Medetomidine is an alpha-2 adrenergic agonist used in veterinary medicine for its sedative, analgesic, and muscle relaxant properties in horses. It acts on the central nervous system by binding to alpha-2 adrenergic receptors, resulting in decreased release of norepinephrine and subsequent sedation. Medetomidine is employed in various clinical settings, including premedication for anesthesia, minor surgical procedures, and managing pain. The effects of medetomidine can be reversed with the administration of atipamezole, an alpha-2 adrenergic antagonist. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacodynamics, pharmacokinetics, and clinical applications of medetomidine in equine practice.
Minamijima Y, Kuroda T, Maeda Y, Narita S, Yamashita S, Yamada M.Medetomidine, an α₂-adrenergic agonist, is widely used as a sedative in horses. While its pharmacological effects are established, limited data exist on elimination of its metabolites, 3'-hydroxy medetomidine (HMD) and 3'-carboxy medetomidine (CMD), which are of regulatory interest. HMD is currently targeted in plasma and urine under International Screening Limits (ISLs) established by the International Federation of Horseracing Authorities (IFHA). In this study, seven Thoroughbreds received 6.3 μg/kg of medetomidine intravenously. Blood and urine were collected for 96 h and analyzed b...
Bardhi A, Barbarossa A, Joubert A, Gehring R, Lambertini C, Romagnoli N.Dried blood spot (DBS) sampling has emerged as a promising microsampling technique in biomedical and clinical research, offering advantages such as reduced invasiveness, minimal blood volume requirements, and enhanced analyte stability. Although well established in human medicine for neonatal screening and diagnostic applications, its potential in veterinary pharmacology remains underexplored. This study investigated the feasibility of using DBS samples to quantify anesthetic agents-ketamine and medetomidine in cats and lidocaine in horses-during routine surgical procedures at a veterinary tea...
Schiele AR, Valletti C, Ringer SK.A Trotter mare (aged 5 years 8 months) presented with severe thoracic limb lameness 2 years after screw fixation of a third carpal bone fracture. Septic arthritis of the intermediate carpal joint necessitated three anaesthetics: two arthroscopic lavages in dorsal recumbency, followed by a computed tomography-guided screw explantation with curettage of an infected, sclerotic third carpal bone in right lateral recumbency. For each anaesthetic, maintenance was with isoflurane carried in oxygen and air, and a medetomidine constant rate infusion. Twelve days after the third anaesthetic, the horse h...
Hordle T, Ranninger E, Bettschart-Wolfensberger R.A 24 year old warmblood mare (case 1) and a 12 year old Holsteiner gelding (case 2) were anaesthetized for bursoscopy and phacoemulsification, respectively. Both were premedicated with intramuscular acepromazine (30 μg kg-1). The horses were sedated with intravenous (IV) medetomidine (7-9 μg kg-1 to effect), before anaesthetic induction with ketamine-diazepam. Anaesthesia was maintained with isoflurane in a mixture of oxygen and medical air, alongside a medetomidine constant rate infusion at 3.5 μg kg-1 hour-1. In recovery, 3 and 5 μg kg-1 of medetomidine were administered IV to cases 1 an...
Medina-Bautista F, Morgaz J, Domínguez JM, Navarrete-Calvo R, Sánchez de Medina A, Quirós-Carmona S, Granados MDM.Recovery from general anaesthesia is risky in horses. Alpha-agonist administration after anaesthesia enhances the quality of recovery but may prolong this phase. Recovery time and quality were investigated after medetomidine administration at the end of general anaesthesia in a prospective, randomised, masked and clinical study. Horses underwent medetomidine-isoflurane partial intravenous anaesthesia. Medetomidine (0.5 or 1 µg/kg) IV was administered just after isoflurane was discontinued. The duration of different recovery phases and the number of attempts were recorded. A composite scale (f...
Straticò P, Guerri G, Bandera L, Celani G, Di Nunzio L, Petrizzi L, Varasano V.(1) The main goals of general anesthesia include pain management and a safe anesthetic protocol for smooth recovery. In this retrospective study, we compared two anesthetic protocols for general anesthesia with isoflurane during emergency laparotomy: sedation with xylazine and the intraoperative infusion of lidocaine (X group) versus medetomidine as a preoperative sedation and intraoperative infusion (M group). (2) The medical records of horses who underwent emergency laparotomies between 2016 and 2023 were reviewed. According to the anesthetic protocol, patients were allocated to the X or M g...
