Sedation in horses involves the administration of pharmacological agents to induce a state of calmness, relaxation, or sleepiness. This practice is commonly employed to facilitate veterinary procedures, diagnostic imaging, or transportation by reducing stress and movement in the animal. The primary sedatives used in equine medicine include alpha-2 adrenergic agonists, such as xylazine and detomidine, and opioids, like butorphanol. These agents act on the central nervous system to achieve the desired sedative effects. The choice of sedative and its dosage depend on various factors, including the horse's age, weight, health status, and the procedure's nature. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacology, efficacy, and safety considerations of sedation in equine practice.
Journée SL, de Meeus d'Argenteuil C, De Maré L, Boshuizen B, Vanderperren K, Journée LH, de Bruijn M, Bergmann W, Delesalle C.Spinal cord disorders are a common problem in equine medicine. However, finding the site of the lesion is challenging for veterinarians because of a lack of sensitive diagnostic methods that can assess neuronal functional integrity in horses. Although medical imaging is frequently applied to help diagnose corticospinal disorders, this approach does not reveal functional information. For the latter, transcranial magnetic stimulation (TMS) and more recently transcranial electrical stimulation (TES) can be useful. These are brain stimulation techniques that create either magnetic or electrical fi...
Racine J, O'Brien T, Bladon BM, Cruz AM, Stoffel MH, Haenssgen K, Rodgerson DH, Livesey MA, Koch C.To investigate the feasibility and complications associated with ceratohyoidectomy (CHE) in standing sedated horses unaffected (experimental horses) and standing sedated horses affected (clinical cases) with temporohyoid osteoarthropathy (THO). Methods: Case series. Methods: Six experimental horses and four clinical cases. Methods: Standing CHE was performed in six experimental horses euthanized 30 minutes (n = 3) and 7 days (n = 3) postoperatively. The four clinical cases were presented because of central facial nerve paralysis (n = 3), vestibular ataxia (n = 3), auricular hemorrhage (n =...
Moorman VJ, Bass L, King MR.To determine the effects of 3 α2-adrenergic receptor agonists (α2-ARAs), alone or in combination with butorphanol tartrate, on objective measurements of lameness in horses. Methods: 17 adult polo horses with naturally occurring forelimb or hind limb lameness (or both). Methods: In a crossover design, each horse received each protocol (saline [0.09% NaCl] solution [2 mL, IV] or xylazine hydrochloride [0.33 mg/kg, IV], detomidine hydrochloride [0.007 mg/kg, IV], or romifidine hydrochloride [0.033 mg/kg, IV] alone or in combination with butorphanol [0.007 mg/kg, IV]) in random order, with a was...
Tricyclic antidepressives, such as imipramine, indirectly induce ejaculation by increasing the noradrenaline concentration, which triggers an α-adrenergic response, whereas α-adrenergic agonists, such as xylazine and detomidine, directly trigger ejaculation by activating the α-1 adrenergic receptors. Furthermore, serum oxytocin concentrations in stallions increase drastically before ejaculation, but decline immediately thereafter, implicating the role of this hormone in emission. The objectives of the present study were to: 1) compare the efficiency of various protocols for inducing ex copu...
Hansen S, Stephansen MG, Fjeldborg J, van Galen G.Blood glucose concentrations fluctuate with stress, but little is known on how it is influenced by clinical procedures. The objective was to investigate the effect of clinical procedures on blood glucose concentration in healthy horses. Methods: Prospective, experimental study. Seven hospital-owned research horses were included in the study. A total of 4 horses were sampled either during a control sedation trial or during 3 different student workshops (prepurchase, oral, and rectal examination-the latter 2 with sedation). Blood samples were taken every 15 minutes and glucose concentration in w...
Seddighi R, Knych HK, Cox SK, Sun X, Moorhead KA, Doherty TJ.To determine the sedative effects and pharmacokinetic profile of detomidine when administered intravaginally as a gel formulation to horses. Methods: Randomized, crossover, masked experimental design. Methods: A group of six healthy adult mares (494 ± 56 kg). Methods: Mares were studied on two occasions and were administered either detomidine hydrochloride (10 μg kg) intravenously (treatment IV) or detomidine gel (40 μg kg) intravaginally (treatment IVG), separated by 1 week. Sedation, ataxia, muzzle-floor distance and heart rate (HR) were evaluated every 15 minutes for 240 minutes. Venous ...
