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.
Love EJ, Taylor PM, Murrell J, Whay HR, Waterman-Pearson AE.The aim of this randomised, observer-blinded, crossover study was to compare the effects of four treatments, administered intravenously to six horses: saline and saline; 10 µg/kg detomidine and 7.5 µg/kg buprenorphine; 20 µg/kg detomidine and 7.5 µg/kg buprenorphine; and 20 µg/kg detomidine and 10 µg/kg buprenorphine. Sedation was subjectively assessed and recorded on a visual analogue scale. Peak sedation and duration of sedation were investigated using a univariate general linear model with post-hoc Tukey tests (P<0.05). Increasing the dose of detomidine from 10 to 20 µg/kg increas...
Cruz FS, Carregaro AB, Machado M, Antonow RR.This study investigated the sedative, cardiopulmonary, and gastrointestinal effects produced by buprenorphine and xylazine given in combination to horses. Six healthy adult horses underwent 4 randomized treatments, with an interval of 1 wk between treatments. A control group was given a saline solution intravenously (IV) and the experimental groups received buprenorphine [10 μg/kg bodyweight (BW)] in combination with 1 of 3 different doses of xylazine: 0.25 mg/kg BW (BX25), 0.50 mg/kg BW (BX50), or 0.75 mg/kg BW (BX75), all of them by IV. Cardiopulmonary parameters were evaluated for 120 min ...
Coomer RP, Fowke GS, McKane S.To report the technique and results of cheek teeth repulsion in standing, sedated horses. Methods: Case series. Methods: Horses (n = 12), ponies (6). Methods: Medical records (2006-2009) of horses that had cheek tooth repulsion while standing were reviewed. Inclusion criteria included: maxillary or mandibular cheek tooth disease diagnosed by clinical and radiographic examination where attempted oral extraction failed necessitating repulsion. Horses were sedated and a local nerve block performed. Intraoperative radiographs facilitated instrument positioning and ensured repulsion of all dental r...
Love EJ, Taylor PM, Murrell J, Whay HR, Waterman-Pearson AE.The aim of this randomised, observer-blinded, crossover study was to compare the effects of six treatments, administered intravenously to six horses: saline and saline (S/S); detomidine and saline (D/S); detomidine and 5 µg/kg buprenorphine (D/B5); detomidine and 7.5 µg/kg buprenorphine (D/B7.5); detomidine and 10 µg/kg buprenorphine (D/B10); and detomidine and 25 µg/kg butorphanol (D/BUT). The detomidine dose was 10 µg/kg for all treatments in which it was included. Sedation was subjectively assessed and recorded on a visual analogue scale. Peak sedation, duration of sedation and the are...
Kaukinen H, Aspegrén J, Hyyppä S, Tamm L, Salonen JS.The objective of the study was to determine the absorption, bioavailability and sedative effect of detomidine administered to horses as an oromucosal gel compared to intravenous and intramuscular administration of detomidine injectable solution. The study was open and randomized, with three sequences crossover design. Nine healthy horses were given 40 μg/kg detomidine intravenously, intramuscularly or administered under the tongue with a 7-day wash-out period between treatments. Blood samples were collected before and after drug administration for the measurement of detomidine concentration...
Dimaio Knych HK, Steffey EP, Deuel JL, Shepard RA, Stanley SD.Yohimbine is an alpha 2 adrenergic receptor antagonist used most commonly in veterinary medicine to reverse the effects of the alpha 2 receptor agonists, xylazine and detomidine. Most notably, yohimbine has been shown to counteract the CNS depressant effects of alpha 2 receptor agonists in a number of species. The recent identification of a yohimbine positive urine sample collected from a horse racing in California has led to the investigation of the pharmacokinetics of this compound. Eight healthy adult horses received a single intravenous dose of 0.12 mg/kg yohimbine. Blood samples were co...
Klöppel H, Leece EA.To compare alfaxalone with ketamine for total intravenous anaesthesia in ponies undergoing castration. Methods: Prospective, randomised, blinded clinical study. Methods: Forty-two, 12-month-old Welsh Mountain ponies. Methods: Ponies were assigned randomly to receive ketamine or alfaxalone. After administration of romifidine 100 μg kg(-1) and butorphanol 50 μg kg(-1) intravenously (IV), sedation and response to tactile stimulation were scored. If sedation was insufficient, romifidine 30 μg kg(-1) was administered IV. Anaesthesia was induced with ketamine 2.2 mg kg(-1) or alfaxalone 1 mg kg(-...
