不同麻醉药对成年蛋鸡麻醉效果及行为的影响

为筛选适用于鸡的麻醉药,研究将戊巴比妥钠、舒泰、陆眠宁、丙泊酚及舒眠宁应用于蛋鸡,观察并记录麻醉诱导时间、麻醉维持时间和麻醉苏醒时间;检测蛋鸡进入麻醉期后的心率、每分钟呼吸次数、体温、眼睑反射、镇静效果、痛觉反射和肌肉松弛度;观察分析麻醉苏醒6h后紧张性静止不动时间和啄食频率。结果显示:0.07mL/kg舒眠宁和0.18mL/kg舒泰的麻醉起效时间、麻醉效果、安全性等与戊巴比妥钠接近,但两种药物到麻醉后期肌肉松驰效果均变差;丙泊酚麻醉起效迅速、麻醉维持时间较短,苏醒快,镇静和镇痛效果较好,肌肉松驰效果中等;陆眠宁不能达到100%麻醉效果,且麻醉用量大,麻醉起效慢,镇静和肌肉松驰不确实,有明显的呼吸抑制作用。研究结果表明0.07mL/kg舒眠宁和0.18mL/kg舒泰可用于兽医临床教学或科学研究中的蛋鸡麻醉。     

舒泰50麻醉对家兔相关生理生化指标影响及家兔血流动力学变化机制的研究

为了探究舒泰50麻醉对家兔相关生理生化指标影响及家兔血流动力学变化机制,试验取12只健康家兔,按体重肌肉注射0.1 mL/kg舒泰50,建立舒泰50麻醉模型,并记录家兔麻醉相关时间(诱导、维持、苏醒和总麻醉时间).对舒泰50麻醉前(0分钟)、麻醉后5,10,15,20分钟及苏醒后10分钟的收缩压(SAP)、舒张压(DA...     

舒眠宁对灵(猩)的麻醉效果观察

9只灵(猩)不使用麻醉前用药,经静脉注射舒眠宁,观察其麻醉诱导时间、维持麻醉时间、苏醒时间、心率、血氧饱和度、呼吸数、收缩压、舒张压和直肠温度,评价其麻醉效果.结果显示:诱导、维持麻醉、苏醒时间分别为(33.11±3.76)s、(23.00±5.83) min、(15.00±5.00)min；对呼吸数影响较大,对心率、血氧饱和度、血压和体温在大部分时段影响较小；麻醉过程平稳,无明显副作用.     

速眠新Ⅱ与舒泰50混合麻醉最佳配比及用量的探索

为了探索速眠新Ⅱ与舒泰50联合用药的最佳混合比例及用药剂量,试验将66只新西兰大白兔随机分为11组,3种不同的用药比例(速眠新Ⅱ与舒泰50的比例分别为3∶7、5∶5、7∶3)与3种不同的用药剂量(0.05 mL/kg、0.07 mL/kg、0.10 mL/kg)组成9个试验组,同时设两组单纯用药的对照组,每组试验兔6只,对11组兔分别用不同混合比例及不同剂量的速眠新Ⅱ与舒泰50混合液进行麻醉,比较各组兔在不同用药比例和剂量下的麻醉相关时间(诱导时间、维持时间、苏醒时间、麻醉总时间)、相关生理指标(体温、呼吸频率、心率及眼睑反射)和疼痛程度等。结果表明:6组相比于其他8个试验组和2个对照组麻醉相关指标最好,生理影响最小。说明速眠新Ⅱ与舒泰50混合体积比为5∶5,按0.10 mL/kg剂量麻醉时可以达到理想的临床麻醉要求,具有临床推广应用价值。     