Meier M, Kazmir-Lysak K, Kälin I, Torgerson PR, Ringer SK.To investigate the effect of hypoxaemia, hypotension and hypercapnia, among others, on quality of recovery from general anaesthesia in horses. Methods: Retrospective, single-centre study. Methods: A sample of 1226 horses that underwent general anaesthesia between June 2017 and June 2021. Methods: Horses and ponies weighing > 200 kg, aged > 6 months, anaesthetized using a xylazine- or medetomidine-isoflurane balanced anaesthesia protocol and presenting a complete anaesthetic record were included. Data were extracted from the clinic record system and from the original anaesthesia records. Recove...
Bohner J, Painer J, Bakker D, Haw AJ, Rauch H, Greunz EM, Egner B, Goeritz F.Etorphine is widely used in zoological medicine for the immobilization of large herbivores. All reported immobilization protocols for kulans use etorphine as the primary immobilizing agent. However, etorphine can trigger severe side effects and is highly toxic for humans, its availability is occasionally limited for use in wildlife medicine. Therefore, two different alpha-2 agonist-based protocols for the general anesthesia of kulans were investigated and compared with the standard etorphine immobilization. In total, 21 immobilizations were performed within the scope of routine husbandry manag...
Milnes EL, Skelding AM, Larouche CB, Ferro A, Delnatte P, Dutton C, Anderson NE.To compare ketamine-butorphanol-azaperone-medetomidine (KBAM) to detomidine-etorphine-acepromazine (DEA) for field anesthesia in captive Przewalski horses (Equus przewalskii). Methods: 10 adult Przewalski horses. Methods: A prospective randomized crossover trial was conducted. Each horse was immobilized once with KBAM (200 mg ketamine, 109.2 mg butorphanol, 36.4 mg azaperone, and 43.6 mg medetomidine) and once with DEA (40 mg detomidine premedication, followed 20 minutes later by 3.9 to 4.4 mg etorphine and 16 to 18 mg acepromazine). Both protocols were administered by IM remote dart injection...
Samimi AS, Molaei MM, Azari O, Rezaei MA, Hashemian A.The present study aimed to compare the sedative and analgesic effects of caudal epidural administration of lidocaine alone or in combination with four different α-adrenergic agonists in Mediterranean miniature donkeys. A total of ten clinically healthy (five males and five females) Mediterranean miniature donkeys with an age of 5 ± 1 years, a weight of 100 ± 2 kg and a height at the withers of 0.8 ± 0.06 m (mean ± standard deviation) were used in experimental, crossover (Latin square), randomized, and blinded study. Animals were assigned to five treatment groups including lidocaine alone ...
Cowling N, Woldeyohannes S, Sole Guitart A, Goodwin W.Near infrared spectroscopy (NIRS) noninvasively measures peripheral tissue oxygen saturation (StO) and may be useful to detect early changes in StO in anaesthetized and critically ill horses. This study aimed to identify the muscle belly that provided the highest percentage of successful StO readings and the highest mean StO value. Fifty adult horses were enrolled in a prospective controlled study. StO was measured at six different muscles in each horse, for each intervention: hair overlying the muscle was clipped (post clipping: PC), clipped skin was cleaned with chlorhexidine (post-surgical ...
Kälin I, Henze IS, Ringer SK, Torgerson PR, Bettschart-Wolfensberger R.Medetomidine partial intravenous anaesthesia (PIVA) has not been compared to xylazine PIVA regarding quality of recovery. This clinical retrospective study compared recoveries following isoflurane anaesthesia balanced with medetomidine or xylazine. The following standard protocol was used: sedation with 7 µg·kg medetomidine or 1.1 mg·kg xylazine, anaesthesia induction with ketamine/diazepam, maintenance with isoflurane and 3.5 µg·kg·h medetomidine or 0.7 mg·kg·h xylazine, and sedation after anaesthesia with 2 µg·kg medetomidine or 0.3 mg·kg xylazine. Recovery was timed and, using vi...
Balko JA, Fogle C, Stuska SJ, Fogle JE, Posner LP.Butorphanol-azaperone-medetomidine (BAM™) has not been evaluated in horses. Objective: The objective of this study was to evaluate BAM™ for chemical restraint of feral horses. Methods: Retrospective and prospective descriptive studies. Methods: Data were collected retrospectively from medical records of 28 feral horses immobilised with BAM™ over a 6-year period. Prospectively, 0.0125 mL/kg bwt of BAM™ (butorphanol 27.3 mg/mL, azaperone 9.1 mg/mL and medetomidine 10.9 mg/mL) intramuscularly (im) was administered to eight stallions via dart, and once recumbent, 1.0 mg/kg bwt ketamin...
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...