Lacourt M, Marcoux M.To report use of a shielded hook bistoury developed for correction of epiglottic fold entrapment in standing sedated horses. Methods: Prospective clinical study. Methods: Standardbreds (n=8), 3-19 years of age. Methods: Epiglottic fold entrapment was corrected during standing sedation using a shielded hook bistoury passed nasally into the pharynx. Owners, trainers, and referring veterinarians were contacted by telephone to establish outcome. Results: Axial division of the entrapping epiglottic fold was successful in all horses. No short- or long-term complications occurred. Axial transection o...
Gardner RB, White GW, Ramsey DS, Boucher JF, Kilgore WR, Huhtinen MK.To determine whether sublingual detomidine gel administration to horses would be effective in providing an appropriate degree of sedation and restraint to facilitate completion of veterinary and husbandry procedures under field conditions. Methods: Multicenter, prospective, randomized, blinded, placebo-controlled clinical study. Methods: 270 client-owned horses known to require sedation or strong restraint to enable veterinary and husbandry procedures to be performed. Methods: Horses randomly received a single dose of detomidine gel (0.04 mg/kg [0.018 mg/lb]) or placebo gel administered sublin...
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...
Levine DG, Epstein KL, Ahern BJ, Richardson DW.To determine (1) if clinically useful concentrations of amikacin sulfate can be obtained in synovial fluid during regional limb perfusion (RLP) performed above the carpus in standing sedated horses and (2) to determine the efficacy of 3 tourniquet types (narrow rubber [NR], wide rubber [WR], pneumatic [PN]). Methods: Horses (n=9). Methods: Bilateral forelimb RLP with amikacin sulfate (2.5 g) were administered through the cephalic vein in standing sedated horses. Limbs were randomly assigned to the 3 tourniquet types (NR, WR, PN) applied above the carpus. Metacarpophalangeal synovial fluid was ...
Terry RL, McDonnell SM, Van Eps AW, Soma LR, Liu Y, Uboh CE, Moate PJ, Driessen B.Gabapentin is being used in horses although its pharmacokinetic (PK) profile, pharmacodynamic (PD) effects and safety in the equine are not fully investigated. Therefore, we characterized PKs and cardiovascular and behavioral effects of gabapentin in horses. Gabapentin (20 mg/kg) was administered i.v. or p.o. to six horses using a randomized crossover design. Plasma gabapentin concentrations were measured in samples collected 0-48 h postadministration employing liquid chromatography-tandem mass spectrometry. Blood pressures, ECG, and sedation scores were recorded before and for 12 h after gaba...
Pimenta EL, Teixeira Neto FJ, Sá PA, Pignaton W, Garofalo NA.Bradycardia may be implicated as a cause of cardiovascular instability during anaesthesia. Objective: Hyoscine would induce positive chronotropism of shorter duration than atropine, without adversely impairing intestinal motility in detomidine sedated horses. Methods: Ten minutes after detomidine (0.02 mg/kg bwt, i.v.), physiological saline (control), atropine (0.02 mg/kg bwt) or hyoscine (0.2 mg/kg bwt) were randomly administered i.v. to 6 horses, allowing one week intervals between treatments. Investigators blinded to the treatments monitored cardiopulmonary data and intestinal auscultation ...
Ho EN, Wan TS, Wong AS, Lam KK, Schiff PJ, Stewart BD.Bromide is a sedative hypnotic. Due to its potential use as a sedative or calmative agent in competition horses, a method to control bromide is needed. Colorimetric method had been employed in the authors' laboratory from 2003 for the semi-quantification of bromide in equine plasma samples. However, the method was found to be highly susceptible to matrix interference, and was replaced in 2008 with a more reliable inductively coupled plasma-mass spectrometry (ICP/MS) method. Equine plasma was protein-precipitated using trichloroacetic acid, diluted with nitric acid, and then submitted directly ...