Thibault CJ, Wilson DV, Robertson SA, Sharma D, Kinsley MA.To determine time to first passage of feces, total fecal piles and incidence of colic in the first 24 hours postprocedure in horses undergoing standing sedation with detomidine, or general anesthesia with or without detomidine. Methods: Retrospective cohort study. Methods: A total of 246 horses. Methods: Records of all horses that underwent standing sedation or general anesthesia between December 2012 and March 2016 were reviewed. Horses aged <6 months, admitted for colic or cesarean section, with inadequate data, and those not administered xylazine and/or detomidine were excluded. Records inc...
Raidal SL, McKean R, Ellul PA, Nielsen SG, Quinn CT.To characterize the effects of continuous positive airway pressure (CPAP) delivered by a commercial human CPAP device on respiratory function in foals with pharmacologically induced respiratory suppression. Methods: Prospective randomized, cross-over study comparing CPAP with spontaneous respiration and oxygen insufflation. Methods: University veterinary teaching hospital. Methods: Twelve foals born in consecutive seasons from a university teaching herd. Methods: Foals were randomized to receive 10 minutes of respiratory support by mask oxygen supplementation or CPAP as a first treatment after...
Frigerio MA, Gómez Cisneros D, Santiago Llorente I, Manso-Díaz G, López-Sanromán J.Chemical restraint is often used to perform diagnostic and minor surgical procedures; α2 -adrenoceptor agonists are the most commonly used drugs; however, the combination with an opiate can induce a profound sedation. There is a lack of kinematic studies examining the effects of the combination of these drugs on locomotor patterns. Objective: The objective of the study was to evaluate the duration of the effects of sedation with detomidine and detomidine combined with a low dose of butorphanol on the movement patterns of horses. Methods: The study was a controlled, randomised, blinded and cro...
Gray SM, Gutierrez-Nibeyro SD, Secor EJ.To report our experience with partial arytenoidectomy in sedated standing horses. Methods: Retrospective study. Methods: Fourteen client-owned adult horses. Methods: The medical records (2013-2017) of horses treated with unilateral partial arytenoidectomy while standing and sedated were reviewed. Demographics, endoscopic findings, previous treatments, and outcome after surgery were investigated and recorded. Results: Thirteen horses had unilateral left-sided recurrent laryngeal neuropathy (RLN) and 1 horse had bilateral RLN. Five horses had a previous failed prosthetic laryngoplasty. Left-side...
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...
Plunkett AH, Schoonover MJ, Young JM, Taylor JD, Holbrook TC.To determine the influence of location and movement on subtourniquet pressure (STP) generated by application of a wide-rubber tourniquet (WRT) on equine limbs. Methods: Randomized experimental cross-over design. Methods: Six standing, sedated horses. Methods: Horses were sedated with detomidine hydrochloride (0.2 μg/kg IV), and 4 investigators applied WRTs to the antebrachium (AB), gaskin (GK), and midmetacarpus (MC) of each horse in a predetermined, randomized order. Subtourniquet pressure was consequently measured at 10-minute intervals (T0, T10, T20, T30) for 30 minutes. Indirect systo...
Gozalo-Marcilla M, Luna SP, Gasthuys F, Pollaris E, Vlaminck L, Martens A, Haspeslagh M, Schauvliege S.To determine the required rate of a detomidine infusion (loading dose 5 μg kg; initial rate 12.5 μg kg hour) added to a constant infusion of methadone (0.2 mg kg; 0.05 mg kg hour) for sedation in standing horses and ponies undergoing elective surgeries with appropriate local anaesthetic techniques. Methods: Prospective, clinical study. Methods: Adult, healthy, client-owned, non-food-producing horses or ponies sedated for elective standing surgeries longer than 45 minutes. Methods: At baseline (in the stables before administration of sedative agents), at 10 minutes after sedation and every 5 ...
Torrent A, Spriet M, Espinosa-Mur P, Clark KC, Whitcomb MB, Borjesson DL, Galuppo LD.A technique for intra-arterial injection of mesenchymal stem cells (MSC) has been established for front limbs with the use of the median artery. This approach has been proposed for treatment of soft tissue injuries of the equine distal limb. A technique has not been validated yet for hindlimb injection. Objective: To assess the feasibility of injection of the cranial tibial artery in horses, and to evaluate the distribution and persistence of MSC after injection. Methods: In vivo experiment. Methods: In a first phase, the cranial tibial arteries of both hindlimbs of three research horses were ...