Troya-Portillo L, López-Sanromán J, Villalba-Orero M, Santiago-Llorente I.Standing surgery under sedation reduces anesthetic-related mortality in horses. Medetomidine, alone and combined with morphine in a constant rate infusion (CRI), has been described for standing surgery but their cardiorespiratory, sedative and antinociceptive effects have never been compared. The addition of ketamine could improve analgesia in these procedures with minimal cardiorespiratory consequences. The objectives were to compare the cardiorespiratory effects, quality of sedation, antinociception and ataxia produced by administration of a medetomidine-based CRI with morphine, ketamine or ...
Roşu O, Melega I, Evans AL, Arnemo JM, Küker S.Feral horses are immobilized for a variety of reasons including population control via contraceptives. Although opioid combinations have been successfully used for immobilization of feral horses, there is a need for combinations using drugs that are more readily available and present less of a human health hazard. We evaluated the chemical immobilization with physiological measurements and blood gas analyses of 91 free-ranging feral horses () remotely immobilized with a combination of 30 mg medetomidine and 775 mg ketamine in a single disposable 6 ml dart. During immobilization, heart rate, re...
Ellis JS, Mama KR, Rao S, Sadler RA, Marinkovich M, Clancy MM, Howard LL, Lamberski N, Kinney ME.Przewalski's horses () are an endangered equid species. Anesthesia administered by remote delivery is often needed to provide medical care. Behavioral and physiologic parameters were prospectively compared in 14 horses (8 females and 6 males, 3-18 yr) after a single-dart or staged two-dart anesthesia induction protocol with intramuscular medetomidine (0.06 mg/kg), butorphanol (0.05 mg/kg), thiafentanil (0.02 mg/kg), and ketamine (1 mg/kg). Seven horses were randomly assigned to receive all drugs in a single dart, and the other seven to receive medetomidine and butorphanol 10 min prior to thiaf...
Wiederkehr A, Barbarossa A, Ringer SK, Jörger FB, Bryner M, Bettschart-Wolfensberger R. To assess drug plasma levels, preanesthetic sedation, cardiopulmonary effects during anesthesia and recovery in horses anesthetized with isoflurane combined with medetomidine or xylazine. Prospective blinded randomized clinical study. Sixty horses undergoing elective surgery. Thirty minutes after administration of antibiotics, flunixine meglumine or phenylbutazone and acepromazine horses received medetomidine 7 μg kg (group MED) or xylazine 1.1 mg kg (group XYL) slowly intravenously (IV) and sedation was assessed 3 min later. Anesthesia was induced with ketamine/diazepam and maintained wi...
Kim A, Sasaki N, Lee I, Seo JP.The purpose of this study was to assess the cardiorespiratory and behavioral responses to the combination of medetomidine and tramadol (M-T) or butorphanol (M-B) in standing laparoscopic ovariectomy in horses. One ovary was removed under M-T and the contralateral ovary was removed under M-B with at least 4 weeks between operations at random. Horses were sedated using intravenous medetomidine (5 µg/kg) followed by tramadol (1 mg/kg) or butorphanol (10 µg/kg) after 5 min. Sedation was maintained through the repeated injection of medetomidine (1 µg/kg) and tramadol (0.4 mg/kg) or medetomidine ...
Navarrete-Calvo R, Morgaz J, Gómez-Villamandos RJ, Quirós-Carmona S, Domínguez JM, Ruiz-López P, Granados MM.The bispectral index (BIS) has been evaluated as an indicator of central nervous system (CNS) depression in horses during general anaesthesia. The spectral entropy is another electroencephalographic device and it has not been evaluated yet in horses. Objective: To determine if spectral entropy can assess anaesthetic depth during the different phases of anaesthesia, define the value of state and response entropy during surgical plane of anaesthesia and compare them with BIS. Methods: Clinical, prospective, non-blinded observational study. Methods: Thirty-five horses ASA I or II undergoing sched...
Karakka Kal AK, Nalakath J, Kunhamu Karatt T, Perwad Z, Mathew B, Subhahar M.The detection and separation of medetomidine enantiomers from the complex biological matrices poses a great analytical challenge, especially in the field of forensic toxicology and pharmacology. Couple of researchers reported resolution of medetomidine using protein-based chiral columns, but the reported method is quiet challenging and tedious to be employed for routine analysis. This research paper reported a method that enables the enantio-separation of medetomidine by using polysaccharide cellulose chiral column. The use of chiralcel OJ-3R column was found to have the highest potential for ...
Hollis AR, Pascal M, Van Dijk J, Jolliffe C, Kaartinen J.To compare the efficacy of a medetomidine constant rate infusion (CRI) with a detomidine CRI for standing sedation in horses undergoing high dose rate brachytherapy. Methods: Randomized, controlled, crossover, blinded clinical trial. Methods: A total of 50 horses with owner consent, excluding stallions. Methods: Each horse was sedated with intravenous acepromazine (0.02 mg kg-1), followed by an α2-adrenoceptor agonist 30 minutes later and then by butorphanol (0.1 mg kg-1) 5 minutes later. A CRI of the same α2-adrenoceptor agonist was started 10 minutes after butorphanol administration and ma...
