Midazolam is a benzodiazepine medication commonly used in equine veterinary medicine for its sedative, anxiolytic, and muscle relaxant properties. It acts on the central nervous system by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA), leading to sedation and relaxation. In horses, midazolam is often used in combination with other drugs to facilitate procedures that require the animal to remain calm and still. The pharmacokinetics, dosage, and effects of midazolam in horses are subjects of ongoing research, as is its interaction with other medications. This page compiles peer-reviewed research studies and scholarly articles that explore the administration, effects, and safety of midazolam in equine practice.
Ruíz-López P, Cuypers C, Schauvliege S.This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg...
Parra Martínez C, Rico Pérez B, Kaartinen J.To evaluate the agreement between noninvasive arterial blood pressure (NIBP) measured from the tongue and thoracic limb with invasive blood pressure (IBP), and to compare NIBP measured from the tongue and thoracic limb in anaesthetized horses. Methods: Prospective clinical study. Methods: A group of eight client-owned healthy horses anaesthetized for scheduled procedures, American Society of Anesthesiologists classification I-II, weighing (mean ± standard deviation) 498 ± 91 kg and aged 7.8 ± 6.75 years. Methods: Animals were premedicated with intravenous (IV) romifidine (0.04-0.08 mg kg-1)...
Bukoski A, Hodgson D, Downs J, LeBert C, Thombs L, Bailey J.To compare the cardiopulmonary effects of apneustic anesthesia ventilation (AAV) and conventional mechanical ventilation (CMV) in dorsally recumbent anesthetized horses. Methods: Randomized, crossover design. Methods: A total of 10 healthy adult horses from a university-owned herd. Methods: Following xylazine, midazolam and ketamine administration, horses were orotracheally intubated and positioned in dorsal recumbency. Anesthesia was maintained with isoflurane in oxygen [inspired oxygen fraction (FiO) = 0.3 initially, with subsequent titration to maintain PaO ≥ 85 mmHg (11.3 kPa)]. Horses ...
Midon M, Yamada DI, Zangirolami Filho D, Natalini CC, Escobar A, Clark-Price SC.This randomized double-blinded study evaluated the recovery from isoflurane anesthesia in horses receiving doxapram and xylazine. 6 horses were anesthetized 4 times (minimum of 2-week washout period). Anesthesia was performed with xylazine (0.6 mg/kg), ketamine (2.2 mg/kg), midazolam (0.1 mg/kg), and maintained with isoflurane for 90 minutes. At recovery, horses received one of the following randomized treatments: RX: xylazine (0.2 mg/kg), RXD1: xylazine (0.2 mg/kg) and doxapram (0.1 mg/kg), RXD2: xylazine (0.2 mg/kg) and doxapram (0.2 mg/kg), or RS: saline. Recoveries were rope-assisted and e...
Kerr CL, Keating SCJ, Arroyo LG, Viel L.Neonatal foals may require prolonged sedation to permit ventilatory support in the first few days of life. The objective of this study was to evaluate and compare the cardiopulmonary effects and clinical recovery characteristics of 2 sedative/analgesia protocols in healthy foals receiving assisted ventilation. Foals were randomized to receive dexmedetomidine, butorphanol, and propofol (DBP) or midazolam, butorphanol, and propofol (MBP) during a 24-hour period. Infusion rates of dexmedetomidine, midazolam, and propofol were adjusted and propofol boluses administered according to set protocols t...
Cunneen A, Pratt S, Perkins N, McEwen M, Truchetti G, Rainger J, Farry T, Kidd L, Goodwin W.To evaluate the use of ketamine-medetomidine-midazolam total intravenous infusion as part of a balanced anaesthetic technique for surgical castration in horses. Five healthy Standardbred cross colts were premedicated with IV acepromazine (0.01-0.02 mg/kg), medetomidine (7 µg/kg) and methadone (0.1 mg/kg) and anaesthesia induced with IV ketamine (2.2 mg/kg) and midazolam (0.06 mg/kg). Horses were anaesthetised for 40 min with an IV infusion of ketamine (3 mg/kg/h), medetomidine (5 µg/kg/h) and midazolam (0.1 mg/kg/h) while routine surgical castration was performed. Cardiorespiratory variables...
Smith MC, Bass L, Damone J, Mama K, Rao S.The ideal field anaesthetic protocol for castration will offer an adequate duration and depth of anaesthesia using a single injection without compromising safety or recovery quality. Objective: The objective of this study was to compare intravenous (IV) xylazine and detomidine as sedatives in combination with midazolam and ketamine for induction of anaesthesia in horses undergoing field castration. Methods: Randomised, blinded, clinical study. Methods: Fifty-seven male Quarter Horses were randomly assigned to receive xylazine (group X) (1.1 mg/kg bwt) or detomidine (group D) (0.03 mg/kg bwt)...