Harðardóttir H, Murison PJ, Blissitt K, Olason S, Clutton RE.Ketamine at 2.2 mg/kg given i.v. is often used to induce anaesthesia for surgical procedures in horses under field conditions. Commonly, additional doses are needed to complete the surgery. We hypothesised that surgical conditions would be improved when 5 mg/kg of ketamine was used to induce anaesthesia, while induction and recovery qualities would not differ from those when 2.2 mg/kg ketamine was used. Objective: To compare the anaesthetic effects of two ketamine doses (5 and 2.2 mg/kg) during field anaesthesia for castration of horses. Methods: Prospective, randomised, blinded, clinical stud...
Gozalo-Marcilla M, de Oliveira AR, Fonseca MW, Possebon FS, Pelligand L, Taylor PM, Luna SPL.Standing surgery avoids the risks of general anaesthesia in horses. Objective: To assess sedation, antinociception and gastrointestinal motility in standing horses after a detomidine loading dose and 2-h constant rate intravenous (i.v.) infusion, with or without methadone. Methods: Blinded, randomised, crossover with seven healthy adult cross-bred horses, three geldings and four females (404 ± 22 kg). Methods: Five i.v. treatments were administered to all horses with 1-week washout period: saline (SAL), detomidine low (2.5 μg/kg bwt + 6.25 μg/kg bwt/h) (DL) and high doses (5 μg/kg ...
Gozalo-Marcilla M, Luna SPL, Moreira da Silva R, Crosignani N, Lopes NP, Taylor PM, Pelligand L.Pharmacokinetic (PK)/pharmacodynamic (PD) modelling offers new insights to design protocols for sedation and analgesia in standing horses. Objective: To evaluate the parameters and interactions between detomidine and methadone when given alone or combined in standing horses. Methods: Randomised, placebo-controlled, blinded, crossover. Methods: Eight adult healthy horses were given six treatments intravenously: saline (SAL); detomidine (5 μg/kg bwt; DET); methadone (0.2 mg/kg bwt; MET) alone or combined with detomidine (2.5 [MLD], 5 [MMD] or 10 [MHD] μg/kg bwt). Venous blood samples were ob...
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 ...
Rowland AL, Navas de Solis C, Lepiz MA, Cummings KJ, Watts AE.Bone marrow is commonly collected from horses for regenerative medicine applications. Little information is available regarding pain experienced by the horse during bone marrow aspiration. The objective of this study was to characterize horse reaction and pain response during bone marrow aspiration (BMA) compared to a sham (SHAM) procedure. We hypothesized there would be significantly greater horse reaction or pain response measured by salivary cortisol, heart rate variability, and depth and duration of sedation between BMA and SHAM. Twelve university owned horses underwent a BMA and sham proc...
Schauvliege S, Cuypers C, Michielsen A, Gasthuys F, Gozalo-Marcilla M.To summarize the different methods used to assess sedation and/or adjust the dose or administration rate of alpha-2 agonists in horses and to propose an algorithm to adjust the administration rate of a constant rate infusion of an alpha-2 agonist in horses. Methods: PubMed and Web of Science; search terms: horse, sedation and score. Conclusions: Most authors distinguish between sedation depth, sedation quality and degree of ataxia. These three features are evaluated using scoring systems similar to those classically used to assess pain, i.e. simple descriptive scales, numerical rating scales (...
Ström L, Michanek M, Ekesten B.To investigate age-associated changes of flash visual evoked potentials (FVEPs) in sedated horses. Methods: Twenty-eight clinically healthy Standardbred Warmblooded trotters, aged 36 hours to 28 years. Methods: Light-adapted FVEPs and FERGs were recorded (An-vision RETIport, Roland-consult, Germany) in response to flash stimuli. Sedation was obtained using alpha-2-agonists intravenously. Akinesia of the eyelids was induced and pupils were dilated. Results: Reproducible FVEPs and FERGs were readily recorded from all foals and horses. The FVEP waveform included up to four positive components (...