Rossi H, Raekallio M, Määttä M, Tapio H, Hanifeh M, Junnila J, Rajamäki MM, Mykkänen A.Pneumonia is one of the potential complications of general anaesthesia in horses. Anaesthesia is known to increase neutrophils in bronchoalveolar lavage fluid (BALF) of horses after lateral recumbency, but studies after dorsal recumbency are lacking. Our primary aim was to determine when lung inflammation reaches its maximum and how rapidly BALF cytology returns to baseline after anaesthesia in dorsal recumbency. A secondary aim was to investigate the possible effect of vatinoxan, a novel drug, on the BALF cytology results. Six healthy experimental horses were enrolled in this observational cr...
Tapio HA, Raekallio MR, Mykkänen AK, Al-Ramahi D, Scheinin M, Hautajärvi HJ, Männikkö S, Vainio O.A constant rate infusion (CRI) of medetomidine is used to balance equine inhalation anesthesia, but its cardiovascular side effects are a concern. This experimental crossover study aimed to evaluate the effects of vatinoxan (a peripheral α2-adrenoceptor antagonist) on cardiorespiratory and gastrointestinal function in anesthetized healthy horses. Six horses received medetomidine hydrochloride 7μg/kg IV alone (MED) or with vatinoxan hydrochloride 140μg/kg IV (MED+V). Anesthesia was induced with midazolam and ketamine and maintained with isoflurane and medetomidine CRI for 60min. Heart rate, ...
Tokushige H, Araki M, Kusano K, Arima D, Ito H, Yamazaki Y, Urayama S, Kambayashi Y, Tateno O, Ohta M.This study compares clinical characteristics between induction with thiopental/guaifenesin and propofol/ketamine in Thoroughbred racehorses anesthetized with sevoflurane and medetomidine. Clinical records of 214 horses that underwent arthroscopic surgery between 2015 and 2016 were retrospectively retrieved. Horses were premedicated with medetomidine and midazolam to sedate at the adequate level for smooth induction, and then induced with either thiopental (4.0 mg/kg) and guaifenesin (100 mg/kg) in Group TG (n=91) or propofol (1.0 mg/kg) and ketamine (1.0 mg/kg) in Group PK (n=123). Anesthesia ...
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...
Tapio H, Raekallio MR, Mykkänen A, Männikkö S, Scheinin M, Bennett RC, Vainio O.Medetomidine suppresses cardiovascular function and reduces gastrointestinal motility in horses mainly through peripheral α -adrenoceptors. Vatinoxan, a peripheral α -antagonist, has been shown experimentally to alleviate the adverse effects of some α -agonists in horses. However, vatinoxan has not been investigated during constant-rate infusion (CRI) of medetomidine in standing horses. Objective: To evaluate effects of vatinoxan on cardiovascular function, gastrointestinal motility and on sedation level during CRI of medetomidine. Methods: Experimental, randomised, blinded, cross-over stud...
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...
Tokushige H, Okano A, Arima D, Ito H, Kambayashi Y, Minamijima Y, Ohta M.The aim of the present study was to evaluate clinical efficacy of constant rate infusions (CRIs) of medetomidine-propofol combined with sevoflurane anesthesia in Thoroughbred racehorses undergoing arthroscopic surgery. Thirty horses were sedated intravenously (IV) with medetomidine (6.0 μg/kg) and midazolam (0.02 mg/kg) and induced IV with ketamine (1.0 mg/kg) and propofol (1.0 mg/kg). These horses were randomly allocated to three groups and maintained with sevoflurane and CRI of either medetomidine (3.0 μg/kg/h) (Group M; n = 10); or medetomidine (3.0 μg/kg/h) and propofol (3.0 ...
Yamashita K, Tsubakishita S, Futaok S, Ueda I, Hamaguchi H, Seno T, Katoh S, Izumisawa Y, Kotani T, Muir WW.The cardiovascular effects of medetomidine, detomidine, and xylazine in horses were studied. Fifteen horses, whose right carotid arteries had previously been surgically raised to a subcutaneous position during general anesthesia were used. Five horses each were given the following 8 treatments: an intravenous injection of 4 doses of medetomidine (3, 5, 7.5, and 10 microg/kg), 3 doses of detomidine (10, 20, and 40 microg/kg), and one dose of xylazine (1 mg/kg). Heart rate decreased, but not statistically significant. Atrio-ventricular block was observed following all treatments and prolonged wi...
