Emerging techniques, newer drugs and the continuing education of practitioners indicate that equine anesthesia is becoming less problematic.
Horses emerge from anesthesia faster, more safely and with fewer side effects. “The end point of anesthesia is typically to maintain the cardiovascular and respiratory functions as close as possible to normal physiological status,” said Bernd Driessen, DVM, Ph.D., associate professor of anaesthesia at the University of Pennsylvania College of Veterinary Medicine. “We know in horses that we cannot achieve that easily, but we are now able to stay at least within a 20 percent –to 30 percent range."
“More and more students have come of age in a time where sedation became a routine thing,” said Cliff Swanson, DVM, MS, associate professor of anesthesia at North Carolina State University College of Veterinary Medicine. “In the past, clients weren’t used to having their horses sedated for certain routine things [such as sheath cleaning and dental exams]. Now, it’s become more of a routine practice."
“This translates to better patient care because exams can be more thorough; there isn’t an overlay of anxiety with the owner; and the veterinarian can get on with assertive massaging of tissues,” he said.
This use of sedation also stems from better drugs, he said, in particular detomidine. Detomidine was first used in institutional practice and then recently translated into private practice.
“Detomidine has come into its own as the drug of choice among practicing vets,” Dr. Swanson said. “It is also a good analgesic, so you get the combined effect of sedation and pain control. Acepromazine was OK, but some horses can override the effect of the drug.”
Xylazine (same class as detomidine) is another popular sedative used in the field. It works with the same mechanism as detomidine but the behavioral modification and sedation is not as profound.
The No.1 inhalation anesthetic for years has been isoflurane. Many veterinarians give a continuous infusion of medetomidine (same class as detomidine) as an adjunct to isoflurane.
“This technique was first reported as a means of supporting blood pressure and smoothing recovery from isoflurane anesthesia,” Dr. Swanson said. “We began using it here at North Carolina State University after talking with Dr. Conny Gunkel who finished an anesthesia residency at the University of Florida, and joined us here in July."
Medetomidine is also a good analgesic, something that is lacking in isoflurane and sevoflurane. And the analgesia lasts a long time after the drug has worn off.
“We’ve also noticed that the recovery has been superb. Horses are stronger and better co-ordinated when they get up then as if they’ve just been given gas alone."
Swanson and his colleagues have used this continuous infusion with sevoflurane several times and continue to investigate the technique as a potential means of obviating the emergence problems with ultra-fast recovery from sevoflurane.
About the author
As an animal lover since childhood, Flossie was delighted when Mark, the CEO and developer of EquiMed asked her to join his team of contributors.
She enrolled in My Horse University at Michigan State and completed a number of courses in everything related to horse health, nutrition, diseases and conditions, medications, hoof and dental care, barn safety, and first aid.
Staying up-to-date on the latest developments in horse care and equine health is now a habit, and she enjoys sharing a wealth of information with horse owners everywhere..