Barakzai SZ, Wells J, Parkin TDH, Cramp P.Unilateral ventriculocordectomy (VeC) is frequently performed, yet objective studies in horses with naturally occurring recurrent laryngeal neuropathy (RLN) are few. Objective: To evaluate respiratory noise and exercising overground endoscopy in horses with grade B and C laryngeal function, before and after unilateral laser VeC. Methods: Prospective study in clinically affected client-owned horses. Methods: Exercising endoscopy was performed and concurrent respiratory noise was recorded. A left-sided laser VeC was performed under standing sedation. Owners were asked to present the horse for re...
Campoy L, Morris TB, Ducharme NG, Gleed RD, Martin-Flores M.Locoregional anaesthetic techniques can facilitate certain surgeries being performed under standing procedural sedation. The second and third spinal cervical nerves (C2, C3) are part of the cervical plexus and provide sensory innervation to the peri-laryngeal structures in people; block of these nerves might permit laryngeal lateralisation surgery in horses. Objective: To describe the anatomical basis for an ultrasound-guided cervical plexus block in horses. To compare this block with conventional local anaesthetic tissue infiltration in horses undergoing standing prosthetic laryngoplasty. Met...
Manneveau G, Lecallard J, Thorin C, Pamela H, Tessier C.To compare the topographic modifications and tactile sensitivity of the pharynx and larynx after administration of four sedative and analgesic protocols in standing horses. Methods: Experimental, observer-blinded, crossover study. Methods: Eight healthy mares. Methods: Five protocols were evaluated: 1) xylazine and butorphanol administered intravenously (IV); 2) detomidine and butorphanol administered IV; 3) xylazine administered IV and lidocaine topically; 4) detomidine administered IV and lidocaine topically and 5) no analgesia or sedation (control). Quality of sedation, head height and sudd...
Lucas Castillo JA, Gozalo-Marcilla M, Werneck Fonseca M, Possebon FS, da Rosa AC, de Araujo Aguiar AJ.Information on appropriate protocols for sedation of Nordestino donkeys is scarce. Objective: To evaluate the sedative and cardiorespiratory effects of low doses of intravenous (i.v.) xylazine with and without acepromazine in 'Nordestino' donkeys. Methods: Seven healthy female Nordestino donkeys (150 ± 18 kg) were included in this blinded, randomised, crossover experiment. Methods: Four treatments were administered, consisting of two i.v. injections, at baseline (T0, 1st injection) and 15 min later (T15, 2nd injection). Treatments included acepromazine 0.05 mg/kg bwt + saline (AS), saline + x...
Sandbaumhüter FA, Vimercati S, Thormann W, Mevissen M.The anesthetic ketamine is often combined with analgesics and benzodiazepines in equine medicine. Therefore, drug-drug interactions are possible. Enzyme kinetics for ketamine N-demethylation were determined using equine CYP3A94, CYP3A95 and CYP3A97, and the effect of medetomidine, diazepam and methadone on the ketamine metabolism was studied in vitro. Ketamine was incubated with the CYPs or equine liver microsomes (ELM) alone or in presence of medetomidine, diazepam and/or methadone for different times. Norketamine levels were determined using enantioselective capillary electrophoresis (CE) wi...
Tapio HA, Raekallio MR, Mykkänen A, Mama K, Mendez-Angulo JL, Hautajärvi H, Vainio OM.OBJECTIVE To compare the effects of MK-467 and hyoscine butylbromide on detomidine hydrochloride-induced cardiorespiratory and gastrointestinal changes in horses. ANIMALS 6 healthy adult horses. PROCEDURES Horses received detomidine hydrochloride (20 μg/kg, IV), followed 10 minutes later by MK-467 hydrochloride (150 μg/kg; DET-MK), hyoscine butylbromide (0.2 mg/kg; DET-HYO), or saline (0.9% NaCl) solution (DET-S), IV, in a Latin square design. Heart rate, respiratory rate, rectal temperature, arterial and venous blood pressures, and cardiac output were measured; blood gases and arterial plas...
Hibbs CD, Barrett PM, Dees DD.To determine intraocular pressure (IOP) reference intervals in eyes of healthy miniature donkeys (Equus africanus asinus) via rebound and applanation tonometry. Methods: Complete ophthalmic and physical examinations were performed by board-certified veterinary ophthalmologists. Inclusion criteria for animals participating in this study were dictated by the American Society for Veterinary Clinical Pathology (ASVCP) reference interval guidelines. Intraocular pressure estimates (TonoVet® and TonoPen XL® ) were obtained in both eyes. Forty animals (San Angelo group) received intramuscular xylazi...