Carregaro AB, Ueda GI, Censoni JB, Bisetto SP, Alonso BB, Reginato GM.The aim of this study was to compare the effects of methadone combined with detomidine or acepromazine on the quality of sedation and its influence over dissociative anesthesia in healthy horses. In a crossover design, seven horses were administered with 0.1 mg/kg methadone and 0.02 mg/kg detomidine intravenously (group MD) or 0.1 mg/kg methadone and 0.05 mg/kg acepromazine intravenously (group MA). Subsequently, anesthesia was induced with a combination of 2.2 mg/kg ketamine and 0.1 mg/kg midazolam intravenously. Descriptive scales and footages were used to evaluate the quality of sedat...
Wakuno A, Aoki M, Kushiro A, Mae N, Maeda T, Yamazaki Y, Minamijima Y, Nagata SI, Ohta M.To investigate the clinical pharmacokinetics and pharmacodynamics of intravenous alfaxalone in young Thoroughbred horses, seven Thoroughbred horses were randomly anaesthetised twice with either 1 or 2 mg/kg of intravenous alfaxalone after premedication with medetomidine (6 µg/kg intravenous) and midazolam (20 µg/kg intravenous). Blood samples were collected at predetermined time points up to two hours after administration. Plasma alfaxalone concentrations were quantified by a liquid chromatography tandem-mass spectrometry method and analysed by non-compartmental pharmacokinetic analy...
Pratt S, Cunneen A, Perkins N, Farry T, Kidd L, McEwen M, Rainger J, Truchetti G, Goodwin W.There is no information directly comparing midazolam with guaifenesin when used in combination with an alpha-2 agonist and ketamine to maintain anaesthesia via i.v. infusion in horses. Objective: To compare ketamine-medetomidine-guaifenesin with ketamine-medetomidine-midazolam for total intravenous anaesthesia (TIVA) in young horses anaesthetised for computerised tomography. Methods: Prospective, randomised, blinded, crossover trial. Methods: Fourteen weanlings received medetomidine 7 μg/kg bwt i.v. and anaesthesia was induced with ketamine 2.2 mg/kg bwt i.v. On two separate occasions hors...
Sage AM, Keating SC, Lascola KM, Schaeffer DJ, Clark-Price SC.To evaluate cardiopulmonary and recovery characteristics of horses administered total intravenous anesthesia (TIVA) with xylazine and ketamine combined with midazolam or propofol. Methods: Randomized crossover study. Methods: A group of eight adult horses, aged 7-22 years, weighing 493-740 kg. Methods: Horses were administered xylazine (1 mg kg) intravenously (IV), and anesthesia was induced with ketamine (2.2 mg kg) IV. Anesthesia was maintained for 45 minutes via IV infusion of xylazine (0.016 mg kg minute) and ketamine (0.03 mg kg minute) combined with midazolam at 0.002 mg kg minute (MKX),...
Jarrett MA, Bailey KM, Messenger KM, Prange T, Gaines B, Posner LP.OBJECTIVE To evaluate quality of recovery from general anesthesia in horses after induction with propofol and ketamine versus midazolam and ketamine. DESIGN Prospective randomized crossover study. ANIMALS 6 healthy adult horses. PROCEDURES Horses were premedicated with xylazine (1.0 mg/kg [0.45 mg/lb], IV), and general anesthesia was induced with midazolam (0.1 mg/kg [0.045 mg/lb], IV) or propofol (0.5 mg/kg [0.23 mg/lb], IV), followed by ketamine (3.0 mg/kg [1.36 mg/lb], IV). Horses were endotracheally intubated, and anesthesia was maintained with isoflurane. After 60 minutes, horses were giv...
Aarnes TK, Lerche P, Bednarski RM, Hubbell JAE.This study evaluated use of midazolam, ketamine, and xylazine (MKX) for total intravenous (IV) anesthesia (TIVA) in horses. Medical records of 46 horses undergoing a clinical procedure using MKX for TIVA were reviewed. Age, breed, procedure, heart rate (HR), respiratory rate (RR), pre-anesthetic drugs, induction drugs, and total volume of MKX were recorded. Duration of anesthesia, time to standing, number of attempts to stand, and recovery score were also recorded. All horses were premedicated with an alpha-2 adrenoceptor agonist and anesthesia was induced with ketamine and midazolam. Duration...
Müller TM, Hopster K, Bienert-Zeit A, Rohn K, Kästner SBR.Standing surgery, especially dental procedures, are commonly performed in horses. This leads to an increasing demand for reliable sedation protocols. Therefore, it was the purpose of this study to investigate the influence of butorphanol, midazolam or ketamine on romifidine based sedation in horses during cheek tooth removal. Methods: Forty horses presented for tooth extraction were divided in four groups using matched pair randomization. Group R was sedated with romifidine (bolus 0.03 mg/kg, followed by a constant rate infusion (CRI) 0.05 mg/kg/h) and group RB with romifidine (same dose) an...
