rebreathing circuit and a ventilator-integrated anesthesia machine (Aestiva 5/7900; GE-Datex Ohmeda). Anesthetic maintenance was isoflurane in oxygen (1 to 2 L/min) targeting the end-tidal concentration of isoflurane (ET ISO ) between 1.4 and 1.6% as
infusion rates of remifentanil during anesthesia with equipotent concentrations of isoflurane in mechanically ventilated dogs and the possible correlation between opioid-induced changes in plasma vasopressin concentrations with some hemodynamic variables
anesthetic dose afforded by opioid receptor agonists is associated with reduced magnitude of cardiovascular depression in some species. 6,7
Fentanyl has been shown to reduce isoflurane MAC in rabbits 8 ; however, to our knowledge, whether this provides
Isoflurane is commonly used for inhalation anesthesia in dogs. Use of isoflurane often results in vasodilation, which can potentially cause hypotension. 1 Administration of premedication agents (tranquilizers, analgesics, and anxiolytics) before
allows comparison of anesthetic agents by potency and the ability to determine the MAC-sparing effects of other classes of drugs. Although isoflurane MAC among species is relatively consistent, deviations as high as 40% have been reported for some
anesthetic induction with diazepam and ketamine or xylazine and ketamine, with subsequent maintenance of anesthesia with isoflurane, in foals undergoing laparotomy and laparoscopy.
Materials and Methods
Animals —The University of Guelph Animal Care
Awake adult horses maintain an ICP of approximately 2 mm Hg that varies little with head position, 1 which suggests that CBF and CBV are highly regulated in the presence of fluctuating hydrostatic gradients. Isoflurane administration causes
the MAC of isoflurane; for example, MAC reductions as high as 25% can be safely achieved in dogs. 9,10 The clinical use of most NMDA antagonists, however, is hampered by short duration of action, low therapeutic index, and narrow separation between
–7 A low dose of acepromazine (0.05 mg/kg, IV) potentiated isoflurane-induced vasodilation but did not alter CO in dogs, 7 suggesting that the predominant cardiovascular effect of acepromazine is systemic hypotension.
Dexmedetomidine is a highly
Inhalation anesthesia is frequently used in avian patients for examination, diagnostic investigation, and surgical procedures, 1 as well as for research and management purposes. Traditionally, isoflurane has been the agent of choice for avian