犬微量注射泵持续静脉输注舒眠宁的麻醉效果研究

舒眠宁是本实验室研制的一种新型犬、猫用复方麻醉剂,在犬肌肉及静脉推注麻醉的基础上,用微量注射泵持续静脉输注舒眠宁,研究其对犬心血管、呼吸系统及麻醉效果的影响。选用成年杂种犬8只,无麻醉前用药,先静注舒眠宁0.05 mL/kg,然后接微量注射泵持续输注,其输注速率为0.1 mL/(kg.h),持续输注1 h。每隔5 min测定心率、呼吸频率、体温、血压、血氧饱和度、呼气末二氧化碳分压、血气指标,评分镇静、镇痛、肌松效果。结果表明:舒眠宁单次给药后起效迅速,微量注射泵持续输注麻醉平稳,各时相呼吸数、体温、血氧饱和度、呼气末二氧化碳分压、血气指标与麻醉前比较差异不显著(P>0.05),心率、血压个别时相差异显著(P<0.05),但均在正常生理范围内;在整个输注过程中,试验犬镇静、镇痛、肌松效果好。说明舒眠宁单次麻醉起效快,持续微量静脉输注麻醉平稳,外科麻醉期长,苏醒快,对心血管、呼吸系统影响小,未见明显不良反应。     

速眠新Ⅱ与舒泰复合麻醉剂对比格犬麻醉效果分析

为了探索速眠新Ⅱ与舒泰复合麻醉剂对比格犬的麻醉效果,选用健康比格犬20只,用速眠新Ⅱ(0.6mg/kg)与舒泰(0.75mg/kg)混合肌注诱导麻醉,30min后给予该混合制剂静脉维持麻醉(每小时速眠新Ⅱ0.2mg/kg,舒泰0.3mg/kg),随麻醉时间延长逐渐减量。结果显示,速眠新Ⅱ与舒泰复合麻醉剂,诱导麻醉迅速,维持麻醉效果安全、稳定,镇痛及肌松等效果良好,麻醉期间能保证动物的正常心肺功能。试验表明该复合麻醉剂是一种理想的麻醉剂,能满足各种外科手术操作需求。     

舒泰与右美托咪定或丙泊酚复合对兔麻醉效果的比较

为了比较舒泰与右美托咪定或丙泊酚复合对新西兰兔麻醉效果,将12只健康成年新西兰兔分为2组,每组6只,其中舒泰右美组静脉注射舒泰50(15 mg/kg)和盐酸右美托咪定(0.02 mg/kg),舒泰丙泊酚组静脉注射舒泰50(15 mg/kg)和丙泊酚(6 mg/kg),对2种麻醉方案进行麻醉指标、生理生化指标监测。结果显示：麻醉时期,舒泰右美组诱导期(2.6±0.4)min,麻醉期(31.2±5.2)min,苏醒期(8.5±2.6)min;舒泰丙泊酚组诱导期(3.6±2.24)min,麻醉期(50±5.48)min,苏醒期(3.8±1.31)min。镇静镇痛肌松效果显示,麻醉中舒泰右美组好于舒泰丙泊酚组。舒泰右美组体温、心率下降明显,舒泰丙泊酚组呼吸抑制明显;2组肝功能指标无显著变化、肾功能指标有一定影响。结果表明,舒泰右美复合方案麻醉诱导期短,对新西兰兔体温和心率有抑制作用,对肾功能有一定影响;舒泰丙泊酚复合方案麻醉期长,呼吸抑制明显,对肾功能影响较小。2种方案麻醉效果良好,均可用于兔的麻醉。     

噻拉嗪复合舒泰对长白猪的麻醉效果观察

为评价噻拉嗪复合舒泰对长白猪的麻醉效果,试验选取10头长白猪,肌肉注射噻拉嗪1.0 mg/kg和舒泰50 8.0 mg/kg,连续监测全麻过程中猪只的麻醉状态、镇痛、镇静和肌松效果。结果表明:给药后(6±1)min全部猪只进入麻醉状态,麻醉可维持(23±1) min,苏醒期为(32±2)min;在麻醉期全程中猪只的镇痛、镇静和肌松效果良好。说明给予1.0 mg/kg的噻拉嗪和8.0 mg/kg的舒泰50对长白猪麻醉时诱导迅速,维持时间长,苏醒平稳,可用于猪外伤处置、脐疝、腹壁疝等中型手术的麻醉保定。     

