in a padded room he’s hoisted onto a table where, while the surgeon takes care of the procedure at hand, numerous assistants monitor the patient’s vital signs, ready to spring into action if any problems occur.
But when a horse undergoes a surgical procedure requiring general anesthesia in the field, the set-up is much less elaborate. At the 2013 Western Veterinary Conference, held Feb. 17-21 in Las Vegas, Nev., Robert Brosnan, DVM, PhD, an associate professor in the Department of Surgical and Radiological Sciences at the University of California, Davis, School of Veterinary Medicine, reviewed some points equine veterinarians must consider before implementing field anesthesia.
Pros and Cons
According to Brosnan, total intravenous anesthesia—a general anesthesia technique that uses a combination of agents given solely through a vein—is commonly used for field surgeries such as castrations. Benefits of intravenous anesthesia, he said, include that it requires minimal equipment, it avoids the need for patient transportation, it effectively renders a horse immobile and unconscious, and most currently used drugs allow horses to maintain a consistent blood pressure and recover quicker than from inhaled anesthesia.
But it’s not without drawbacks, he said. Horses become more likely to experience poor or prolonged recoveries with increasing length of anesthesia time. Most drugs used in field anesthesia are dependent on kidney and liver metabolism and excretion