Hopster K, Wittenberg-Voges L, Geburek F, Hopster-Iversen C, Kästner SBR.Aim of this prospective experimental study was to assess effects of systemic hypoxemia and hypovolemia on global and gastrointestinal oxygenation and perfusion in anesthetized horses. Therefore, we anesthetized twelve systemically healthy warmblood horses using either xylazine or dexmedetomidine for premedication and midazolam and ketamine for induction. Anesthesia was maintained using isoflurane in oxygen with either xylazine or dexmedetomidine and horses were ventilated to normocapnia. During part A arterial oxygen saturation (SaO) was reduced by reducing inspiratory oxygen fraction in steps...
Allison A, Robinson R, Jolliffe C, Taylor PM.There are limited investigations comparing ketamine to a ketamine-midazolam co-induction. Objective: To compare quality and safety of general anaesthesia induced using ketamine alone with anaesthesia co-induced using ketamine and midazolam. Methods: Randomised, double blinded, placebo controlled trial. Methods: After i.v. detomidine (20 μg/kg) thirty-eight ponies undergoing field castration received either 0.06 mg/kg (0.6 mL/50 kg) midazolam (group M) or 0.6 mL/50 kg placebo (group P) with 2.2 mg/kg ketamine i.v. for anaesthetic induction. Quality of anaesthetic induction, endotracheal intuba...
Wakuno A, Maeda T, Kodaira K, Kikuchi T, Ohta M.A three-year old Thoroughbred racehorse was anesthetized with sevoflurane and oxygen inhalation anesthesia combined with constant rate infusion (CRI) of alfaxalone-medetomidine for internal fixation of a third metacarpal bone fracture. After premedication with intravenous (IV) injections of medetomidine (6.0 µg/kg IV), butorphanol (25 µg/kg IV), and midazolam (20 µg/kg IV), anesthesia was induced with 5% guaifenesin (500 ml/head IV) followed immediately by alfaxalone (1.0 mg/kg IV). Anesthesia was maintained with sevoflurane and CRIs of alfaxalone (1.0 mg/kg/hr) and medetomidine (3.0 µg/kg...
Aleman M, Davis E, Knych H, Guedes A, Smith F, Madigan JE.Intrathecal lidocaine hydrochloride under general anesthesia has been used as an alternative method of euthanasia in equids. Carnivore, scavenger, and even human consumption of horse meat from carcasses have been anecdotally reported in rural areas after this method of euthanasia. The presence of drug residues in horse meat has not been investigated. Objective: To investigate if drug residues are found in horse tissues and determine their concentrations. Methods: Of 11 horses requiring euthanasia for medical reasons. Methods: Prospective descriptive study. Horses were anesthetized with total I...
Wakuno A, Aoki M, Kushiro A, Mae N, Kodaira K, Maeda T, Yamazaki Y, Ohta M.There is limited information on clinical use of the new injectable anaesthetic agent alfaxalone in Thoroughbred horses. Objective: To compare anaesthetic induction and recovery characteristics and cardiopulmonary responses between alfaxalone, ketamine and thiopental in Thoroughbred horses premedicated with medetomidine and midazolam. Methods: Randomised blinded experimental cross-over study. Methods: Six Thoroughbred horses were anaesthetised 3 times with alfaxalone 1 mg/kg bwt, ketamine 2.5 mg/kg bwt or thiopental 4 mg/kg bwt after premedication with medetomidine 6 μg/kg bwt and midazola...
Risberg ÅI, Ranheim B, Krontveit RI, Lervik A, Haga HA.To compare cardiac index and oxygen extraction at equivalent depths of anaesthesia between isoflurane-anaesthetized horses and horses anesthetized with isoflurane and dexmedetomidine CRI. Methods: Sequential, blinded, randomized, balanced, crossover study. Methods: Eight horses weighing a mean ± standard deviation of 478 ± 58 kg. Methods: Horses were premedicated with 0.03 mg kg(-1) acepromazine intramuscularly (IM) and 8 μg kg(-1) dexmedetomidine intravenously (IV). Anaesthesia was induced with 2.5 mg kg(-1) ketamine and 0.1 mg kg(-1) midazolam IV and maintained with isofluran...
Aleman M, Davis E, Williams DC, Madigan JE, Smith F, Guedes A.An intravenous (IV) overdose of pentobarbital sodium is the most commonly used method of euthanasia in veterinary medicine. However, this compound is not available in many countries or rural areas resulting in usage of alternative methods such as intrathecal lidocaine administration after IV anesthesia. Its safety and efficacy as a method of euthanasia have not been investigated in the horse. Objective: To investigate changes in mean arterial blood pressure and electrical activity of the cerebral cortex, brainstem, and heart during intrathecal administration of lidocaine. Our hypothesis was th...
Hopster K, Hopster-Iversen C, Geburek F, Rohn K, Kästner SB.The aim of this study was to assess the effect of duration of anaesthesia and concentration of isoflurane on global perfusion as well as intestinal microperfusion and oxygenation. Nine Warmblood horses were premedicated with xylazine; anaesthesia was induced with midazolam and ketamine, and maintained with isoflurane. Horses were ventilated to normocapnia. During 7 h of anaesthesia, mean arterial blood pressures (MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration (ETIso) and cardiac output using lithium dilution were measured; cardiac in...