舒泰与盐酸右美托咪定对兔复合麻醉效果的研究

为了探讨用舒泰与盐酸右美托咪定对实验兔进行复合麻醉在小型手术和试验中使用的可行性,试验在兔的耳缘静脉分别按体重注射舒泰(0.3 mL/kg)和盐酸右美托咪定(0.02 mL/kg),记录麻醉诱导时间、麻醉时间、苏醒时间,麻醉前(0分钟)及麻醉后5,10,15,20,25,30分钟的镇痛、镇静和肌松作用效果及体温(T)、呼吸频率(RR)、心率(HR)、血氧饱和度(SpO₂)等生理指标;分别在麻醉前(0小时)及麻醉后1,2,24小时时耳缘静脉采血,测定血常规和血液生化指标。结果表明：该复合麻醉方案的麻醉诱导时间为(2.6±0.4)min,麻醉时间为(31.2±5.2)min,苏醒时间为(8.5±2.6)min。麻醉后5分钟大多数实验兔进入良好的镇静状态,并持续至麻醉后第25分钟;麻醉后5分钟大多数实验兔进入良好的镇痛状态,并持续至麻醉后第20分钟;麻醉后15分钟大多数实验兔肌松状态良好,并持续至麻醉后第20分钟。与麻醉前相比,实验兔T、RR、HR、SpO₂均呈现先下降后上升趋势。T在麻醉后10分钟显著下降(P<0.05);随后逐渐升高,基本...     

右美托咪啶与舒泰对圈养虎麻醉效果的观察

为了评估右美托咪啶与舒泰(替来他明和唑拉西泮合剂)对虎的麻醉效果,17只虎(4只孟加拉虎、4只华南虎和9只东北虎)按0.025~0.038 ml/kg的剂量肌肉注射进行麻醉,最终以阿替美唑进行苏醒,分别对诱导、麻醉及苏醒效果进行观察和评分。右美托咪啶和舒泰联合用药对虎的诱导期为(12.24±4.56)min,侧卧姿势进入麻醉期,平均诱导效果判定为1(极好),麻醉期间体温为(39.4±0.95)℃,较正常体温高;呼吸频率为(7.50±2.56)次/min,下降极显著,血氧饱和度为(87.32±8.43)%,与麻醉前相差不大。平均麻醉效果判定为4~5(中度麻醉至外科麻醉水平),静脉注射颉颃药阿替美唑后,苏醒时间(8.31±3.87)min,平均麻醉效果为2~3(一般,好),苏醒过程中所有虎出现较明显的共济失调或不协调的现象,苏醒后6 d内未见神经症状及其他副作用。右美托咪啶与舒泰联合用药对健康的虎是一种有效的麻醉药物,但苏醒过程中可能出现共济失调现象。     

The pharmacokinetics and pharmacodynamics of alfaxalone in cats after single and multiple intravenous administration of Alfaxan® at clinical and supraclinical doses