England GC, Clarke KW.In recent years the usefulness of the alpha 2 adrenoceptor agonist drugs has been recognized in equine practice. Several agents have become available and are now licensed for use in a number of countries. The principle actions of all alpha 2 adrenoceptor agonists are similar, in that they produce a reduction in heart rate and alteration of heart rhythm, an initial hypertension followed by a prolonged hypotension, a decrease in the cardiac output and respiratory depression. For clinical purposes, these agents produce sedation and analgesia, they are useful for premedication and markedly potenti...
Gozalo-Marcilla M, Gasthuys F, Schauvliege S.To review the literature with regard to the use of different intravenous agents as supplements to inhalational anaesthesia in horses. The Part 2 of this review will focus in the use of opioids and α2 -agonists. Methods: Pubmed and Web of Science. Search terms: horse, inhalant anaesthesia, balanced anaesthesia, partial intravenous anaesthesia, opioids, morphine, pethidine, butorphanol, methadone, fentanyl, alfentanil, remifentanil, sufentanil, xylazine, romifidine, detomidine, medetomidine and dexmedetomidine. Conclusions: Different drugs and their combinations can be administered systemically...
Valverde A.Alpha-2 agonists, such as xylazine, clonidine, romifidine, detomidine, medetomidine, and dexmedetomidine, are potent analgesic drugs that also induce physiologic and behavioral changes, such as hypertension, bradycardia, atrioventricular block, excessive sedation and ataxia, all of which can potentially limit their systemic use as analgesics in some clinical cases. The use of medetomidine and dexmetomidine has been introduced for equine anesthesia/analgesia, and although not approved in this species, their increased specificity for alpha-2 receptors may offer some potential advantages over the...
Bryant CE, England GC, Clarke KW.The sedative effects in horses of the new alpha 2 agonist medetomidine were compared with those of xylazine. Four ponies and one horse were treated on separate occasions with two doses of medetomidine (5 micrograms/kg bodyweight and 10 micrograms/kg bodyweight) and with one dose of xylazine (1 mg/kg bodyweight) given by intravenous injection. Medetomidine at 10 micrograms/kg was similar to 1 mg/kg xylazine in its sedative effect but produced more severe and more prolonged ataxia, and one animal fell over during the study. Medetomidine at 5 micrograms/kg produced less sedation but a similar deg...
Bettschart-Wolfensberger R, Clarke KW, Vainio O, Aliabadi F, Demuth D.The pharmacokinetics of intravenous (i.v.) medetomidine (7 mcg kg(-1)) were best described by a two-compartment model in five ponies. Total body clearance was 4 (SD 0.60) 1 kg h,(-1)t(1/2alpha)7. 6 (0.91) minutes and t(1/2beta)51.3 (13.09) minutes. In one pony the one-compartmental model was best fit, and total body clearance was 4. 2 l kg h(-1)and t(1/2)was 11 minutes. Medetomidine plasma levels had fallen below the limits of quantification (0.05 ng ml(-1)) within 4 hours. Medetomidine 5 mcg kg(-1)i.v. followed by an infusion of 3.5 mcg kg h(-1)for two hours provided a constant level of sedat...
Grimsrud KN, Mama KR, Steffey EP, Stanley SD.To describe the pharmacodynamics and pharmacokinetics following an intravenous (IV) bolus dose of medetomidine in the horse. Methods: Prospective experimental trial. Methods: Eight, mature healthy horses age 11.7 ± 4.6 (mean ± SD) years, weighing 557 ± 54 kg. Methods: Medetomidine (10 μg kg(-1) ) was administered IV. Blood was sampled at fixed time points from before drug administration to 48 hours post administration. Behavioral, physiological and biochemical data were obtained at predetermined time points from 0 minutes to 24 hours post administration. An algometer was also used to measu...
Ringer SK, Kalchofner K, Boller J, Fürst A, Bettschart-Wolfensberger R.To compare the effects of two balanced anaesthetic protocols on end-tidal isoflurane (Fe'ISO), cardiopulmonary performance and quality of recovery in horses. Methods: Prospective blinded randomized clinical study. Methods: Sixty-nine client-owned horses, American Society of Anesthesiologists category I and II, undergoing elective surgery. Methods: The horses were premedicated with acepromazine (0.03 mg kg(-1)) IM 30-60 minutes before induction of anaesthesia and were randomly assigned to one of two treatments: in group L (37 horses) xylazine (1 mg kg(-1)) and in group M (31 horses) medetomidin...