Dimaio Knych HK, Steffey EP, Stanley SD.Yohimbine is an alpha 2 adrenergic receptor antagonist, which has been shown to counteract the CNS depressant effects of alpha 2 receptor agonists in a number of species. Recently, our laboratory identified yohimbine in the absence of detectable concentrations of an alpha 2 agonist in a regulatory sample collected from a horse racing in California. This coupled with anecdotal reports of CNS stimulation and documented reports of cardiovascular changes when administered in conjunction with an agonist led us to investigate the pharmacokinetics and pharmacodynamics of yohimbine when administered a...
Hubbell JA, Saville WJ, Bednarski RM.To determine the sedative, analgesic and anaesthetic drugs and techniques that are used by equine veterinarians. HYPOTHESIS OR OBJECTIVES: To provide equine veterinarians with information concerning veterinary use of anaesthetic techniques, a reflection of the collective experiences of the profession. Methods: A survey was conducted of those members of the American Association of Equine Practitioners (AAEP) with an electronic mail address on file with the organisation using proprietary, web-based software. The survey was comprised of 30 questions divided into 8 sections: nonsteroidal anti-infl...
Torres SM, Malone ED, White SD, Koch SN, Watson JL.Aural plaques affect at least 22% of horses and can be asymptomatic or cause ear sensitivity. Immunohistochemical and electron microscopy studies have shown a strong association between aural plaques and papilloma virus. The purpose of this study was to investigate the efficacy of imiquimod 5% cream, an immune response modifier with potent antiviral activity, in the treatment of equine aural plaques. Twenty-one horses were enrolled and 16 completed the study. Imiquimod 5% cream was applied three times a week, every other week. When both ears were affected only the worst affected ear was treate...
Kendall A, Mosley C, Bröjer J.Signs of tachypnea after sedation of febrile horses with alpha2-agonists have been noted previously but have not been further investigated. Objective: To examine the effects of xylazine and detomidine on respiratory rate and rectal temperature in febrile horses and to investigate if either drug would be less likely than the other to cause changes in these variables. Methods: Nine febrile horses and 9 healthy horses were included in the study. Methods: Horses were randomly assigned to sedation with xylazine 0.5 mg/kg or detomidine 0.01 mg/kg. Heart rate and respiratory rate were recorded before...
De Bont MP, Wilderjans H, Simon O.To describe a standing laparoscopic ovariectomy technique with intraabdominal ovarian dissection inside a specimen retrieval bag for removal of large pathologic ovaries through small incisions. Methods: Case series. Methods: Mares (n=43) aged 2-21 years and weighing 380-680 kg. Methods: Unilateral laparoscopic ovariectomy was performed on 43 standing sedated mares. Ovaries were approached via 3 portal sites, 2 in the paralumbar fossa and a 3rd between the 17th and 18th ribs on the ipsilateral side. Ovaries were dissected free using either a LiNA Tripol-bipolar laparoscopic forceps or a Ligasur...
Abuja GA, García-López JM, Doran R, Kirker-Head CA.To report outcome of horses after standing pararectal cystotomy for removal of uroliths. Methods: Case series. Methods: Horses (n=9) with cystic calculi. Methods: Medical records (December 1998-May 2007) of horses with cystic calculi that had standing pararectal cystotomy were reviewed. Signalment; urolith number, size, and type; surgical technique; sedation and analgesia protocols; intra- and postoperative complications and outcome were analyzed. Results: Uroliths (mean diameter, 6.37 cm; median, 6 cm; range, 3-10 cm) were removed intact without need for fragmentation. Eight (89%) horses had ...
Virgin J, Hendrickson D, Wallis T, Rao S.To compare the presence or absence of pain, pain-related behavioral responses, and hormonal responses to noxious stimuli during standing laparoscopic ovariectomy in mares sedated with continuous intravenous (IV) detomidine infusion and caudal epidural detomidine. Methods: A double blind prospective study. Methods: Mares (n=12) Methods: Mares were divided into 2 treatment groups; 6 were sedated using continuous IV detomidine infusion and 6 were sedated with caudal epidural detomidine. All mares received IV xylazine (0.33 mg/kg) and butorphanol tartrate (5 mg) premedication before detomidine adm...