This study aimed to determine the pharmacokinetic parameters and pharmacodynamics of alfaxalone in a 2‐hydroxypropyl‐β‐cyclodextrin alfaxalone formulation (Alfaxan^®, Jurox Pty Ltd, Rutherford, NSW, Australia) in cats after single administration at clinical and supraclinical dose rates and as multiple maintenance doses. First, a prospective two‐period cross‐over study was conducted at single clinical and supraclinical doses. Second, a single group multiple dose study evaluated the effect of maintenance doses. Eight (five female and three male) domestic cats completed the cross‐over experiment and six female cats completed the multiple dose study. In the first experiment, alfaxalone was administered intravenously (IV) at 5 or 25 mg/kg with a washout period of 14 days. In the second experiment, alfaxalone was administered IV at 5 mg/kg followed by four doses each of 2 mg/kg, administered at onset of responsiveness to a noxious stimulus. Blood was collected at prescribed intervals and analysed by LCMS for plasma alfaxalone concentration. Noncompartmental pharmacokinetics were used to analyse the plasma alfaxalone data. The plasma clearance of alfaxalone at 5 and 25 mg/kg differed statistically at 25.1 and 14.8 mL/kg/min respectively. The elimination half lives were 45.2 and 76.6 min respectively. Alfaxalone has nonlinear pharmacokinetics in the cat. Nevertheless, for cats dosed with sequential maintenance doses, a regression line through their peak plasma concentrations indicated that there was no clinically relevant pharmacokinetic accumulation. The duration of nonresponsiveness after each maintenance dose was similar at approximately 6 min, indicating a lack of accumulation of pharmacodynamic effect. The cardiovascular and respiratory parameters measured in cats after administration of the labelled doses of Alfaxan^® were stable. In conclusion, the pharmacokinetics of alfaxalone in cats are nonlinear. At clinical dose rates, however, neither alfaxalone nor its effects accumulated to a clinically relevant extent. Further, in the un‐premedicated cat the induction and maintenance of surgical anaesthesia was free of untoward events after a dose of 5 mg alfaxalone/kg body weight followed by four sequential doses of 2 mg/kg as needed (i.e., approximately 7 to 8 mg/kg/h).     

赛拉嗪-咪达唑仑复合麻醉剂对山羊大脑和海马NO/cGMP信号转导系统及神经递质的影响

旨在研究赛拉嗪复合咪达唑仑对山羊的麻醉效果,并检测中枢神经递质及NO/cGMP信号转导系统的变化,为山羊麻醉提供新的方法,并明确该复合制剂的全身麻醉作用机理.山羊肌内注射复合麻醉剂1.31 mL·kg-1,对照组注射生理盐水,观察动物的行为学变化,监测山羊的生理指标并评估麻醉效果,分别于麻醉诱导期、麻醉期、恢复Ⅰ期、恢...     

Pharmacokinetics of oxymorphone in cats

Siao, K. T., Pypendop, B. H., Stanley, S. D., Ilkiw, J. E. Pharmacokinetics of oxymorphone in cats. J. vet. Pharmacol. Therap. 34 , 594–598. This study reports the pharmacokinetics of oxymorphone in spayed female cats after intravenous administration. Six healthy adult domestic shorthair spayed female cats were used. Oxymorphone (0.1 mg/kg) was administered intravenously as a bolus. Blood samples were collected immediately prior to oxymorphone administration and at various times up to 480 min following administration. Plasma oxymorphone concentrations were determined by liquid chromatography–mass spectrometry, and plasma oxymorphone concentration–time data were fitted to compartmental models. A three‐compartment model, with input in and elimination from the central compartment, best described the disposition of oxymorphone following intravenous administration. The apparent volume of distribution of the central compartment and apparent volume of distribution at steady state [mean ± SEM (range)] and the clearance and terminal half‐life [harmonic mean ± jackknife pseudo‐SD (range)] were 1.1 ± 0.2 (0.4–1.7) L/kg, 2.5 ± 0.4 (2.4–4.4) L/kg, 26 ± 7 (18–38) mL/min.kg, and 96 ± 49 (62–277) min, respectively. The disposition of oxymorphone in cats is characterized by a moderate volume of distribution and a short terminal half‐life.     

The optimal intravenous dose of midazolam after intravenous ketamine in healthy awake cats

