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.
Studer N, Bernal SD, Thormann W, Levionnois O, Spadavecchia C.To evaluate the antinociceptive effect of a bolus of intravenous levomethadone administered to horses during romifidine constant rate infusion (CRI). Methods: Prospective, randomized, masked, crossover experimental study. Methods: A group of eight adult Warmblood horses (seven geldings, one mare) aged 6.6 ± 4.4 years, weighing 548 ± 52 kg [mean ± standard deviation (SD)]. Methods: Levomethadone 0.1 mg kg or an equivalent volume of saline (control) was administered intravenously to standing horses 60 minutes after starting a romifidine CRI. Blood samples to quantify romifidine and levomethad...
Moss AL, Hritz RL, Hector RC, Wotman KL.To investigate the effects of orally administered trazodone on intraocular pressure (IOP), pupil diameter measured in the vertical plane (ie, vertical pupil diameter [VPD]), selected physical examination variables, and sedation level in healthy equids. Methods: 7 horses and 1 pony. Methods: Food was withheld for 12 hours prior to drug administration. After baseline (time 0) sedation scoring, physical examination, and measurement of IOP and VPD, equids received 1 dose (approx 6 mg/kg) of trazodone orally. Examination and measurement procedures were repeated 0.5, 1, 2, 4, 8, 12, and 24 hours aft...
Garcia AFS, Dória RGS, Arantes JA, Reginato GM, Neubauer FG, Ribeiro G.Although pharmacokinetic studies of drugs administered by intravenous regional limb perfusion (IRLP) to treat equine orthopedic infections suggest efficient drug distribution in the limbs, it remains unclear whether drug perfusion is affected by the position of the horse during the procedure. This study compared the perfusion of a radiopaque contrast into tissues of the extremities of horses maintained in standing and recumbent positions during an IRLP. Radiopaque contrast was administered through IRLP into the cephalic vein of 10 healthy adult horses under general anesthesia and right lateral...
Campoy L, Sedgwick SR.Procedural sedation has become popular for describing a semiconscious state that allows patients to be comfortable during certain surgical or diagnostic procedures. Sedation may be enhanced by locoregional anesthetic techniques to produce sufficient analgesia and muscle relaxation for surgery to occur. Sedation and local anesthesia for standing diagnostic and surgical procedures on the horse's head circumvents the potential complications of general anesthesia (particularly, complications related to recovery). However, the implementation of a locoregional anesthetic technique requires a thoroug...
Pouyet M, Bonilla AG.To describe the technique to perform diagnostic standing scapulohumeral joint needle arthroscopy with a 1.2-mm-diameter arthroscope in horses. Methods: Experimental study. Methods: Eight thoracic limbs in phase 1 and six horses in phase 2. Methods: In phase 1, the feasibility of the technique was evaluated by using a craniolateral arthroscopic approach. An evaluation of the visible structures of the scapulohumeral joint was performed with both a needle arthroscope and a 4-mm-diameter arthroscope. In phase 2, the technique was performed in six healthy sedated horses to validate the technique in...
Pigé C, Masseau I, Bonilla AG.The objective of this study was to determine if abdominal elevation could induce radiographically visible widening of the interspinous spaces in the thoracolumbar region of standing sedated horses and facilitate the surgical approach to the region. Radiographs centered on T13 and T18 were taken while applying different degrees of tension on a wide strap placed under the abdomen of 7 healthy horses. Then, the interspinous spaces between T11 and L2 were measured following a standardized method. The interspinous spaces widen radiographically between T11 to L2, except for T18-L1. Thus, the reporte...
Joyner RL, Liu CC, Cremer J, Carter RT, Lewin AC.Intravenous sedation is frequently necessary for ophthalmic examination in horses. Common sedation protocols have not been directly compared in terms of relative intraocular pressure (IOP) reduction, duration of IOP reduction and time to maximum IOP reduction. Objective: To compare the effects of standing sedation protocols on IOP. Methods: Randomised cross-over experiment. Methods: Twelve healthy horses received four intravenous sedation protocols with a 48 hours washout: 0.5 mg/kg xylazine and 0.01 mg/kg butorphanol (SED1); 10 µg/kg detomidine and 0.01 mg/kg of butorphanol (SED2); 10 ...
