Evidence-based Decision Making in Equine Orthopedics: Options for Anesthetic Recovery Systems

Beyond the challenges equine surgeons are faced with regarding successful surgical repair of fractures and other orthopedic conditions are those associated with aiding the horse to recover from general anesthesia without major complication. As such, a variety of systems have been developed to aid horses through the recovery process. General anesthesia carries a considerable risk to even systemically healthy patients; a large-scale, multicenter study, “The Confidential Enquiry into Perioperative Equine Fatalities (CEPEF)” (Johnston GM 2002), reports the death rate of horses undergoing ‘non-colic’ surgery to be 0.9%, or 1 in 111 patients. Horses undergoing elective orthopedic procedures are typically systemically stable and general anesthesia is relatively short, while those presenting for major procedures such as fracture fixation and arthrodesis are frequently stressed, painful, exhausted, and subjected to being under anesthesia for long periods of time. The CEPEF reports that the mortality rate for horses undergoing general orthopedic surgery is equivalent to the overall rate, at 0.8%. Horses undergoing fracture repair suffered a mortality rate of 5%. The overall rate of fracture upon recovery was 0.2%, or 2/1000 cases. Observation of these data delineate three important points; 1) to show the general risk of anesthetic recovery to the musculoskeletal system, 2) to highlight the increased risk for patients suffering major orthopedic disease, and 3) to establish an inclusive and unbiased rate of mortality to which individual systems of recovery can be compared and evaluated. Systems for anesthetic recovery include both the physical and pharmacologic methods utilized to assist or modify the event. The vast majority of recoveries occur in padded stalls, with and without the use of a deep mattress. A variety of compressible floor surfaces are available to help provide both comfort and traction, and to minimize the forces placed on the musculoskeletal system while the horse is attempting to stand. Communication with a number of academic and private equine hospitals reveals that by far, most operations use padded stalls with head and tail ropes to perform hand assisted recoveries on their equine orthopedic patients. The largest and most recent study evaluating perioperative fatalities associated with general anesthesia at a private practice using a head and tail assisted recovery system reports a general mortality rate of 0.12% (21 out of 17,961 cases) (Bidwell LA 2007). Stratification of this data reveals a mortality rate of 0.05% in general orthopedic cases, and 0.5% in cases of fracture/arthrodesis. Of 8 cases that fractured on recovery (0.04%), none occurred in horses undergoing major orthopedic procedures.