The effects of intravenous administration of variable-dose midazolam (0, 0.05, 0.075, 0.1, 0.3 and 0.5 mg/kg) and ketamine (3 mg/kg) were studied in twenty-four healthy unmedicated cats from time of administration until full recovery. End-points were chosen to determine the optimal dose to allow a short period of restraint without noxious stimuli, a short period of restraint with noxious stimuli and endotracheal intubation. Recovery characteristics, as well as undesirable behaviours observed during recovery, were also recorded. The dose of midazolam to achieve lateral recumbency with head down was found to be 0.016 mg/kg in 50% of the population (ED₅₀) and 0.054 mg/kg in 95% (ED₉₅) of the population. A midazolam dose of 0.286 mg/kg was required to prevent conscious perception of a stimulus to the ulnar nerve in 50% of the population and 0.652 mg/kg in 95% of the population. The ED₅₀ and ED₉₅ of midazolam required to prevent swallowing in response to a laryngoscope placed on the back of the tongue were found to be 0.265 mg/kg and 0.583 mg/kg, respectively. The ED₅₀ doses of 0.265 mg/kg for intubation and 0.286 mg/kg for restraint with noxious stimulation were close to the tested dose of 0.3 mg/kg. At that dose, the lack of responses lasted 3.67 ± 2.27 min for laryngoscope and 2.50 ± 2.20 min for ulnar nerve stimulation, with recovery to walking with ataxia taking 41.50 ± 15.18 min and complete recovery taking 3.6 ± 1.3 h. The predominant behavioural pattern during recovery was found to be normal, but some cats also exhibited abnormal behavioural patterns. Nine of the twelve cats exhibited an abnormal arousal state, with 4 being restless and 5 being sedated. Seven of the twelve cats exhibited an abnormal behaviour when approached, with three of the cats being more difficult to approach and four of the cats being easier to approach. Eight of the twelve cats exhibited an abnormal behavioural pattern when restrained, with the cats equally divided between more difficult and easier to restrain. Five of the twelve cats vocalized more during the recovery. The ED₅₀ of 0.042 mg/kg to induce chemical restraint without a noxious stimulus is close to the tested dose of 0.05 mg/kg. At that dose, cats remained lateral with head down for 5.49 ± 4.02 min, took 25.96 ± 5.77 min to walk with ataxia and 1.7 ± 0.4 h for complete recovery. The predominant behavioural patterns during recovery were normal, with several cats exhibiting some abnormal patterns. Two cats were sedated, one cat was more difficult to approach, one cat was easier to restrain and three cats were more vocal.     

Quantitative characteristics of anesthetic induction with and recovery from isoflurane and sevoflurane in cats

Isoflurane (ISO) is the most commonly administered feline inhalant anesthetic in North America. A newer agent, sevoflurane (SEVO), may provide faster induction and recovery from anesthesia based on its physical characteristics. Accordingly, we compared some induction and recovery characteristics of ISO and SEVO in healthy cats. Six female DSH cats (17.9 ± 9.0 (mean ± SD) months, 3.7 ± 0.3 kg) received four randomly assigned treatments: ISO for 1 hour (IS), SEVO for 1 hour (SS), ISO for 5 hours (IL), and SEVO for 5 hours (SL). Anesthesia was induced in a chamber into which ISO or SEVO was delivered at 2.7 times the individual's MAC (determined previously) in 6 L minute^?1 O₂. Measured (Rascal II, Ohmeda) anesthetic concentration was reported after correction using a multiple gas, standard‐defined calibration curve. For induction, time (seconds) from introduction of inhalant to onset of incoordinated movement (IM), recumbency with movement (RM), recumbency without movement, loss of pedal reflex (PD), and intubation (ET) were recorded. Following intubation, anesthesia was maintained for the required time at 1.25 times the individual's MAC. For recovery, time (seconds) from discontinuation of the inhalant (with continuation of O₂) to first movement, extubation (EXT), start of incoordinated movement, head‐lift, sternal recumbency (SR), crawl, stand/walk with incoordination, and jump without incoordination were recorded. Esophageal normothermia was maintained. Data were analyzed by paired t‐test (induction) or One‐way Repeated Measures anova followed, when appropriate, by Tukey's test (recovery). p < 0.05 was regarded as significant. For induction, IM was not significantly different between ISO and SEVO (118 ± 28 seconds vs. 104 ± 28 seconds). All other induction times were significantly shorter with SEVO vs. ISO, e.g. RM (181 ± 31 seconds vs. 213 ± 31 seconds), PD (426 ± 68 seconds vs. 504 ± 70 seconds), and ET (434 ± 66 seconds vs. 515 ± 69 seconds). For recovery, there were no differences between ISO and SEVO for any stage of recovery, e.g. EXT (IS 588 ± 163 seconds vs. SS 425 ± 109 seconds), SR (IS 735 ± 215 seconds vs. SS 655 ± 337 seconds), and IL (710 ± 658 seconds vs. SL 807 ± 465 seconds). We concluded that quantitative recovery characteristics did not depend on whether cats are anesthetized with equipotent amounts of SEVO or ISO, but some induction end‐points were reached more quickly with SEVO.     