Alonso BB, La Rosa L, Carregaro AB, Gasthuys F, Schauvliege S.To examine the influence of detomidine or romifidine on recovery quality from isoflurane anesthesia, 78 anesthetic records were reviewed, from horses that had received romifidine (group R) during premedication [80-120 μg kg IV], anesthetic maintenance (40 μg kg hour IV), and recovery (20 μg kg IV) or detomidine (group D), at doses of 10-20 μg kg IV, 5 μg kg hour IV, and 2.5 μg kg IV, respectively. Duration of the different recovery phases, the number of attempts to sternal and standing, scores for transition to standing (TrSta), balance and coordination once standing (BC), and fina...
Guinnefollau L, Gee EK, Norman EJ, Rogers CW, Bolwell CF.Horses are used in practical teaching classes in many equine and veterinary science degree programmes to develop and refine the handling and clinical skills of students. In this study, the activities of 24 teaching horses grouped in three herds were investigated over an entire calendar year. Although also used for research and general husbandry, teaching-related activities were the predominant use of the horses. Herd B was used for a greater number of teaching sessions (median = 28, IQR = 27-29.5 per year) than herds M (median = 21, IQR = 20-21 per year) and T (median = 19.5, IQR = 13.75-25.5 ...
Oberhaus EL, Thompson DL, Kerrigan LE, Chapman AM.Stress or excitement is a concern when performing endocrine tests on fractious horses. Sedation may be a solution; however, perturbation of test results may preclude useful information. Thyrotropin-releasing hormone (TRH) is a known stimulator of prolactin, thyroid-stimulating hormone (TSH), melanocyte-stimulating hormone (MSH), and ACTH. Thyrotropin-releasing hormone-induced ACTH is a diagnostic tool for the assessment of endocrinopathies such as pituitary pars intermedia dysfunction. It is unknown if drugs commonly used for sedation alter endocrine responses. The objective of this study was ...
Morris TB, Lumsden JM, Dunlop CI, Locke V, Sommerauer S, Hurcombe SDA.The nociceptive blockade of locoregional anesthesia prior to surgical stimulation can decrease anesthetic agent requirement and thereby potential dose-dependent side effects. The use of an ipsilateral second and third cervical spinal nerve locoregional anesthetic block for prosthetic laryngoplasty in the anesthetized horses has yet to be described. Anesthetic records of 20 horses receiving locoregional anesthesia prior to laryngoplasty were reviewed and compared to 20 horses of a similar patient cohort not receiving locoregional anesthesia. Non-blocked horses were 11 times more likely to requi...
Delli-Rocili MM, Cribb NC, Trout DR, Thomason JJ, Valverde A.To compare the effectiveness of a paravertebral nerve block vs local portal blocks for laparoscopic closure of the nephrosplenic space in standing sedated research horses. Methods: Randomized clinical trial. Methods: Twelve horses were randomly allocated to two groups (n = 6 per group), paravertebral block of nerves T , L , and L or local blocks of the three laparoscopic portals. Methods: Horses were sedated with dexmedetomidine (4 μg/kg IV and constant rate infusion [CRI] of 2.5 μg/kg/h) and morphine (50 μg/kg IV and CRI of 30 μg/kg/h). According to group allocation, 20 mL of either lid...
de Grauw J, van Loon T.To compare the effects of two different doses of butorphanol combined with detomidine administered intravenously (IV) on quality of sedation, degree of ataxia and anaesthetic induction in horses. Methods: Randomized, blinded, clinical study. Methods: A total of 40 client-owned healthy warmblood horses scheduled for elective surgery under general anaesthesia. Methods: Horses were randomly allocated to be administered 8 μg kg-1 detomidine IV plus either 20 or 50 μg kg-1 butorphanol IV, with the principal investigator blinded to group allocation. Head height was measured before drug injection a...