Pakkanen SA, Raekallio MR, Mykkänen AK, Salla KM, de Vries A, Vuorilehto L, Scheinin M, Vainio OM.To investigate MK-467 as part of premedication in horses anaesthetized with isoflurane. Methods: Experimental, crossover study with a 14 day wash-out period. Methods: Seven healthy horses. Methods: The horses received either detomidine (20 μg kg(-1) IV) and butorphanol (20 μg kg(-1) IV) alone (DET) or with MK-467 (200 μg kg(-1) IV; DET + MK) as premedication. Anaesthesia was induced with ketamine (2.2 mg kg(-1) ) and midazolam (0.06 mg kg(-1) ) IV and maintained with isoflurane. Heart rate (HR), mean arterial pressure (MAP), end-tidal isoflurane concentration, end-tidal carbon ...
de Vries A, Thomson S, Taylor PM.To compare intravenous (IV) midazolam and diazepam administered with ketamine for induction of anaesthesia in ponies, already sedated with detomidine, undergoing field castration. Methods: Prospective, randomised, 'blinded', clinical study. Methods: Twenty Welsh pony yearlings. Methods: After IV injection of detomidine (20 μg kg(-1) ) and phenylbutazone (4.4 mg kg(-1) ) ponies were allocated to receive either IV midazolam (group M) or diazepam (group D) (both 0.06 mg kg(-1) ) with ketamine (2.2 mg kg(-1) ) for induction of anaesthesia. Using simple descriptive scales, quality of sedat...
Steblaj B, Schauvliege S, Pavlidou K, Gasthuys F, Savvas I, Duchateau L, Kowalczyk L, Moens Y.To compare pulmonary function and gas exchange in ponies during maintenance of anaesthesia with isoflurane or by a total intravenous anaesthesia (TIVA) technique. Methods: Experimental, cross-over study. Methods: Six healthy ponies weighing mean 286 (range 233-388) ± SD 61 kg, age 13 (9-16) ± 3 years. Methods: The ponies were anaesthetized twice, a minimum of two weeks apart. Following sedation with romifidine [80 μg kg(-1) intravenously (IV)], anaesthesia was induced IV with midazolam (0.06 mg kg(-1)) and ketamine (2.5 mg kg(-1), then maintained either with inhaled isoflurane (Fe'Iso = 1.1...
Hopster K, Ambrisko TD, Stahl J, Schramel JP, Kästner SB.Previous studies showed an influence of xylazine on the LiDCO sensor in vitro and in standing horses, but did not prove that this interaction caused error in LiDCO measurements. Therefore, agreement of cardiac output (CO) measurements by LiDCO and bolus-thermodilution (BTD) was determined in horses receiving xylazine infusions. Methods: Prospective, experimental study. Methods: Eight Warmblood horses. Methods: All horses were premedicated with xylazine. Anaesthesia was induced with midazolam and ketamine and was maintained with isoflurane in oxygen. During six hours of anaesthesia CO measureme...
Hopster K, Müller C, Hopster-Iversen C, Stahl J, Rohn K, Kästner S.To compare cardiovascular effects and recovery quality and duration of total intravenous anaesthesia (TIVA) with xylazine-ketamine-midazolam or dexmedetomidine-ketamine-midazolam. Methods: Prospective, randomized experimental cross-over trial. Methods: Eight adult warmblood horses. Methods: After sedation with acepromazine and either xylazine [0.5 mg kg(-1) , intravenously (IV)] or dexmedetomidine (3.5 μg kg(-1) IV) anaesthesia was induced with ketamine and midazolam and maintained with a constant rate infusion (CRI) of xylazine (1 mg kg(-1) hour(-1) ) [XKM] or dexmedetomidine (7 μg...
Ambrisko TD, Kabes R, Moens Y.In a previous study, the authors found a large bias (50%) for lithium (LiDCO) compared with thermodilution cardiac output measurement methods in ponies receiving i.v. infusions of xylazine, ketamine, and midazolam. This prompted the authors to examine the effect of drugs on the LiDCO sensor. Methods: Drugs and lithium were dissolved in 0.9% saline to produce the following solutions: saline, saline-lithium, saline-drug, and saline-drug-lithium. The drug concentrations were overlapping the range of clinical interest as estimated from the published literature. These 38°C solutions were pumped th...
Hubbell JA, Aarnes TK, Lerche P, Bednarski RM.To evaluate the use of midazolam, ketamine, and xylazine for total IV anesthesia (TIVA) in horses. Methods: 6 healthy Thoroughbred mares. Methods: Horses were sedated with xylazine (1.0 mg/kg, IV). Anesthesia was induced with midazolam (0.1 mg/kg, IV) followed by ketamine (2.2 mg/kg, IV) and was maintained with an IV infusion of midazolam (0.002 mg/kg/min), ketamine (0.03 mg/kg/min), and xylazine (0.016 mg/kg/min). Horses underwent surgical manipulation and injection of the palmar digital nerves; duration of the infusion was 60 minutes. Additional ketamine (0.2 to 0.4 mg/kg, IV) was administer...