Pharmacokinetics and bone tissue concentrations of lincomycin following intravenous and intramuscular administrations to cats

Albarellos, G. A., Montoya, L., Denamiel, G. A. A., Velo, M. C., Landoni, M. F. Pharmacokinetics and bone tissue concentrations of lincomycin following intravenous and intramuscular administrations to cats. J. vet. Pharmacol. Therap.  35 , 534–540. The pharmacokinetic properties and bone concentrations of lincomycin in cats after single intravenous and intramuscular administrations at a dosage rate of 10 mg/kg were investigated. Lincomycin minimum inhibitory concentration (MIC) for some gram‐positive strains isolated from clinical cases was determined. Serum lincomycin disposition was best‐fitted to a bicompartmental and a monocompartmental open models with first‐order elimination after intravenous and intramuscular dosing, respectively. After intravenous administration, distribution was rapid (T_1/2(d) = 0.22 ± 0.09 h) and wide as reflected by the volume of distribution (V_(d(ss))) of 1.24 ± 0.08 L/kg. Plasma clearance was 0.28 ± 0.09 L/h·kg and elimination half‐life (T_1/2) 3.56 ± 0.62 h. Peak serum concentration (C_max), T_max, and bioavailability for the intramuscular administration were 7.97 ± 2.31 μg/mL, 0.12 ± 0.05 h, and 82.55 ± 23.64%, respectively. Thirty to 45 min after intravenous administration, lincomycin bone concentrations were 9.31 ± 1.75 μg/mL. At the same time after intramuscular administration, bone concentrations were 3.53 ± 0.28 μg/mL. The corresponding bone/serum ratios were 0.77 ± 0.04 (intravenous) and 0.69 ± 0.18 (intramuscular). Lincomycin MIC for Staphylococcus spp. ranged from 0.25 to 16 μg/mL and for Streptococcus spp. from 0.25 to 8 μg/mL.     

Pharmacokinetics of amantadine in cats

Siao, K. T., Pypendop, B. H., Stanley, S. D., Ilkiw, J. E. Pharmacokinetics of amantadine in cats. J. vet. Pharmacol. Therap. 34 , 599–604. This study reports the pharmacokinetics of amantadine in cats, after both i.v. and oral administration. Six healthy adult domestic shorthair female cats were used. Amantadine HCl (5 mg/kg, equivalent to 4 mg/kg amantadine base) was administered either intravenously or orally in a crossover randomized design. Blood samples were collected immediately prior to amantadine administration, and at various times up to 1440 min following intravenous, or up to 2880 min following oral administration. Plasma amantadine concentrations were determined by liquid chromatography–mass spectrometry, and plasma amantadine concentration–time data were fitted to compartmental models. A two‐compartment model with elimination from the central compartment best described the disposition of amantadine administered intravenously in cats, and a one‐compartment model best described the disposition of oral amantadine in cats. After i.v. administration, the apparent volume of distribution of the central compartment and apparent volume of distribution at steady‐state [mean ± SEM (range)], and the clearance and terminal half‐life [harmonic mean ± jackknife pseudo‐SD (range)] were 1.5 ± 0.3 (0.7–2.5) L/kg, 4.3 ± 0.2 (3.7–5.0) L/kg, 8.2 ± 2.1 (5.9–11.4) mL·min/kg, and 348 ± 49 (307–465) min, respectively. Systemic availability [mean ± SEM (range)] and terminal half‐life after oral administration [harmonic mean ± jackknife pseudo‐SD (range)] were 130 ± 11 (86–160)% and 324 ± 41 (277–381) min, respectively.     