Mama KR, Grimsrud K, Snell T, Stanley S.Detomidine hydrochloride is used to provide sedation, muscle relaxation and analgesia in horses, but a lack of information pertaining to plasma concentration has limited the ability to correlate drug concentration with effect. Objective: To build on previous information and assess detomidine for i.v. and i.m. use in horses by simultaneously assessing plasma drug concentrations, physiological parameters and behavioural characteristics. Objective: Systemic effects would be seen following i.m. and i.v. detomidine administration and these effects would be positively correlated with plasma drug con...
Boscan P, Rezende ML, Grimsrud K, Stanley SD, Mama KR, Steffey EP.To define the pharmacokinetic profile of propofol 5% microemulsion formulation in horses. Methods: First, propofol was administered as bolus injection (2 mg kg(-1)) to six xylazine-sedated horses. Secondly, after sedation and bolus injection, propofol was maintained with continuous infusion for 3 h [8.1 (sd 3.2) mg kg(-1) h(-1)] to the same six horses. Thirdly, in two horses, a commercial propofol was used for comparison. Response to noxious stimulation was used to evaluate analgesia. Venous blood samples were obtained to measure propofol plasma concentration using liquid chromatography-mass s...
Muir WW, Lerche P, Erichson D.Studies have demonstrated the clinical usefulness of propofol for anaesthesia in horses but the use of a concentrated solution requires further investigation. Objective: To determine the anaesthetic and cardiorespiratory responses to a bolus injection of 10% propofol solution in mature horses. Methods: Three randomised crossover experimental trials were completed. Trial 1: 6 horses were selected randomly to receive 10% propofol (2, 4 or 8 mg/kg bwt i.v.). Trial 2: 6 horses received 1.1 mg/kg bwt i.v. xylazine before being assigned at random to receive one of 5 different doses (1-5 mg/kg bwt) o...
Brosnan RJ, Steffey EP.We hypothesized that propofol can produce rapidly-reversible, dose-dependent standing sedation in horses. Methods: Prospective randomized, blinded, experimental trial. Methods: Twelve healthy horses aged 12 +/- 6 years (mean +/- SD), weighing 565 +/- 20 kg, and with an equal distribution of mares and geldings. Methods: Propofol was administered as an intravenous bolus at one of three randomized doses (0.20, 0.35 and 0.50 mg kg(-1)). Cardiovascular and behavioral measurements were made by a single investigator, who was blinded to treatment dose, at 3 minute intervals until subjective behavior s...
Hubbell JA, Sams RA, Schmall LM, Robertson JT, Hinchcliff KW, Muir WW.Increased doses of detomidine are required to produce sedation in horses after maximal exercise compared to calm or resting horses. Objective: To determine if the pharmacokinetics of detomidine in Thoroughbred horses are different when the drug is given during recuperation from a brief period of maximal exercise compared to administration at rest. Methods: Six Thoroughbred horses were preconditioned by exercising them on a treadmill. Each horse ran a simulated race at a treadmill speed that caused it to exercise at 120% of its maximal oxygen consumption. One minute after the end of exercise, h...
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...
Rohrbach H, Korpivaara T, Schatzmann U, Spadavecchia C.To evaluate and compare the antinociceptive effects of the three alpha-2 agonists, detomidine, romifidine and xylazine at doses considered equipotent for sedation, using the nociceptive withdrawal reflex (NWR) and temporal summation model in standing horses. Methods: Prospective, blinded, randomized cross-over study. Methods: Ten healthy adult horses weighing 527-645 kg and aged 11-21 years old. Methods: Electrical stimulation was applied to the digital nerves to evoke NWR and temporal summation in the left thoracic limb and pelvic limb of each horse. Electromyographic reflex activity was reco...
Hanly BK, Stokes AM, Bell AM, Johnson JR, Keowen ML, Paulsen DB, Sod GA, Moore RM.To determine the feasibility of performing serial laminar and skin biopsies on sedated horses and whether sampling affected adjacent tissues. Methods: 6 horses. Methods: Laminar tissues were harvested via biopsy through the hoof wall from healthy conscious horses via sedation and regional anesthesia. Eight specimens were collected at 4 time points during 24 hours from a single foot. Laminar biopsy specimens were harvested with a 6-mm-diameter biopsy punch after burring through the horny corium to the stratum medium. Skin biopsy specimens were collected from an area proximal to the coronary ban...