Dzikiti TB, Hellebrekers LJ, van Dijk P.Physiological parameters, metabolic parameters and stress-related hormones are evaluated in horses anaesthetized with isoflurane in oxygen combined with lidocaine intravenously. Two groups of horses anaesthetized with isoflurane (six horses in each group) were studied: a lidocaine group (IL), which received intravenous lidocaine and a control group (C), which received intravenous saline. Horses in both groups were premedicated with detomidine (i.v.), and anaesthesia was induced with midazolam-ketamine (i.v.). The lidocaine group received intravenous lidocaine as a loading dose of 2.5 mg kg(-1)...
Haga HA, Lykkjen S, Revold T, Ranheim B.To evaluate the effect of intratesticular administration of lidocaine on cardiovascular responses and cremaster muscle tension during castration of isoflurane-anesthetized stallions. Methods: 28 healthy stallions (mean +/- SD age, 4.2 +/- 2.8 years) with no testicular abnormalities that were scheduled for castration. Methods: Each horse was given acepromazine (20 microg/kg, IM), romifidine (50 microg/kg, IV), and butorphanol (20 microg/kg, IV). Anesthesia was induced with ketamine (2.5 mg/kg, IV) and midazolam (50 microg/kg, IV) and maintained with isoflurane (1.7% end-tidal concentration). Af...
Müller TM, Hopster K, Bienert-Zeit A, Rohn K, Kästner SBR.Standing surgery, especially dental procedures, are commonly performed in horses. This leads to an increasing demand for reliable sedation protocols. Therefore, it was the purpose of this study to investigate the influence of butorphanol, midazolam or ketamine on romifidine based sedation in horses during cheek tooth removal. Methods: Forty horses presented for tooth extraction were divided in four groups using matched pair randomization. Group R was sedated with romifidine (bolus 0.03 mg/kg, followed by a constant rate infusion (CRI) 0.05 mg/kg/h) and group RB with romifidine (same dose) an...
Hopster K, Müller C, Hopster-Iversen C, Stahl J, Rohn K, Kästner S.To compare cardiovascular effects and recovery quality and duration of total intravenous anaesthesia (TIVA) with xylazine-ketamine-midazolam or dexmedetomidine-ketamine-midazolam. Methods: Prospective, randomized experimental cross-over trial. Methods: Eight adult warmblood horses. Methods: After sedation with acepromazine and either xylazine [0.5 mg kg(-1) , intravenously (IV)] or dexmedetomidine (3.5 μg kg(-1) IV) anaesthesia was induced with ketamine and midazolam and maintained with a constant rate infusion (CRI) of xylazine (1 mg kg(-1) hour(-1) ) [XKM] or dexmedetomidine (7 μg...
Aleman M, Davis E, Williams DC, Madigan JE, Smith F, Guedes A.An intravenous (IV) overdose of pentobarbital sodium is the most commonly used method of euthanasia in veterinary medicine. However, this compound is not available in many countries or rural areas resulting in usage of alternative methods such as intrathecal lidocaine administration after IV anesthesia. Its safety and efficacy as a method of euthanasia have not been investigated in the horse. Objective: To investigate changes in mean arterial blood pressure and electrical activity of the cerebral cortex, brainstem, and heart during intrathecal administration of lidocaine. Our hypothesis was th...
Allison A, Robinson R, Jolliffe C, Taylor PM.There are limited investigations comparing ketamine to a ketamine-midazolam co-induction. Objective: To compare quality and safety of general anaesthesia induced using ketamine alone with anaesthesia co-induced using ketamine and midazolam. Methods: Randomised, double blinded, placebo controlled trial. Methods: After i.v. detomidine (20 μg/kg) thirty-eight ponies undergoing field castration received either 0.06 mg/kg (0.6 mL/50 kg) midazolam (group M) or 0.6 mL/50 kg placebo (group P) with 2.2 mg/kg ketamine i.v. for anaesthetic induction. Quality of anaesthetic induction, endotracheal intuba...
Hopster K, Hopster-Iversen C, Geburek F, Rohn K, Kästner SB.The aim of this study was to assess the effect of duration of anaesthesia and concentration of isoflurane on global perfusion as well as intestinal microperfusion and oxygenation. Nine Warmblood horses were premedicated with xylazine; anaesthesia was induced with midazolam and ketamine, and maintained with isoflurane. Horses were ventilated to normocapnia. During 7 h of anaesthesia, mean arterial blood pressures (MAP), heart rate, central venous pressure, pulmonary artery pressure, expiratory isoflurane concentration (ETIso) and cardiac output using lithium dilution were measured; cardiac in...
Risberg ÅI, Ranheim B, Krontveit RI, Lervik A, Haga HA.To compare cardiac index and oxygen extraction at equivalent depths of anaesthesia between isoflurane-anaesthetized horses and horses anesthetized with isoflurane and dexmedetomidine CRI. Methods: Sequential, blinded, randomized, balanced, crossover study. Methods: Eight horses weighing a mean ± standard deviation of 478 ± 58 kg. Methods: Horses were premedicated with 0.03 mg kg(-1) acepromazine intramuscularly (IM) and 8 μg kg(-1) dexmedetomidine intravenously (IV). Anaesthesia was induced with 2.5 mg kg(-1) ketamine and 0.1 mg kg(-1) midazolam IV and maintained with isofluran...