Clinical evaluation of Alfaxan-CD® as an intravenous anaesthetic in young cats

Objective   To describe and evaluate the use of Alfaxan-CD ® as an intravenous anaesthetic in young cats.
Design   Thirty-five Domestic Short-hair cats aged from 3 to 12 months were admitted into the University Veterinary Teaching Hospital-Sydney for elective surgery. Anaesthesia was induced with Alfaxan-CD® and maintained with isoflurane: 22 cats received no premedication and 13 cats received acepromazine (0.03 mg/kg) and butorphanol (0.3 mg/kg) subcutaneously 30 min prior to induction.
Qualitative and quantitative data for induction and recovery were recorded. Physiological parameters were recorded at 0, 2 and 5 min post induction, and every 5 min thereafter until the end of the procedure.
Results   Intravenous injection of Alfaxan-CD® resulted in rapid induction of anaesthesia with a mean time to intubation of 122 s. The mean dose of Alfaxan-CD® used was 4.2 mg/kg in unpremedicated cats and 2.7 mg/kg in premedicated cats. All cats maintained a heart rate above 95 beats/min. No cat developed hypoxaemia. Hypercapnoea was detected in 4 cats and hypotension was observed in 18 cats. Time to extubation ranged from 1 to 9 min. The mean time to sternal recumbency for premedicated cats was 11 min; 77% of premedicated cats and 23% of unpremedicated cats had a recovery score of 1 or 2.
Conclusion   Alfaxan-CD® is an effective anaesthetic agent in young healthy cats, providing a smooth induction and rapid recovery. Cats that were premedicated with acepromazine and butorphanol prior to induction with Alfaxan-CD® had better recovery scores than those that were not premedicated.     

Evaluation of Propofol as a General Anesthetic for Horses

This study provides baseline information on the potential use of propofol as a general anesthetic for horses. Using a Latin square design, propofol (2, 4, and 8 mg/kg) was administered intravenously on three separate occasions to six mature horses. Information about anesthetic induction, duration, and recovery was recorded along with results of rectal temperature, heart rate, respiratory rate, pHa, Paco₂ and Pao₂. Statistical analysis included a mixed model analysis of variance, a general linear model analysis and least square means test for post hoc comparisons. A P <.05 was considered significant. The quality of induction of anesthesia varied from poor to good. Two horses were not recumbent following the lowest dose of propofol. Brief paddling limb movements occurred occasionally and unpredictably after recumbency induced by all three doses. During recovery, horses were uniformly calm and coordinated in their moves to stand. Duration of recumbency (minutes) was dose related; 15.05 ± 1.58 (±±SD) following 2 mg/kg, 31.06 ± 5.56 following 4 mg/kg, and 47.85 ± 13.63 following 8 mg/kg. During recumbency at all doses, heart rate significantly increased from a predrug value of 40 ± 6 beats per minute. Substantial respiratory depression, characterized by a significant decrease in respiratory rate (from 11.7 ± 2.9 to 3.7 ± 1.6 breaths per minute) and increased Paco₂ (from 44.5 ± 2.5 to 52.7 ± 8.0 mm Hg) was seen only after 8 mg/kg. A significant decrease in Pao₂ was observed throughout the recumbency induced by 8 mg/kg, and also at 3 and 5 minutes following induction of anesthesia with 4 mg/ kg propofol. At 5 minutes after injection, Pao₂ was 87.4 ± 13.8 and 58.1 ± 17.0 mm Hg after 4 and 8 mg/kg, respectively. The results of this study do not favor the routine use of propofol as a sole anesthetic in otherwise unmedicated horses.