Solano AM, Valverde A, Desrochers A, Nykamp S, Boure LP.Standing surgical procedures are performed commonly in horses under sedation. This approach minimises the morbidity/mortality risks associated with general anaesthesia. The use of a medetomidine and morphine combination has not been investigated in horses despite the usefulness of each drug individually. Objective: To determine the efficacy of a medetomidine and morphine combination to produce standing sedation with minimal cardiorespiratory changes and adequate analgesia for exploratory laparascopy in mature horses. Objective: The combination of medetomidine and morphine will induce reliable ...
Sacks M, Ringer SK, Bischofberger AS, Berchtold SM, Bettschart-Wolfensberger R.To compare the effects of two balanced anaesthetic protocols (isoflurane-dexmedetomidine versus medetomidine) on sedation, cardiopulmonary function and recovery in horses. Methods: Prospective, blinded, randomized clinical study. Methods: Sixty healthy adult warm blood horses undergoing elective surgery. Methods: Thirty horses each were sedated with dexmedetomidine 3.5 μg kg (group DEX) or medetomidine 7 μg kg (group MED) intravenously. After assessing and supplementing sedation if necessary, anaesthesia was induced with ketamine/diazepam and maintained with isoflurane in oxygen/air and ...
Bueno AC, Cornick-Seahorn J, Seahorn TL, Hosgood G, Moore RM.To determine the cardiopulmonary and sedative effects of medetomidine hydrochloride in adult horses and to compare those effects with effects of an equipotent dose of xylazine hydrochloride. Methods: 10 healthy adult female horses. Methods: 5 horses were given medetomidine (4 microg/kg of body weight, i.v.), and the other 5 were given xylazine (0.4 mg/kg, i.v.). Heart rate, respiratory rate, arterial blood pressures, pulmonary arterial blood pressures, and cardiac output were recorded, and sedation and ataxia scores were assigned before and every 5 minutes after drug administration for 60 minu...
Bettschart-Wolfensberger R, Kalchofner K, Neges K, Kästner S, Fürst A.To examine the clinical suitability of medetomidine-propofol infusions for total intravenous anaesthesia in horses. Methods: Fifty client-owned horses of mixed breed, age [mean +/- SD (range)] 6.6 +/- 4.4 (0.04-18) years, mass 478 +/- 168.3 (80-700) kg presented for a range of operations requiring general anaesthesia. Methods: Pre-anaesthetic medication was intravenous (IV) medetomidine 7 mug kg(-1). Anaesthesia was induced with IV ketamine (2 mg kg(-1)) and diazepam (0.02 mg kg(-1)). After endotracheal intubation, O2 was delivered (FiO2 > 0.85). Positive pressure ventilation was initiated if ...
Creighton CM, Lemke KA, Lamont LA, Horney BS, Riley CB.To compare the effects of xylazine bolus versus medetomidine constant rate infusion (MCRI) on cardiopulmonary function and depth of anesthesia in dorsally recumbent, spontaneously breathing, isoflurane-anesthetized horses. Methods: Prospective, randomized crossover study. Methods: 10 healthy adult Standardbreds. Methods: Horses were premedicated with xylazine or medetomidine IV. Anesthesia was induced with diazepam and ketamine and maintained with isoflurane for 150 minutes. For the xylazine treatment, end-tidal isoflurane concentration was maintained at 1.7%, and xylazine (0.2 mg/kg [0.09 mg/...
Kalchofner KS, Picek S, Ringer SK, Jackson M, Hässig M, Bettschart-Wolfensberger R.To determine, in mildly hypercapnic horses under isoflurane-medetomidine balanced anaesthesia, whether there is a difference in cardiovascular function between spontaneous ventilation (SV) and intermittent positive pressure ventilation (IPPV). Methods: Prospective randomized clinical study. Methods: Sixty horses, undergoing elective surgical procedures under general anaesthesia: ASA classification I or II. Methods: Horses were sedated with medetomidine and anaesthesia was induced with ketamine and diazepam. Anaesthesia was maintained with isoflurane and a constant rate infusion of medetomidine...
Abass M, Picek S, Garzón JFG, Kühnle C, Zaghlou A, Bettschart-Wolfensberger R.In horses castration with primary intention healing is usually performed under balanced inhalation anaesthesia. To optimise analgesia, the use of local anaesthesia was tested. Objective: To investigate the effect of local mepivacaine before castration with first intention healing under balanced medetomidine-isoflurane anaesthesia and flunixin meglumine, morphine analgesia on perioperative cytokine levels and pain in horses. Methods: Prospective blinded clinical study. Methods: Twenty stallions were randomly assigned to control or mepivacaine groups. Flunixin meglumine was administered before s...