Walendy L, Goehring LS, Zablotski Y, Weyh T, Matiasek K, May A.Transcranial magnetic stimulation (TMS) has been successfully used in horses to evaluate function and integrity of descending motor pathways in patients affected by neurological gait abnormalities. In preceding studies, lengthening latency times (LT) of cranially evoked limb muscle potentials have been considered a reliable diagnostic parameter. Standardized settings use device output signal intensities of 100%. The aim of this study was to determine the effect of submaximal stimulation intensities (SI) and to determine the minimum coil output necessary to evoke motor unit potentials. As an ad...
Dodman NH, Shuster L, Court MH, Dixon R.Crib-biting in horses is a repetitive behavior pattern which may involve the activation of both narcotic receptors and dopamine receptors in the CNS. Crib-biting frequency, determined in 7 nontreated horses under controlled conditions, was usually linear for many hours and ranged from 0.3 to 14.9 bites/min. Intravenous or IM injections of narcotic antagonists decreased these rates to almost zero by about 20 minutes after the injection was given. The duration of the response to a single injection ranged from 20 minutes for naloxone to 4 hours or more for nalmefene and diprenorphine. Effective d...
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...
Harkins JD, Queiroz-Neto A, Mundy GD, West D, Tobin T.This report describes the development of a behaviour chamber and the validation of the chamber of measure locomotor activity of a horse. Locomotor activity was detected by four Mini-beam sensors and recorded on a data logger every 5 min for 22 h. Horses were more active during daytime than in the evening, which was at least partially related to human activity in their surroundings. To validate the ability of the chambers to detect changes in activity, fentanyl citrate and xylazine HCl, agents well-characterized as a stimulant and a depressant, respectively, were administered to five horses. Fe...
Kollias-Baker CA, Court MH, Williams LL.To determine the effects of yohimbine and tolazoline on the cardiovascular, respiratory and sedative effects of xylazine, four horses were sedated with xylazine and treated with either yohimbine, tolazoline or saline. Xylazine was administered as an intravenous (i.v.) bolus (1.0 mg/kg) followed by a continuous infusion at the rate of 12 micrograms/kg/min. Heart rate, respiratory rate, mean arterial pressure, arterial blood gases, and the chin-to-floor distance were recorded throughout the experiment. After 60 min, either yohimbine or tolazoline was administered i.v. in incremental doses until ...
Yamashita K, Muir WW, Tsubakishita S, Abrahamsen E, Lerch P, Hubbell JA, Bednarski RM, Skarda RT, Izumisawa Y, Kotani T.To compare the analgesic and cardiopulmonary effects of medetomidine and xylazine when used for premedication of horses undergoing general anesthesia. Methods: Randomized clinical trial. Methods: 40 horses. Methods: Twenty horses were premedicated with medetomidine (10 microg/kg [4.5 microg/lb], i.m.) and the other 20 were premedicated with xylazine (2 mg/kg [0.9 mg/kg], i.m.). Horses were then anesthetized with a combination of guaifenesin and ketamine; anesthesia was maintained with halothane. Additional doses of medetomidine or xylazine were given if horses were not sufficiently sedated at ...
Daunt DA, Dunlop CI, Chapman PL, Shafer SL, Ruskoaho H, Vakkuri O, Hodgson DS, Tyler LM, Maze M.Cardiopulmonary and behavioral responses to detomidine, a potent alpha 2-adrenergic agonist, were determined at 4 plasma concentrations in standing horses. After instrumentation and baseline measurements in 7 horses (mean +/- SD for age and body weight, 6 +/- 2 years, and 531 +/- 48.5 kg, respectively), detomidine was infused to maintain 4 plasma concentrations: 2.1 +/- 0.5 (infusion 1), 7.2 +/- 3.5 (infusion 2), 19.1 +/- 5.1. (infusion 3), and 42.9 +/- 10 (infusion 4) ng/ml, by use of a computer-controlled infusion system. Detomidine caused concentration-dependent sedation and somnolence. The...