Ambrisko TD, Kabes R, Moens Y.In a previous study, the authors found a large bias (50%) for lithium (LiDCO) compared with thermodilution cardiac output measurement methods in ponies receiving i.v. infusions of xylazine, ketamine, and midazolam. This prompted the authors to examine the effect of drugs on the LiDCO sensor. Methods: Drugs and lithium were dissolved in 0.9% saline to produce the following solutions: saline, saline-lithium, saline-drug, and saline-drug-lithium. The drug concentrations were overlapping the range of clinical interest as estimated from the published literature. These 38°C solutions were pumped th...
Auer U, Moens Y.The production of a central eye to ease surgical access for intraocular surgery is generally dependent on the depth of anesthesia. The aim of this study was to evaluate the eyeball position under muscle relaxation with rocuronium during general anesthesia. Methods: Twenty horses, body weight 480 ± 62 kg; age 12.6 ± 6.2 years (mean ± SD) were anesthetised for various ophthalmic surgeries. Horses were premedicated with acepromazine, xylazine, and butorphanol intravenously and anesthesia induced with ketamine and diazepam. Anesthesia was maintained with isoflurane in 100% oxyge...
Sage AM, Keating SC, Lascola KM, Schaeffer DJ, Clark-Price SC.To evaluate cardiopulmonary and recovery characteristics of horses administered total intravenous anesthesia (TIVA) with xylazine and ketamine combined with midazolam or propofol. Methods: Randomized crossover study. Methods: A group of eight adult horses, aged 7-22 years, weighing 493-740 kg. Methods: Horses were administered xylazine (1 mg kg) intravenously (IV), and anesthesia was induced with ketamine (2.2 mg kg) IV. Anesthesia was maintained for 45 minutes via IV infusion of xylazine (0.016 mg kg minute) and ketamine (0.03 mg kg minute) combined with midazolam at 0.002 mg kg minute (MKX),...
Hubbell JA, Aarnes TK, Lerche P, Bednarski RM.To evaluate the use of midazolam, ketamine, and xylazine for total IV anesthesia (TIVA) in horses. Methods: 6 healthy Thoroughbred mares. Methods: Horses were sedated with xylazine (1.0 mg/kg, IV). Anesthesia was induced with midazolam (0.1 mg/kg, IV) followed by ketamine (2.2 mg/kg, IV) and was maintained with an IV infusion of midazolam (0.002 mg/kg/min), ketamine (0.03 mg/kg/min), and xylazine (0.016 mg/kg/min). Horses underwent surgical manipulation and injection of the palmar digital nerves; duration of the infusion was 60 minutes. Additional ketamine (0.2 to 0.4 mg/kg, IV) was administer...
Hopster K, Ambrisko TD, Stahl J, Schramel JP, Kästner SB.Previous studies showed an influence of xylazine on the LiDCO sensor in vitro and in standing horses, but did not prove that this interaction caused error in LiDCO measurements. Therefore, agreement of cardiac output (CO) measurements by LiDCO and bolus-thermodilution (BTD) was determined in horses receiving xylazine infusions. Methods: Prospective, experimental study. Methods: Eight Warmblood horses. Methods: All horses were premedicated with xylazine. Anaesthesia was induced with midazolam and ketamine and was maintained with isoflurane in oxygen. During six hours of anaesthesia CO measureme...
Pakkanen SA, Raekallio MR, Mykkänen AK, Salla KM, de Vries A, Vuorilehto L, Scheinin M, Vainio OM.To investigate MK-467 as part of premedication in horses anaesthetized with isoflurane. Methods: Experimental, crossover study with a 14 day wash-out period. Methods: Seven healthy horses. Methods: The horses received either detomidine (20 μg kg(-1) IV) and butorphanol (20 μg kg(-1) IV) alone (DET) or with MK-467 (200 μg kg(-1) IV; DET + MK) as premedication. Anaesthesia was induced with ketamine (2.2 mg kg(-1) ) and midazolam (0.06 mg kg(-1) ) IV and maintained with isoflurane. Heart rate (HR), mean arterial pressure (MAP), end-tidal isoflurane concentration, end-tidal carbon ...
Wakuno A, Aoki M, Kushiro A, Mae N, Kodaira K, Maeda T, Yamazaki Y, Ohta M.There is limited information on clinical use of the new injectable anaesthetic agent alfaxalone in Thoroughbred horses. Objective: To compare anaesthetic induction and recovery characteristics and cardiopulmonary responses between alfaxalone, ketamine and thiopental in Thoroughbred horses premedicated with medetomidine and midazolam. Methods: Randomised blinded experimental cross-over study. Methods: Six Thoroughbred horses were anaesthetised 3 times with alfaxalone 1 mg/kg bwt, ketamine 2.5 mg/kg bwt or thiopental 4 mg/kg bwt after premedication with medetomidine 6 μg/kg bwt and midazola...