Knych HK, Seminoff K, McKemie DS, Kass PH.Acepromazine is a tranquilizer used commonly in equine medicine. This study describes serum and urine concentrations and the pharmacokinetics and pharmacodynamics of acepromazine following intravenous, oral, and sublingual (SL) administration. Fifteen exercised adult Thoroughbred horses received a single intravenous, oral, and SL dose of 0.09 mg/kg of acepromazine. Blood and urine samples were collected at time 0 and at various times for up to 72 hr and analyzed for acepromazine and its two major metabolites (2-(1-hydroxyethyl) promazine and 2-(1-hydroxyethyl) promazine sulfoxide) using liqu...
Suarez-Fuentes DG, Tatarniuk DM, Caston SS, Kersh KD, Gillen AM, Hays AM.To compare outcomes after semitendinosus tenotomy performed under standing sedation versus general anesthesia. Methods: Retrospective case series. Methods: 20 horses with fibrotic myopathy of the semitendinosus muscle. Methods: Medical records (2002-2015) of horses undergoing tenotomy of the semitendinosus muscle for the treatment of fibrotic myopathy were reviewed. Signalment, history, affected muscles, restrain method, surgical procedures, and short-term outcome as well as complications were retrieved from records. Long-term outcome (gait and athletic function) was assessed at least 6 months...
König KS, Verhaar N, Hopster K, Pfarrer C, Neudeck S, Rohn K, Kästner SBR.Small intestinal strangulation associated with ischaemia-reperfusion injury (IRI) is common in horses. In laboratory animals IRI can be ameliorated by ischaemic preconditioning (IPC) and pharmacological preconditioning (PPC) with dexmedetomidine. The aim of this study was to determine the effect of PPC with dexmedetomidine or IPC in an equine model of small intestinal ischaemia-reperfusion (IR). In a randomized controlled experimental trial, 15 horses were assigned to three groups: control (C), IPC, and PPC with dexmedetomidine (DEX). All horses were placed under general anaesthesia and 90% je...
Skarda RT, Muir WW.Seven adult mares were used to determine the analgesic, CNS, and cardiopulmonary effects of detomidine hydrochloride solution after epidural or subarachnoid administration, using both regimens in random sequence. At least 1 week elapsed between experiments. A 17-gauge Huber point (Tuohy) directional needle was used to place a catheter with stylet into either the epidural space at the first coccygeal interspace or the subarachnoid space at the lumbosacral intervertebral junction. Catheters were advanced so that the tips lay at the caudal sacral (S5 to S4) epidural space or at the midsacral (S3 ...
Wilson DV, Bohart GV, Evans AT, Robertson S, Rondenay Y.To assess the effectiveness of a detomidine infusion technique to provide standing chemical restraint in the horse. Methods: Retrospective study. Methods: Fifty-one adult horses aged 9.5 ± 6.9 years (range 1-23 years) and weighing 575 ± 290.3 kg. Methods: Records of horses presented to our clinic over a 3-year period in which a detomidine infusion was used to provide standing chemical restraint were reviewed. Information relating to the types of procedure performed, duration of infusion, drug dosages and adjunct drugs administered was retrieved. Results: Detomidine was administered as an ini...
Matthews N, van Loon JPAM.The number of donkeys in the world may not be increasing but awareness of their use and concern for welfare and pain recognition and treatment are receiving increasing veterinary interest. Therefore, accurate information about anesthesia and analgesia in donkeys and mules is important to more equine practitioners. This review highlights the current knowledge on various anesthetic and analgesic approaches in donkey and mules. The authors emphasize that there is still much information that is not available about donkeys and mules; in many circumstances, the clinician must use available equine in...