Cooley PL.When compared with small domestic animals, the horse has unique ocular characteristics (complete bony orbit, well-developed eyelid muscles, a nasal and temporal gray limbal line, granulae iridica, paurangiotic fundus). Knowledge of normal equine ocular anatomy is essential for ocular lesion interpretation. It is important to obtain a full history and general examination before sedation, nerve blocks, or other diagnostic ophthalmic tests are performed. All ocular examinations should include a systematic evaluation of both the anterior and posterior segments. Selection of other diagnostic tests ...
Hubbell JA, Muir WW.The ability to shorten the duration of sedation would potentially improve safety and utility of detomidine. Objective: To determine the effects of tolazoline and atipamezole after detomidine sedation. Objective: Administration of tolazoline or atipamezole would not affect detomidine sedation. Methods: In a randomised, placebo-controlled, double-blind, descriptive study, detomidine (0.02 mg/kg bwt i.v.) was administered to 6 mature horses on 4 separate occasions. Twenty-five mins later, each horse received one of 4 treatments: Group 1 saline (0.9% i.v.) as a placebo control; Group 2 atipamezole...
Lund CM, Ragle CA, Lutter JD.An 11-year-old Arabian gelding was evaluated for hematuria, stranguria, and pollakiuria that had been observed for 1 week. Results: Transrectal palpation revealed a 5-cm firm round mass in the urinary bladder. Cystoscopy and transrectal ultrasonography confirmed the diagnosis of urinary bladder urolithiasis. Results: A multiportal transparalumbar fossa laparoscopic approach was selected for cystotomy and urolith removal. Cystotomy and urolith removal was performed with sedation and local anesthesia with the horse standing. No perioperative complications were observed. Urination returned to nor...
Dunay MP, Németh T, Makra Z, Izing S, Bodó G.In the present series of cases, 8 laparoscopic cryptorchidectomies and 4 laparoscopic ovariectomies were carried out in sedated standing horses. Sedation involved a lesser anaesthesiological risk than does general anaesthesia. As compared to laparotomic exposure, the minimally invasive laparoscopic intervention provided better visualisation, shorter operative time and faster recovery. The blood vessels supplying the testes and ovaries and the suspensory ligaments of the organs were sealed and cut with EnSeal®, an adaptive bipolar electrosurgical blood vessel- and tissue-sealing device. The cl...
DeRossi R, Sampaio BF, Varela JV, Junqueira AL.Epidural administration of bupivacaine and meperidine produces analgesia in several animal species and in humans. A prospective randomized study was conducted in 18 healthy horses to compare the effect of these 2 drugs administered by the epidural route. Animals were divided into 3 treatment groups of 6 animals each. All drugs were injected by the epidural route in all animals between the 1st and 2nd coccygeal vertebrae. Treatment 1 (BUP)--0.06 mg/kg of body weight of 0.5% hyperbaric bupivacaine; treatment 2 (MEP)--0.6 mg/kg of body weight of 5% meperidine; treatment 3 (SS)--0.9% saline soluti...
Miller C, Hoffman AM, Hunter J.Respiratory inductive plethysmography (RIP) can be used to obtain a valid measure of tidal volume in humans. This device also compares the contributions to ventilation of the thorax and abdomen. Although thoracoabdominal asynchrony is a prominent clinical feature for patients with airway obstruction, the accuracy of the RIP device to assess the severity of obstruction is unclear. This study analyzes how well RIP variables reflect the degree of a fixed external inspiratory plus expiratory resistive load in foals. Foals were employed because the species and age group are commonly afflicted with ...
Madry MM, Spycher BS, Kupper J, Fuerst A, Baumgartner MR, Kraemer T, Naegeli H.Compared to blood or urine, drugs can be detected for much longer periods in the long hair of horses. The aim of this study was to establish and validate a highly sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method for the detection and quantification of frequently prescribed opioids, sedatives and non-steroidal anti-inflammatory agents in the mane and tail hair of horses. Based on an average growth rate of about 2 cm per month, times of administration reported by horse owners or veterinary physicians were related to drug localizations in hair. Hair samples were collecte...
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...