Hopster K, Wittenberg-Voges L, Geburek F, Hopster-Iversen C, Kästner SBR.Aim of this prospective experimental study was to assess effects of systemic hypoxemia and hypovolemia on global and gastrointestinal oxygenation and perfusion in anesthetized horses. Therefore, we anesthetized twelve systemically healthy warmblood horses using either xylazine or dexmedetomidine for premedication and midazolam and ketamine for induction. Anesthesia was maintained using isoflurane in oxygen with either xylazine or dexmedetomidine and horses were ventilated to normocapnia. During part A arterial oxygen saturation (SaO) was reduced by reducing inspiratory oxygen fraction in steps...
Jarrett MA, Bailey KM, Messenger KM, Prange T, Gaines B, Posner LP.OBJECTIVE To evaluate quality of recovery from general anesthesia in horses after induction with propofol and ketamine versus midazolam and ketamine. DESIGN Prospective randomized crossover study. ANIMALS 6 healthy adult horses. PROCEDURES Horses were premedicated with xylazine (1.0 mg/kg [0.45 mg/lb], IV), and general anesthesia was induced with midazolam (0.1 mg/kg [0.045 mg/lb], IV) or propofol (0.5 mg/kg [0.23 mg/lb], IV), followed by ketamine (3.0 mg/kg [1.36 mg/lb], IV). Horses were endotracheally intubated, and anesthesia was maintained with isoflurane. After 60 minutes, horses were giv...
de Vries A, Thomson S, Taylor PM.To compare intravenous (IV) midazolam and diazepam administered with ketamine for induction of anaesthesia in ponies, already sedated with detomidine, undergoing field castration. Methods: Prospective, randomised, 'blinded', clinical study. Methods: Twenty Welsh pony yearlings. Methods: After IV injection of detomidine (20 μg kg(-1) ) and phenylbutazone (4.4 mg kg(-1) ) ponies were allocated to receive either IV midazolam (group M) or diazepam (group D) (both 0.06 mg kg(-1) ) with ketamine (2.2 mg kg(-1) ) for induction of anaesthesia. Using simple descriptive scales, quality of sedat...
Carregaro AB, Ueda GI, Censoni JB, Bisetto SP, Alonso BB, Reginato GM.The aim of this study was to compare the effects of methadone combined with detomidine or acepromazine on the quality of sedation and its influence over dissociative anesthesia in healthy horses. In a crossover design, seven horses were administered with 0.1 mg/kg methadone and 0.02 mg/kg detomidine intravenously (group MD) or 0.1 mg/kg methadone and 0.05 mg/kg acepromazine intravenously (group MA). Subsequently, anesthesia was induced with a combination of 2.2 mg/kg ketamine and 0.1 mg/kg midazolam intravenously. Descriptive scales and footages were used to evaluate the quality of sedat...
Marcilla MG, Schauvliege S, Duchateau L, Gasthuys F.To evaluate the cardiopulmonary effects of two different constant rate infusions (CRI) of dexmedetomidine (1 and 1.75 microg kg(-1 )hour(-1)) in experimental ponies. Methods: Six healthy ponies (mean 306 +/- SD 71 kg, 7.0 +/- 1.6 years). Methods: Prospective, randomized, experimental study. Methods: After premedication with intravenous (IV) dexmedetomidine (3.5 microg kg(-1)), anaesthesia was induced (T0) with ketamine (2.2 mg kg(-1) IV) and midazolam (0.06 mg kg(-1) IV) and maintained with isoflurane (Fe'ISO 1.50%) in 55% oxygen for 150 minutes. Normocapnia was maintained using artificial ven...
Pratt S, Cunneen A, Perkins N, Farry T, Kidd L, McEwen M, Rainger J, Truchetti G, Goodwin W.There is no information directly comparing midazolam with guaifenesin when used in combination with an alpha-2 agonist and ketamine to maintain anaesthesia via i.v. infusion in horses. Objective: To compare ketamine-medetomidine-guaifenesin with ketamine-medetomidine-midazolam for total intravenous anaesthesia (TIVA) in young horses anaesthetised for computerised tomography. Methods: Prospective, randomised, blinded, crossover trial. Methods: Fourteen weanlings received medetomidine 7 μg/kg bwt i.v. and anaesthesia was induced with ketamine 2.2 mg/kg bwt i.v. On two separate occasions hors...
Smith MC, Bass L, Damone J, Mama K, Rao S.The ideal field anaesthetic protocol for castration will offer an adequate duration and depth of anaesthesia using a single injection without compromising safety or recovery quality. Objective: The objective of this study was to compare intravenous (IV) xylazine and detomidine as sedatives in combination with midazolam and ketamine for induction of anaesthesia in horses undergoing field castration. Methods: Randomised, blinded, clinical study. Methods: Fifty-seven male Quarter Horses were randomly assigned to receive xylazine (group X) (1.1 mg/kg bwt) or detomidine (group D) (0.03 mg/kg bwt)...
