32 AJVR, Vol 67, No. 1, January 2006 C ompared with anesthesia in humans and small ani- mals, anesthesia in horses is associated with much higher risk and has a morbidity rate as high as 1%. 1-3 Many of the perianesthetic problems that are observed in this species, such as poor recovery or myopathy fol- lowing anesthesia, are related to the development of hypotension and presumably inadequate tissue perfu- sion during anesthesia. 4-7 Anesthesia and surgery in horses have also been associated with the development of postoperative ileus, clinical signs of colic, and intesti- nal impaction. 8,9 In 1 retrospective study 8 of horses with impaction of the large colon, previous anesthesia and arthroscopic surgery were contributing factors in 19 of 147 cases. In another study 10 designed to determine prevalence and risk factors for development of ileus of the large intestine after surgery in horses, 10 of 85 (12%) horses developed signs of colic after orthopedic surgery. These delayed postoperative complications may have been associated with the choice of anesthetic agents, but this factor was not investigated in any detail. Although inhalation anesthesia is the most practical and effective means of management of prolonged anes- thetic episodes in many species, horses are particularly sensitive to the cardiopulmonary-depressant effects of inhalant anesthetics. 11-14 Received February 8, 2005. Accepted May 6, 2005. From the Department of Clinical Studies, Ontario Veterinary College, University of Guelph, Guelph, ON N1G 2W1, Canada. Dr. Durongphongtorn’s present address is Department of Veterinary Surgery, Faculty of Veterinary Science, Chulalongkorn University, Patumwan, Bangkok 10330, Thailand. Dr. Teixeira Neto’s present address is Department of Veterinary Surgery and Anesthesiology, Faculdade de Medicina Veterinaria e Zootecnia, Unesp, Botucatu, SP 14870-000, Brazil. Dr. Mirakhur’s present address is VIDO, University of Saskatchewan, 120 Veterinary Rd, Saskatoon, SK S7N 5E3, Canada. This manuscript represents a portion of a thesis submitted by the senior author to the Department of Clinical Studies, Ontario Veterinary College, University of Guelph for the Doctor in Veterinary Science degree. Supported in part by a grant from Equine Guelph; the Ontario Ministry of Agriculture, Food, and Rural Affairs; and the Ontario Horse Racing Industry Association. Presented in part as an abstract at the 8thWorld Congress of Veterinary Anesthesia, Knoxville, Tenn, September 2003. Address correspondence to Dr. McDonell. Comparison of hemodynamic, clinicopathologic, and gastrointestinal motility effects and recovery characteristics of anesthesia with isoflurane and halothane in horses undergoing arthroscopic surgery Sumit Durongphongtorn, DVM, DVSc; Wayne N. McDonell, DVM, PhD; Carolyn L. Kerr, DVM, DVSc, PhD; Francisco J. Teixeira Neto, MV, PhD; Kuldip K. Mirakhur, DVM, PhD Objective—To compare hemodynamic, clinicopatho- logic, and gastrointestinal motility effects and recov- ery characteristics of halothane and isoflurane in hors- es undergoing arthroscopic surgery. Animals—8 healthy adult horses. Procedure—Anesthesia was maintained with isoflu- rane or halothane (crossover study). At 6 intervals dur- ing anesthesia and surgery, cardiopulmonary vari- ables and related derived values were recorded. Recovery from anesthesia was assessed; gastroin- testinal tract motility was subjectively monitored for 72 hours after anesthesia. Horses were administered chromium, and fecal chromium concentration was used to assess intestinal transit time. Venous blood samples were collected for clinicopathologic analyses before and 2, 24, and 48 hours after anesthesia. Results—Compared with halothane-anesthetized horses, cardiac index, oxygen delivery, and heart rate were higher and systemic vascular resistance was lower in isoflurane- anesthetized horses. Mean arterial blood pressure and the dobutamine dose required to maintain blood pressure were similar for both treatments. Duration and quality of recovery from anesthesia did not differ between treat- ments, although the recovery periods were somewhat shorter with isoflurane. After isoflurane anesthesia, gas- trointestinal motility normalized earlier and intestinal tran- sit time of chromium was shorter than that detected after halothane anesthesia. Compared with isoflurane, halothane was associated with increases in serum aspar- tate transaminase and glutamate dehydrogenase activi- ties, but there were no other important differences in clin- icopathologic variables between treatments. Conclusions and Clinical Relevance—Compared with halothane, isoflurane appears to be associated with better hemodynamic stability during anesthesia, less hepatic and muscle damage, and more rapid return of normal intestinal motility after anesthesia in horses undergoing arthroscopic procedures. ( Am J Vet Res 2006;67:32–42) CO Cardiac output DO 2 Delivery of oxygen IPPV Intermittent positive-pressure ventilation SVR Systemic vascular resistance CVP Central venous pressure MAP Mean arterial blood pressure LiDCO Lithium chloride dilution CO SAP Systolic arterial blood pressure DAP Diastolic arterial blood pressure CaO 2 Arterial oxygen concentration CI Cardiac index Unauthenticated | Downloaded 08/14/22 01:27 AM UTC