Rossignol F, Vitte A, Boening J, Maher M, Lechartier A, Brandenberger O, Martin-Flores M, Lang H, Walker W, Ducharme NG.To describe the clinical experience with standing laryngoplasty in a series of horses mostly nonracing. Methods: Case series. Methods: Seventy-one client-owned horses. Methods: Medical records (April 2008-February 2014) of horses treated by standing laryngoplasty for abnormal respiratory noise and or poor performance were reviewed. Horses were included if they had a diagnosis of idiopathic right or left recurrent laryngeal neuropathy confirmed by videoendoscopy. All horses underwent a unilateral laryngoplasty with a unilateral or bilateral ventriculectomy or ventriculocordectomy. Follow-up end...
Frigerio MA, Gómez Cisneros D, Santiago Llorente I, Manso-Díaz G, López-Sanromán J.Chemical restraint is often used to perform diagnostic and minor surgical procedures; α2 -adrenoceptor agonists are the most commonly used drugs; however, the combination with an opiate can induce a profound sedation. There is a lack of kinematic studies examining the effects of the combination of these drugs on locomotor patterns. Objective: The objective of the study was to evaluate the duration of the effects of sedation with detomidine and detomidine combined with a low dose of butorphanol on the movement patterns of horses. Methods: The study was a controlled, randomised, blinded and cro...
Daunt DA, Steffey EP.Administration of alpha-2 agonists to horses produces a variety of behavioral effects (sedation, somnolence, analgesia), and physiological effects. One of the most significant beneficial effects of administering alpha-2 agonists is the degree of analgesia they provide. Alpha-2 agonists have been the mainstay of analgesia for colic pain in horses since their introduction to clinical veterinary medicine. The increased potency of the more recently introduced alpha-2 agonists allows the provision of analgesia for conditions not previously relieved by other drugs. Unfortunately, there are significa...
Barakzai SZ, Dixon PM.Trephination of the equine sinuses is a common surgical procedure in sedated standing horses. Standing sinus flap surgery has become increasingly popular in equine referral hospitals and offers several advantages over sinusotomy performed under general anesthesia, including reduced patient-associated risks and costs; less intraoperative hemorrhage, allowing better visualization of the operative site; and allows surgeons to take their time. Other minimally invasive surgical procedures include sinoscopic surgery, balloon sinuplasty, and transnasal laser sinonasal fenestration. Despite the proced...
Wagner AE, Mama KR, Steffey EP, Hellyer PW.To determine whether infusion of xylazine and ketamine or xylazine and propofol after sevoflurane administration in horses would improve the quality of recovery from anesthesia. Methods: 6 healthy adult horses. Methods: For each horse, anesthesia was induced by administration of xylazine, diazepam, and ketamine and maintained with sevoflurane for approximately 90 minutes (of which the last 60 minutes were under steady-state conditions) 3 times at 1-week intervals. For 1 anesthetic episode, each horse was allowed to recover from sevoflurane anesthesia; for the other 2 episodes, xylazine and ket...
Salonen JS, Vähä-Vahe T, Vainio O, Vakkuri O.The pharmacokinetics of detomidine, a novel analgesic sedative, was studied in the major target species after high (80 micrograms/kg) i.v. and i.m. doses. In addition, drug residues in some organs were determined. Concentrations were measured using a sensitive, detomidine-specific radio-immunoassay method. Rapid absorption following i.m. dosing occurred. Absorption half-lives were 0.15 h (horse) and 0.08 h (cattle). The mean peak concentration in the horse (51.3 ng/ml) was achieved in 0.5 h and in the cow (65.8 ng/ml) in 0.26 h. The areas under the concentration curve after i.m. dosing were 66...
Lavoie JP, Pascoe JR, Kurpershoek CJ.We studied the temporal changes in respiratory mechanics associated with xylazine administration (1.1 mg/kg of body weight, IV) in standing horses (experiment 1), and determined the effects of head and neck position (experiment 2) and atropine administration (experiment 3) on the observed changes. Thoroughbred geldings, 3 to 5 years old (5 in experiment 1, 4 in experiments 2 and 3) were used. Flow rates were obtained from a pneumotachograph and a differential transducer attached to a tight-fitting mask. Electronic integration of the flow signal gave tidal volume. Total pulmonary pressure (PL) ...