Kushiro T, Yamashita K, Umar MA, Maehara S, Wakaiki S, Abe R, Seno T, Tsuzuki K, Izumisawa Y, Muir WW.The anesthetic sparring and cardiovascular effects produced by midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.05 mg/ml (0.025 ml/kg/hr) drug infusion during sevoflurane in oxygen (MKM-OS) anesthesia was determined in healthy horses. The anesthetic sparring effects of MKM-OS were assessed in 6 healthy thoroughbred horses in which the right carotid artery was surgically relocated to a subcutaneous position. All horses were intubated and ventilated with oxygen using intermittent positive pressure ventilation (IPPV). The end-tidal concentration of sevoflurane (ET(SEV)) required to maintain s...
Gangl M, Grulke S, Detilleux J, Caudron I, Serteyn D.Forty-eight horses subjected to elective surgery were randomly assigned to three groups of 16 horses. After premedication with 0.1 mg/kg acepromazine intramuscularly and 0.6 mg/kg xylazine intravenously, anaesthesia was induced either with 2 g thiopentone in 500 ml of a 10 per cent guaifenesin solution, given intravenously at a dose of 1 ml/kg (group TG), or with 100 mg/kg guaifenesin and 2.2 mg/kg ketamine given intravenously (group KG), or with 0.06 mg/kg midazolam, and 2.2 mg/kg ketamine given intravenously (group KM). Anaesthesia was maintained with isoflurane. The mean (sd) end tidal isof...
Wakuno A, Maeda T, Kodaira K, Kikuchi T, Ohta M.A three-year old Thoroughbred racehorse was anesthetized with sevoflurane and oxygen inhalation anesthesia combined with constant rate infusion (CRI) of alfaxalone-medetomidine for internal fixation of a third metacarpal bone fracture. After premedication with intravenous (IV) injections of medetomidine (6.0 µg/kg IV), butorphanol (25 µg/kg IV), and midazolam (20 µg/kg IV), anesthesia was induced with 5% guaifenesin (500 ml/head IV) followed immediately by alfaxalone (1.0 mg/kg IV). Anesthesia was maintained with sevoflurane and CRIs of alfaxalone (1.0 mg/kg/hr) and medetomidine (3.0 µg/kg...
Aarnes TK, Lerche P, Bednarski RM, Hubbell JAE.This study evaluated use of midazolam, ketamine, and xylazine (MKX) for total intravenous (IV) anesthesia (TIVA) in horses. Medical records of 46 horses undergoing a clinical procedure using MKX for TIVA were reviewed. Age, breed, procedure, heart rate (HR), respiratory rate (RR), pre-anesthetic drugs, induction drugs, and total volume of MKX were recorded. Duration of anesthesia, time to standing, number of attempts to stand, and recovery score were also recorded. All horses were premedicated with an alpha-2 adrenoceptor agonist and anesthesia was induced with ketamine and midazolam. Duration...
Steblaj B, Schauvliege S, Pavlidou K, Gasthuys F, Savvas I, Duchateau L, Kowalczyk L, Moens Y.To compare pulmonary function and gas exchange in ponies during maintenance of anaesthesia with isoflurane or by a total intravenous anaesthesia (TIVA) technique. Methods: Experimental, cross-over study. Methods: Six healthy ponies weighing mean 286 (range 233-388) ± SD 61 kg, age 13 (9-16) ± 3 years. Methods: The ponies were anaesthetized twice, a minimum of two weeks apart. Following sedation with romifidine [80 μg kg(-1) intravenously (IV)], anaesthesia was induced IV with midazolam (0.06 mg kg(-1)) and ketamine (2.5 mg kg(-1), then maintained either with inhaled isoflurane (Fe'Iso = 1.1...
Aleman M, Davis E, Knych H, Guedes A, Smith F, Madigan JE.Intrathecal lidocaine hydrochloride under general anesthesia has been used as an alternative method of euthanasia in equids. Carnivore, scavenger, and even human consumption of horse meat from carcasses have been anecdotally reported in rural areas after this method of euthanasia. The presence of drug residues in horse meat has not been investigated. Objective: To investigate if drug residues are found in horse tissues and determine their concentrations. Methods: Of 11 horses requiring euthanasia for medical reasons. Methods: Prospective descriptive study. Horses were anesthetized with total I...
Johnson CB, Bloomfield M, Taylor PM.The electroencephalographic (EEG) effects of a rapid infusion of midazolam and sarmazenil following a bolus of midazolam were investigated in eight Welsh mountain ponies anaesthetized with 0.8% halothane in oxygen. The peak plasma concentration of midazolam was 2.13 +/- 0.34 ng/mL (mean +/- SD) occurring 5 min after the start of the infusion. Sarmazenil concentrations were not measured. The 95% spectral edge frequency of the EEG decreased by a maximum of 39.8 +/- 15.8%, 10 min after the start of the midazolam infusion. No changes were seen in median frequency of the EEG or the second different...
