The idea that Friesian horses may be more at risk for complications related to anesthesia is a common misconception. The primary risks of equine anesthesia related complications are actually associated with key factors, such as the weight, age and health of the horse and the type of surgery, rather than the specific breed of horse. Heavier horses (1500 lbs or larger), as well as heavily muscled horses, are more likely to experience complications or die from general anesthesia than lighter horses. Weight related anesthesia complications are associated with muscle or nerve damage that can occur with the lack of pressure and/or lack of blood flow to critical areas of the body. The consequences of weight related anesthesia complications vary depending on the severity of damage. Rarely, the horse is unable to stand during recovery and this can be fatal. In most cases, weight related anesthesia complications can be managed using appropriate positioning and padding of the patient during anesthesia and ensuring blood pressure is supported.
Aside from weight, there are other influences which can contribute to greater risk when horses undergo general anesthesia. Age is an important consideration, with older horses incurring greater risk of mortality from anesthesia. Also, horses with underlying illness have less effective organ function and are more susceptible to the adverse effects of the anesthetic drugs. More complex surgeries, like a fracture repair, require significant time to complete which increases the risk of complications such as muscle damage, long bone fracture and death. In general, orthopedic surgery carries a 10-fold greater risk of anesthesia related mortality. Additionally, some emergency related surgeries (cesarean section, colic and orthopedic trauma) carried higher risks. While factors such as the weight or age of the horse cannot be controlled, the one risk factor veterinarians can control is time. By controlling the duration of time under general anesthesia some risks can be reduced. Pre-op efficiencies, such as surgical site preparation, can yield great time savings. Additionally, administrative efficiencies such as having staff and equipment on time and well organized in the operating room can yield time savings. The experience of the surgeon and surgical staff can also greatly contribute to reduced surgery time.
So, what can you do to minimize your Friesian’s risk in the event they require general anesthesia? Talk to your veterinarian and discuss the risks associated with anesthesia, including your Friesian’s weight. Ask what procedures the surgeon and staff will take to mitigate risks of anesthesia related complications. The more information you have, including understanding your individual horse’s risk factors, the better prepared you will be.
References:
Risk Factors of Anesthesia-Related Mortality and Morbidity in One Equine Hospital: A Retrospective Study on 1,161 Cases Undergoing Elective or Emergency Surgeries. C. Laurenza, L. Ansart & K. Portier, 2019.
Reducing risk in equine anesthesia part 1: recognizing risk factors and addressing common complications. K. Loomes, 2019.
Equine Anesthesia (Second Edition): Monitoring and Emergency Therapy. W. Muir & J. Hubbell, 2009.