Gozalo-Marcilla M, Moreira da Silva R, Pacca Loureiro Luna S, Rodrigues de Oliveira A, Werneck Fonseca M, Peporine Lopes N, Taylor PM, Pelligand L.The alpha(α) -agonist detomidine is used for equine sedation with opioids such as methadone. We retrieved the data from two randomized, crossover studies where detomidine and methadone were given intravenously alone or combined as boli (STUDY 1) (Gozalo-Marcilla et al., 2017, Veterinary Anaesthesia and Analgesia, 2017, 44, 1116) or as 2-hr constant rate infusions (STUDY 2) (Gozalo-Marcilla et al., 2019, Equine Veterinary Journal, 51, 530). Plasma drug concentrations were measured with a validated tandem Mass Spectrometry assay. We used nonlinear mixed effect modelling and took pharmacokinetic...
Nakayama SM, Ikenaka Y, Hayami A, Mizukawa H, Darwish WS, Watanabe KP, Kawai YK, Ishizuka M.Research on drug metabolism and pharmacokinetics in large animal species including the horse is scarce because of the challenges in conducting in vivo studies. The metabolic reactions catalyzed by cytochrome P450s (CYPs) are central to drug pharmacokinetics. This study elucidated the characteristics of equine CYPs using diazepam (DZP) as a model compound as this drug is widely used as an anesthetic and sedative in horses, and is principally metabolized by CYPs. Diazepam metabolic activities were measured in vitro using horse and rat liver microsomes to clarify the species differences in enzy...
Abuja GA, García-López JM, Doran R, Kirker-Head CA.To report outcome of horses after standing pararectal cystotomy for removal of uroliths. Methods: Case series. Methods: Horses (n=9) with cystic calculi. Methods: Medical records (December 1998-May 2007) of horses with cystic calculi that had standing pararectal cystotomy were reviewed. Signalment; urolith number, size, and type; surgical technique; sedation and analgesia protocols; intra- and postoperative complications and outcome were analyzed. Results: Uroliths (mean diameter, 6.37 cm; median, 6 cm; range, 3-10 cm) were removed intact without need for fragmentation. Eight (89%) horses had ...
Curtis RA, Hahn CN, Evans DL, Williams T, Begg L.Electrolaryngeography was used to study the latencies of the thoracolaryngeal adductor reflex in Thoroughbred horses with and without recurrent laryngeal neuropathy (RLN). Latencies were compared in horses with grades 1 and 2 RLN, diagnosed by endoscopy in resting horses. The reliability of the measurements, effect of sedation and correlations of latencies with age of the horse were also studied. There was no effect of sedation on reflex latency periods. The latency of the reflex period measured to a convolved peak of the electromyographic response was significantly different in horses with gr...
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...
Ruggles AJ, Ross MW, Freeman DE.The frontal, caudal maxillary, and rostral maxillary sinuses of 10 equine cadavers were examined endoscopically, and the findings were confirmed by sinusotomy. Similar endoscopic examinations were performed in five conscious, adult horses by using sedation and local anesthesia. Useful portals of entry for the arthroscope in adult horses were: for the frontal sinus, 60% of the distance in a lateral direction from midline to the medial canthus and 0.5 cm caudal to the medial canthus; for the caudal maxillary sinus, 2 cm rostral and 2 cm ventral to the medial canthus; and for the rostral maxillar...
Diez Bernal S, Studer N, Thormann W, Spadavecchia C, Levionnois O.To evaluate the effect of a romifidine infusion on antinociception and sedation, and to investigate its relationship with plasma concentration. Methods: Prospective, experimental, nonrandomized trial. Methods: A total of 10 healthy adult warmblood horses. Methods: Romifidine (loading dose: 0.08 mg kg, infusion: 0.03 mg kg hour) was administered intravenously over 120 minutes. Romifidine plasma concentrations were determined by capillary electrophoresis. Sedation quality and nociceptive thresholds were evaluated at regular time points before, during and after romifidine administration. The noci...