Risberg ÅI, Spadavecchia C, Ranheim B, Hendrickson EH, Lervik A, Haga HA.To elicit and evaluate the NWR (nociceptive withdrawal reflex) in 2 and 11 day old foals, to investigate if buprenorphine causes antinociception and determine if the NWR response changes with increasing age. The effect of buprenorphine on behaviour was also evaluated. Methods: Prospective, experimental cross-over trial. Methods: Nine Norwegian Fjord research foals. Methods: Buprenorphine, 10 μg kg(-1) was administered intramuscularly (IM) to the same foal at 2 days and at 11 days of age. The NWR and the effect of buprenorphine were evaluated by electromyograms recorded from the left deltoid m...
Grimsrud KN, Mama KR, Thomasy SM, Stanley SD.Detomidine is commonly used i.v. for sedation and analgesia in horses, but the pharmacokinetics and metabolism of this drug have not been well described. Objective: To describe the pharmacokinetics of detomidine and its metabolites, 3-hydroxy-detomidine (OH-detomidine) and detomidine 3-carboxylic acid (COOH-detomidine), after i.v. and i.m. administration of a single dose to horses. Methods: Eight horses were used in a balanced crossover design study. In Phase 1, 4 horses received a single dose of i.v. detomidine, administered 30 microg/kg bwt and 4 a single dose i.m. 30 microg/kg bwt. In Phase...
Murillo C, Weng HY, Weil AB, Kreuzer M, Ko JC.This study aimed to investigate the use of electroencephalography (EEG) for detecting brain activity changes perioperatively in anesthetized horses subjected to surgery. Twelve adult horses undergoing various surgeries were evaluated after premedication with xylazine and butorphanol, induction with ketamine, midazolam, and guaifenesin, and maintenance with isoflurane. The frontal EEG electrodes were placed after the horse was intubated and mechanically ventilated. The EEG data were collected continuously from Stage (S)1-transition from induction to isoflurane maintenance, S2-during surgery, S3...
Emanuel D, Kästner SBR, Delarocque J, Grob AJ, Bienert-Zeit A.The aim of this prospective clinical trial was to compare the influence of butorphanol, buprenorphine and levomethadone on sedation quality and postoperative analgesia in horses undergoing cheek tooth extraction. Fifty horses were assigned to three groups prior to oral cheek tooth extraction. Horses were treated with acepromazine, followed by a detomidine bolus, one of the three opioids and both a nerve block and gingival anaesthesia. During the surgery, sedation was maintained with a detomidine constant rate infusion. After surgery, the quality of sedation, surgical conditions and severity of...
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...
Röcken M, Mosel G, Stehle C, Rass J, Litzke LF.To describe a technique for, and outcome after, left- or right-sided laparoscopic-assisted nephrectomy in standing horses with unilateral renal disease. Methods: Clinical report. Methods: Horses (n=3) with unilateral renal disease. Methods: Horses were sedated with detomidine (0.01 mg/kg intravenously [IV]) and levomethadone (0.05 mg/kg IV). Paravertebral anesthesia and infiltration-anesthesia with 2% lidocaine were used to create a surgical field incorporating the 17th intercostal space and paralumbar fossa. Two separate, ipsilateral portals and a mini-laparotomy were used. The perirenal peri...
Church ML, Norman JC.The main objective was to record electroretinogram (ERG) parameters of normal thoroughbred mares using the HMsERG, a mini-Ganzfeld electroretinographic unit, and a contact lens electrode. The second objective was to determine whether IV detomidine hydrochloride at 0.015 mg/kg is consistently an effective choice for sedation of horses undergoing this ERG protocol. Methods: The study population consisted of 30 normal thoroughbred mares. ERG data were harvested using a protocol that included three different light intensities (10, 3000, and 10,000 mcd s/m(2)) and a 30-Hz flicker at 3000 mcd s/m(2)...
Guedes A, Knych H, Tucker L, Almeida DC, Baldo CF, Wendt-Hornickle E, Allweiler S.This study determined the pharmacokinetics and compared the clinical effects of xylazine and dexmedetomidine in horses recovering from isoflurane anesthesia. Six healthy horses aged 8.5 ± 3 years and weighing 462 ± 50 kg were anesthetized with isoflurane for 2 hr under standard conditions on two occasions one-week apart. In recovery, horses received 200 μg/kg xylazine or 0.875 μg/kg dexmedetomidine intravenously and were allowed to recover without assistance. These doses were selected because they have been used for postanesthetic sedation in clinical and research studies. Serial ...