Yamashita K, Wijayathilaka TP, Kushiro T, Umar MA, Taguchi K, Muir WW.The anesthetic and cardiopulmonary effects of midazolam, ketamine and medetomidine for total intravenous anesthesia (MKM-TIVA) were evaluated in 14 horses. Horses were administered medetomidine 5 microg/kg intravenously as pre-anesthetic medication and anesthetized with an intravenous injection of ketamine 2.5 mg/kg and midazolam 0.04 mg/kg followed by the infusion of MKM-drug combination (midazolam 0.8 mg/ml-ketamine 40 mg/ml-medetomidine 0.1 mg/ml). Nine stallions (3 thoroughbred and 6 draft horses) were castrated during infusion of MKM-drug combination. The average duration of anesthesia wa...
Bettschart-Wolfensberger R, Freeman SL, Jäggin-Schmucker N, Clarke KW.To determine the minimal infusion rate of propofol in combination with medetomidine for long-term anesthesia in ponies and the effects of atipamezole on recovery. Methods: 12 ponies. Methods: Ponies were sedated with medetomidine (7 microg/kg of body weight, IV). Ten minutes later, anesthesia was induced with propofol (2 mg/kg, IV). Anesthesia was maintained for 4 hours, using an infusion of medetomidine (3.5 microg/kg per hour, IV) and propofol at a rate sufficient to prevent ponies from moving after electrical stimulation. Arterial blood pressures and blood gas analysis, heart rates, and res...
Grimsrud KN, Ait-Oudhia S, Durbin-Johnson BP, Rocke DM, Mama KR, Rezende ML, Stanley SD, Jusko WJ.The present study characterizes the pharmacokinetic (PK) and pharmacodynamic (PD) relationships of the α2-adrenergic receptor agonists detomidine (DET), medetomidine (MED) and dexmedetomidine (DEX) in parallel groups of horses from in vivo data after single bolus doses. Head height (HH), heart rate (HR), and blood glucose concentrations were measured over 6 h. Compartmental PK and minimal physiologically based PK (mPBPK) models were applied and incorporated into basic and extended indirect response models (IRM). Population PK/PD analysis was conducted using the Monolix software implementing t...
Tapio H, Raekallio MR, Mykkänen A, Männikkö S, Scheinin M, Bennett RC, Vainio O.Medetomidine suppresses cardiovascular function and reduces gastrointestinal motility in horses mainly through peripheral α -adrenoceptors. Vatinoxan, a peripheral α -antagonist, has been shown experimentally to alleviate the adverse effects of some α -agonists in horses. However, vatinoxan has not been investigated during constant-rate infusion (CRI) of medetomidine in standing horses. Objective: To evaluate effects of vatinoxan on cardiovascular function, gastrointestinal motility and on sedation level during CRI of medetomidine. Methods: Experimental, randomised, blinded, cross-over stud...
Bettschart-Wolfensberger R, Dicht S, Vullo C, Frotzler A, Kuemmerle JM, Ringer SK.To test if the addition of butorphanol by constant rate infusion (CRI) to medetomidine-isoflurane anaesthesia reduced isoflurane requirements, and influenced cardiopulmonary function and/or recovery characteristics. Methods: Prospective blinded randomised clinical trial. Methods: 61 horses undergoing elective surgery. Methods: Horses were sedated with intravenous (i.v.) medetomidine (7 μg kg(-1)); anaesthesia was induced with i.v. ketamine (2.2 mg kg(-1)) and diazepam (0.02 mg kg(-1)) and maintained with isoflurane and a CRI of medetomidine (3.5 μg kg(-1) hour(-1)). Group MB (n = 31) receive...
Goodwin WA, Keates HL, Pearson M, Pasloske K.The use of alfaxalone and medetomidine administered as an i.v. infusion to maintain anaesthesia has not previously been reported in the horse. Objective: To investigate the use of alfaxalone in hydroxpropyl-beta-cyclodextrin (Alfaxan) and medetomidine infusion as a field anaesthetic for short-term surgical procedures in the horse. Objective: Alfaxalone-medetomidine anaesthesia is suitable for short-term field anaesthesia in horses. Methods: Eleven healthy colts underwent 45 min of anaesthesia with an i.v. infusion of alfaxalone (2 mg/kg bwt/h) and medetomidine (5 μg/kg bwt/h) for routin...
Wiederkehr A, Barbarossa A, Ringer SK, Jörger FB, Bryner M, Bettschart-Wolfensberger R. To assess drug plasma levels, preanesthetic sedation, cardiopulmonary effects during anesthesia and recovery in horses anesthetized with isoflurane combined with medetomidine or xylazine. Prospective blinded randomized clinical study. Sixty horses undergoing elective surgery. Thirty minutes after administration of antibiotics, flunixine meglumine or phenylbutazone and acepromazine horses received medetomidine 7 μg kg (group MED) or xylazine 1.1 mg kg (group XYL) slowly intravenously (IV) and sedation was assessed 3 min later. Anesthesia was induced with ketamine/diazepam and maintained wi...