Hubbell JA, Sams RA, Schmall LM, Robertson JT, Hinchcliff KW, Muir WW.Increased doses of detomidine are required to produce sedation in horses after maximal exercise compared to calm or resting horses. Objective: To determine if the pharmacokinetics of detomidine in Thoroughbred horses are different when the drug is given during recuperation from a brief period of maximal exercise compared to administration at rest. Methods: Six Thoroughbred horses were preconditioned by exercising them on a treadmill. Each horse ran a simulated race at a treadmill speed that caused it to exercise at 120% of its maximal oxygen consumption. One minute after the end of exercise, h...
De Gasperi D, Dzierzak SL, Muir P, Vanderby R, Brounts SH.OBJECTIVE To assess the effects of sedation on results of acoustoelastography of the superficial digital flexor tendons (SDFTs) in clinically normal horses. ANIMALS 27 clinically normal horses. PROCEDURES For each horse, the pathology index (PI) for the SDFT of each thoracic limb was determined by use of acoustoelastography at 4 locations (5, 10, 15, and 20 cm distal to the accessory carpal bone). Horses were evaluated before and after they were sedated with a combination of detomidine hydrochloride (0.01 mg/kg, IV) and butorphanol tartrate (0.01 mg/kg, IV). A repeated-measures ANOVA was used ...
Stick JA, Chou CC, Derksen FJ, Arden WA.Isolated jejunal segments were perfused at a constant blood flow rate to determine simultaneously the effects of xylazine on intestinal vascular resistance, motility, compliance, and oxygen consumption in 12 anesthetized ponies. Xylazine was infused into the artery perfusing the intestinal segment (group 1), or into the jugular vein as a single IV bolus (group 2), or 3 times as IV boluses repeated at 10-minute intervals (group 3). Dose-response curves in group 1 indicated a biphasic response to the drug with vasoconstriction, increased motility, and increased oxygen consumption at lower doses ...
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...
Lee DF, Everest DJ, Cooley W, Chambers MA.Equine asthma, previously known as Recurrent Airway Obstruction (RAO) or Inflammatory Airway Disease (IAD), is an often-debilitating condition that may severely affect both performance and quality of life. Research is hindered by the low sample numbers of subjects recruited to studies, a consequence in part of the invasive nature of the sampling methods of bronchial brushing and biopsy. We present an alternative method of sampling equine airway epithelial cells, the 'nasal brush method' (NBM). Obtained by light brushing of the ventral meatus whilst the horse is under standing sedation, these c...
Hallman I, Tapio H, Raekallio M, Karikoski N.To assess the effects of an α-adrenoceptor agonist (detomidine) constant rate infusion (CRI) with and without an α-adrenoceptor antagonist (vatinoxan) CRI on blood insulin and glucose concentrations, heart rate, intestinal borborygmi, and sedation during and after infusion in horses. Methods: Randomized, blinded, crossover, experimental study. Methods: A total of nine healthy, adult Finnhorse mares. Methods: Horses were treated with an intravenous (IV) detomidine loading dose (0.01 mg kg), followed by CRI (0.015 mg kg hour), and the same doses of detomidine combined with an IV vatinoxan load...
Parhizkar P, Mohammadi R, Hashemi-Asl SM, Jalilzadeh-Amin G, Sarrafzadeh-Rezaei F.The aim of this study was to compare the sedative and cardiovascular effects of the combination of acepromazine-clonidine versus acepromazine-xylazine in horses. Four healthy cross-bred horses were included in the study. They were assigned to two treatments. In treatment I (T1), the animals received xylazine hydrochloride (1.00 mg kg) in combination with acepromazine maleate (0.05 mg kg) intravenously (IV). In treatment II (T2), the animals received intra-gastric administration of clonidine (0.002 mg kg) followed by acepromazine (0.05 mg kg; IV) after 60 min. Head height above the ground (HHAG...
Morris J, Hoang D.This article discusses a rare case of isolated xylazine overdose in a human, treated successfully with naloxone. Xylazine, typically used as a veterinary tranquilizer, acts as a potent α2 adrenergic agonist, leading to sedation, muscle relaxation, and potential respiratory depression. In this case, a female mistakenly injected herself with xylazine mistaking it for a different medication. The report discusses naloxone's role beyond opioid overdose, especially regarding substances causing central nervous system (CNS) depression via mechanisms similar to those of opioids. While naloxone is trad...