Joubert KE, Briggs P, Gerber D, Gottschalk RG.Butorphanol and detomidine constitute an effective combination for sedation and analgesia in horses. This trial was undertaken to assess the effectiveness of this combination in donkeys. The detomidine and butorphanol were given intravenously one after the other. A dose of 10 microg/kg of detomidine and 25 microg/kg of butorphanol was used. Sedation is easily extended by additional doses of butorphanol. The average dose of detomidine was 11.24 microg/kg and that of butorphanol was 28.0 microg/kg. Four donkeys in the detomidine group required additional sedation and analgesia. Detomidine alone ...
Kritchevsky JE, Muir GS, Leschke DHZ, Hodgson JK, Hess EK, Bertin FR.In metabolically stable horses, alpha-2-agonists suppress insulin secretion with transient hyperglycemia and rebound hyperinsulinemia. In horses with insulin dysregulation (ID), the effect of alpha-2-agonists has not been investigated; however, both the alpha-2-agonist-induced suppression of insulin secretion and rebound hyperinsulinemia could have clinical relevance. Objective: In horses with ID, alpha-2-agonists will alter insulin and glucose dynamics. Methods: Seven horses with ID and 7 control horses. Methods: In this randomized crossover study, xylazine hydrochloride (1.1 mg/kg) or detomi...
Santonastaso A, Hardy J, Cohen N, Fajt V.In certain situations, an alternate route for parenteral drug administration in horses may be useful. The intra-osseous (IO) route may provide a safe alternative to the intravenous (i.v.) route for administration of sedatives to horses when the i.v. route is inaccessible or undesirable. Six adult horses were administered xylazine i.v. or IO in a block-randomized crossover design. For the i.v. trial, both jugular veins were catheterized, and one was used for xylazine administration, while the other was used for blood collection. For the IO trial, one jugular vein was catheterized for blood coll...
Carroll GL, Matthews NS, Hartsfield SM, Slater MR, Champney TH, Erickson SW.Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minute...
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...
Nankervis KJ, Williams RJ.The use of water treadmill exercise in horses is popular, although little is known about the physiological responses to this form of exercise. No information exists regarding the time taken to acclimate to water treadmill exercise compared to that of high-speed treadmill exercise, for both physiological and biomechanical parameters. Objective: To determine heart rate responses during acclimation to water treadmill exercise with and without sedation on first time exposure. Methods: All horses were exercised on a water treadmill at the walk for 15 min once a day for 4 days. Fourteen horses (mean...
Lizarraga I, Castillo-Alcala F.Combinations of α2 -adrenoceptor and opioid agonists are commonly used in equids, but little scientific information is available on donkeys. Objective: To compare the sedative and hypoalgesic effects of xylazine alone or in combination with different dosages of butorphanol in donkeys. Methods: Placebo-controlled, operator-blinded, randomised, crossover, Latin square study. Methods: Six donkeys received intravenous normal saline and normal saline (NS-NS); xylazine (0.5 mg/kg bwt) and normal saline (X-NS); xylazine and 10 μg/kg bwt butorphanol (X-B10); xylazine and 20 μg/kg bwt butorpha...
Rettig MJ, Leelamankong P, Rungsri P, Lischer CJ.Diagnostic analgesia is an integral part of equine lameness examinations, but is challenging to perform in uncooperative horses. Using sedation to facilitate this might, because of analgesic and ataxia-inducing effects, interfere with lameness evaluation. Objective: To evaluate whether sedation with low-dose xylazine would alter lameness amplitude as measured by body-mounted inertial sensors. Methods: Controlled experiment. Methods: Forty-four horses were randomly split into 2 groups. Lameness was measured using body-mounted inertial sensors before and after injection of xylazine (0.3 mg/kg b...
Ringer SK, Portier K, Torgerson PR, Castagno R, Bettschart-Wolfensberger R.To compare xylazine and romifidine constant rate infusion (CRI) protocols regarding degree of sedation, and effects on postural instability (PI), ataxia during motion (A) and reaction to different stimuli. Methods: Blinded randomized experimental cross-over study. Methods: Ten adult horses. Methods: Degree of sedation was assessed by head height above ground (HHAG). Effects on PI, A and reaction to visual, tactile and acoustic stimulation were assessed by numerical rating scale (NRS) and by visual analogue scale (VAS). After baseline measurements, horses were sedated by intravenous loading dos...