Hopster K, Soma LR, Li X, Hopster-Iversen C, Boston RC, Driessen B.Intravenous (i.v.) bolus administration of xylazine (XYL) (0.5 mg/kg) immediately followed by a continuous rate infusion (CRI) of 1 mg kg hr for 2, 4, and 6 hr produced immediate sedation, which lasted throughout the duration of the CRI. Heart rate decreased and blood pressure increased significantly (p > .05) in all horses during the first 15 min of infusion, both returned to and then remained at baseline during the duration of the infusion. Compartmental models were used to investigate the pharmacokinetics of XYL administration. Plasma concentration-time curves following bolus an...
Hurcombe SD, Morris TB, VanderBroek AR, Habecker P, Wulster K, Hopster K.Horses underwent either cervical epidural space (CES) catheterization or subarachnoid space (SAS) catheterization while restrained in stocks, under deep sedation (detomidine and morphine) and local anesthesia (mepivacaine 2%) block. Catheters were placed under ultrasound guidance with visualization of the dura, SAS, and spinal cord between the first (C1) and second (C2) cervical vertebrae. Following sedation and sterile skin preparation, operator 1 placed under ultrasound guidance, a 6- or 8-inch Tuohy needle with the bevel oriented caudally. For CES, a 6-inch Touhy needle was used with the ha...
Pallarols NB, Lamuraglia R, Guglielminetti A, Ortiz de Elguea MF, Carossino M, Funcia JP.Xylazine and remifentanil in constant rate infusion (CRI) could be used for sedation in horses without adverse effects. The objective was to evaluate behavioral and cardiopulmonary effects of an intravenous (IV) infusion of xylazine and remifentanil for sedation in horses. Xylazine (0.8 mg/kg IV) followed after 3 minutes by a CRI of xylazine and remifentanil (0.65 mg/kg/h and 6 μg/kg/h, respectively) was administered in 10 healthy horses for 60 minutes. Sedation, ataxia, and cardiopulmonary, hematological, and blood gases variables were evaluated. Heart rate decreased significantly durin...
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...
Kadic DTN, Miagkoff L, Bonilla AG.To develop a technique for standing diagnostic needle arthroscopy of the radiocarpal and middle carpal joints in standing sedated horses. Methods: Experimental study. Methods: Six cadaveric forelimbs (phase 1) and six healthy horses (phase 2). Methods: In phase 1, six cadaveric forelimbs were used to assess needle arthroscopic evaluation of both joints. Six healthy horses were subsequently enrolled in phase 2 to validate the procedure in live animals. The joint was maintained in flexion with a custom-made splint and base. Results: In phase 1, needle arthroscopy allowed thorough evaluation of t...
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 ...
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...
Pearce CJ.Equine dentistry is a rapidly developing clinical specialty. It has benefitted from key advances in anatomical and physiological research, development of equipment and instrumentation, utilisation of standing sedation and anaesthesia protocols, a change towards minimally invasive surgical techniques, and the introduction of restorative and endodontic techniques translated from techniques used in human and canine dentistry. Anatomical research has provided further insight into the endodontic system of incisors and cheek teeth and how it changes throughout development with age. Studies of the pe...
Mendez-Angulo JL, Granados MM, Modesto R, Serrano-Rodriguez JM, Funes FJ, Quiros S, Gomez-Villamandos RJ, Zaldívar S, Trumble TN.Local anaesthetics are being combined clinically with amikacin in intravenous regional limb perfusion (IVRLP), with limited knowledge on the analgesia provided and its onset and duration of action after tourniquet application and release. Objective: To evaluate the systemic clinical effect, limb withdrawal to nociceptive stimulation, and plasma and synovial fluid concentrations after IVRLP with lidocaine or mepivacaine in standing sedated horses. Methods: Prospective, controlled, randomised, cross-over study. Methods: Six healthy adult horses were sedated and received IVRLP with lidocaine, mep...
