Bull Vet Inst Pulawy 51, 93-96, 2007 CARDIOPULMONARY EFFECTS OF ACEPROMAZINE-KETAMINE ADMINISTRATION IN THE SHEEP ALI BANIADAM, FEREIDOON SABERI AFSHAR, AND MOHAMMAD REZA BAKRANI BALANI 1 Department of Clinical Sciences, 1 Graduated of Veterinary Medicine, Faculty of Veterinary Medicine, Shahid Chamran University, 61355-145 Ahvaz, Iran baniadam@scu.ac.ir Received for publication August 24, 2006. Abstract The effects of acepromazine-ketamine on the heart rate, arterial blood pressure, respiratory rate, blood gases, arterial blood pH, and temperature were investigated in six healthy sheep. Ketamine (11 mg/kg i.v.) was given 15 min after administration of acepromazine (0.05 mg/kg i.m.) A catheter was placed in the carotid artery for arterial blood sampling and recording of mean arterial blood pressure. All parameters were evaluated before the administration of acepromazine and at 5, 15, 30, 45, and 60 min following the injection of ketamine. The arterial blood pressure was recorded in 30 s after the injection of ketamine as well. The heart rate decreased significantly at minutes 15, 30, 45, and 60. The mean arterial blood pressure declined significantly at 30 s and 45 min. The mean respiratory rate decreased significantly at 45 and 60 min. PaO 2 decreased significantly at 5, 15, and 45 min, and PaCO 2 increased at 5 min. The pH values decreased significantly at 5, 15, and 30 min. The body temperature decreased significantly at all points in time. The data showed that the combination of acepromazine-ketamine caused an inhibition of the cardiovascular system. This combination is responsible for little distributed ventilation, decreased PaO 2 , increased PaCO 2 , decreased pH values, and a declined in body temperature in the anaesthesia period in sheep. Key words: sheep, anaesthesia, acepromazine, ketamine, cardiovascular system, blood gas. Ketamine HCl, a phenylcyclidine analogue, is a short-acting non-barbiturate general anaesthetic, which was used in non-human primates in the sixties (15, 17). It is 2-(o-chlorophenyl)-2-(methylamine)-2- cyclohexanone hydrochloride (18). It selectively inhibits areas of the central nervous system, and stimulates simultaneously other systems (15, 17). Because of its selective action on tissues of the central nervous system, ketamine differs markedly from other established general anaesthetic agents. It has been used successfully as a general anaesthetic agent in a variety of domestic animals, including cats, dogs, horses, and sheep (17). Ketamine has been proved an acceptable anaesthesia for sheep and goats, and can be used on its own, but muscle tone and trembling makes the effect unpleasant, although the analgesia appears to be good (13, 16). The administration of acepromazine in combination with ketamine has distinct advantages. Acepromazine reduces the dosage of ketamine needed for a given period of analgesia, and increases the degree and duration of muscle relaxation, and prevents reflex movements of the limbs. Acepromazine prolongs standing and full recovery times, however (18). The induction of general anaesthesia is a transition from conscious state to unconsciousness. The body’s systems are usually placed immediately in an unstable state, and undesirable responses from the cardiovascular and respiratory systems may be observed (15). Phenothiazine tranquilisers, such as acepromazine, will markedly decrease systemic blood pressure and heart rate. Dissociative agents, such as ketamine, will substantially increase the heart rate, systemic blood pressure, and a decrease in cardiac contractility (12). In this study, the effect of acepromazine-ketamine on arterial blood pressure, blood gases, pH, heart rate, respiration, and temperature was investigated. Material and Methods Six one-year-old Iranian sheep, with an average weight of 22.5 kg, were used. The animals were housed in the teaching hospital of the Faculty of Veterinary Medicine of Shahid Chamran University under conventional conditions. The feed was withheld from all the sheep for 24 h prior to the administration of drugs, but access to water was allowed ad libitum. The sheep were positioned in a left lateral recumbency on the table, and the lateral surface of the neck was prepared for aseptic surgical intervention. After local anaesthesia, a 5 cm right lateral incision was made to isolate the right lateral carotid artery. The artery