Umar MA, Yamashita K, Kushiro T, Muir WW.To evaluate the cardiovascular effects of total IV anesthesia with propofol (P-TIVA) or ketamine-medetomidine-propofol (KMP-TIVA) in horses. Methods: 5 Thoroughbreds. Methods: Horses were anesthetized twice for 4 hours, once with P-TIVA and once with KMP-TIVA. Horses were medicated with medetomidine (0.005 mg/kg, IV) and anesthetized with ketamine (2.5 mg/kg, IV) and midazolam (0.04 mg/kg, IV). After receiving a loading dose of propofol (0.5 mg/kg, IV), anesthesia was maintained with a constant rate infusion of propofol (0.22 mg/kg/min) for P-TIVA or with a constant rate infusion of propofol (...
Bettschart-Wolfensberger R, Bowen IM, Freeman SL, Weller R, Clarke KW.To search for long-term total i.v. anaesthesia techniques as a potential alternative to inhalation anaesthesia. Objective: To determine cardiopulmonary effects and anaesthesia quality of medetomidine-ketamine anaesthesia induction followed by 4 h of medetomidine-propofol anaesthesia in 6 ponies. Methods: Sedation consisted of 7 microg/kg bwt medetomidine i.v. followed after 10 min by 2 mg/kg bwt i.v. ketamine. Anaesthesia was maintained for 4 h with 3.5 microg/kg bwt/h medetomidine and propofol at minimum infusion dose rates determined by application of supramaximal electrical pain stimuli. Ve...
Valverde A, Rickey E, Sinclair M, Rioja E, Pedernera J, Hathway A, Cruz A.The effects of lidocaine combined with medetomidine or lidocaine alone on cardiovascular function during anaesthesia and their effects on recovery have not been thoroughly investigated in isoflurane-anaesthetised horses. Objective: To determine the effects of an intraoperative i.v. constant rate infusion of lidocaine combined with medetomidine (Group 1) or lidocaine (Group 2) alone on cardiovascular function and on the quality of recovery in 12 isoflurane-anaesthetised horses undergoing arthroscopy. Objective: The combination would depress cardiovascular function but improve the quality of rec...
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...
Yamashita K, Muir WW, Tsubakishita S, Abrahamsen E, Lerch P, Izumisawa Y, Kotani T.To evaluate effects of infusion of guaifenesin, ketamine, and medetomidine in combination with inhalation of sevoflurane versus inhalation of sevoflurane alone for anesthesia of horses. Methods: Randomized clinical trial. Methods: 40 horses. Methods: Horses were premedicated with xylazine and anesthetized with diazepam and ketamine. Anesthesia was maintained by infusion of guaifenesin, ketamine, and medetomidine and inhalation of sevoflurane (20 horses) or by inhalation of sevoflurane (20 horses). A surgical plane of anesthesia was maintained by controlling the inhaled concentration of sevoflu...
Kälin I, Henze IS, Ringer SK, Torgerson PR, Bettschart-Wolfensberger R.Medetomidine partial intravenous anaesthesia (PIVA) has not been compared to xylazine PIVA regarding quality of recovery. This clinical retrospective study compared recoveries following isoflurane anaesthesia balanced with medetomidine or xylazine. The following standard protocol was used: sedation with 7 µg·kg medetomidine or 1.1 mg·kg xylazine, anaesthesia induction with ketamine/diazepam, maintenance with isoflurane and 3.5 µg·kg·h medetomidine or 0.7 mg·kg·h xylazine, and sedation after anaesthesia with 2 µg·kg medetomidine or 0.3 mg·kg xylazine. Recovery was timed and, using vi...
Bettschart-Wolfensberger R, Bowen MI, Freeman SL, Feller R, Bettschart RW, Nolan A, Clarke KW.To determine cardiopulmonary effects of total IV anesthesia with propofol and medetomidine in ponies and effect of atipamezole on recovery. Methods: 10 ponies. Methods: After sedation was induced by IV administration of medetomidine (7 microg/kg of body weight), anesthesia was induced by IV administration of propofol 12 mg/kg) and maintained for 4 hours with infusions of medetomidine (3.5 microg/kg per hour) and propofol 10.07 to 0.11 mg/kg per minute). Spontaneous respiration was supplemented with oxygen. Cardiopulmonary measurements and blood concentrations of propofol were determined during...
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...