Hector RC, Rezende ML, Mama KR, Hess AM.Post-anaesthetic sedation is administered to horses to improve recovery quality from inhalant anaesthesia and reduce the risk of catastrophic injury. A single dose of dexmedetomidine for this purpose has not been evaluated clinically. Objective: To determine whether dexmedetomidine improves recovery quality from sevoflurane anaesthesia compared to a previously studied dose of romifidine. Methods: Prospective, randomised, masked clinical trial. Methods: Ninety-nine, adult, client-owned horses anaesthetised for elective procedures completed the trial. Anaesthetic protocol was standardised. Horse...
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)...
Morgan JM, Ross MW, Levine DG, Stefanovski D, You Y, Robinson MA, Davidson EJ.To facilitate lameness evaluation, sedatives such as xylazine and acepromazine are regularly used in the clinical setting, despite concerns that they may confound lameness assessment. Objective: The objective of this study was to determine the effect of low doses of acepromazine and xylazine on subjective and objective lameness assessment. Methods: Randomised, blinded, crossover study. Methods: Six horses with experimentally induced solar pain were evaluated over a 1-hour period after treatment with intravenous xylazine (0.1 or 0.2 mg/kg), intravenous acepromazine (0.02 or 0.04 mg/kg), intra...
Secombe C, Waldmann AD, Hosgood G, Mosing M.Electrical impedance tomography (EIT) generates thoracic impedance images of the lungs and has been used to assess ventilation in horses. This technique may have application in the detection of changes in airflow associated with equine asthma. Objective: The objective was to determine if histamine-induced airflow changes observed with flowmetric plethysmography (Δflow) could also be explained using global and regional respiratory gas flow signals calculated from EIT signals. Methods: Experimental in vivo study. Methods: Six horses, sedated using detomidine were fitted with a thoracic EIT b...
Lewin AC, Liu CC, Camacho-Luna P, Alling C, Carter RT.It is currently unknown which of the two devices most commonly used in equine ophthalmology for intraocular pressure (IOP) estimation demonstrates the lowest inter-user and intra-user variation. Objective: To assess the inter-user and intra-user variation of two tonometers in sedated and unsedated horses. Methods: Randomised masked cross-over trial. Methods: Four examiners used the rebound (ICare TonoVet) and applanation (TonoPen ) tonometers to measure the intraocular pressure (IOP) in triplicate in 10 normal horses before and after sedation with xylazine. For inter-user variation, coefficien...
Pérez-Nogués M, Vaughan B, Phillips KL, Galuppo LD.To determine the safety and efficacy of caudal cervical articular process joint arthroscopy by using needle arthroscopy in standing sedated horses. Methods: Prospective experimental case series. Methods: Six adult horses. Methods: Three horses underwent exploration of bilateral C5-6 vertebral articular process joints and three bilateral C6-7 articular process joints by using a 1.2 × 65-mm needle arthroscope under standing sedation. The 16-gauge arthroscopic trocar and canula assembly was inserted in the desired articular process joint under ultrasonographic guidance without distention of ...
Miagkoff L, Bonilla AG.To investigate the use of a needle arthroscope for diagnostic tenoscopy of the carpal sheath in standing horses. Methods: Experimental study. Methods: Six forelimbs for the cadaveric part of the study and six horses for the in vivo part of the study. Methods: Six cadaveric limbs were used to perform carpal sheath tenoscopy with a 1.2-mm-diameter needle arthroscope (65 and 100 mm long), followed by tenoscopy with a 4-mm arthroscope through a standard proximolateral approach. Then, unilateral standing carpal sheath tenoscopy was performed in six healthy sedated horses with a 65-mm-long needle ...
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...
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...
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...
Hewes CA, Keoughan GC, Gutierrez-Nibeyro S.Enucleation was performed in 5 horses under local anesthesia and sedation with the horse standing. Minimal hemorrhage occurred during the surgical procedure, and there were no other reported complications. Standing enucleation is a surgery that is safe to perform in horses. L’énucléation a été réalisée chez 5 chevaux en position debout sous anesthésie locale et sédation. Une hémorragie minime est survenue pendant la procédure chirurgicale et il n’y a pas eu de complications rapportées. L’énucléation debout est une chirurgie sécuritaire chez le cheval. (Traduit par Docteur ...
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...
