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.
Kamerling SG, Cravens WM, Bagwell CA.1. Detomidine is a novel veterinary sedative analgesic which is thought to act by stimulation of alpha 2 adrenoreceptors. The present study was undertaken to determine the direction, time course, and dose-response relationship of detomidine on specific autonomic responses in the unanaesthetized horse. 2. Detomidine was administered intravenously to eight adult thoroughbred racehorses at doses of 0.010-0.040 mg kg-1, according to a double-blind Latin square crossover design. Cardiac and respiratory rates, pupil diameter and rectal temperature were monitored for 180 min postinjection. 3. Detomid...
Honnas CM, Wheat JD.Transnasal, axial division of the aryepiglottic fold was performed to correct entrapment of the epiglottis in 20 sedated, standing horses, using a hooked bistoury and topical anesthesia. Presenting complaints included decreased exercise tolerance or loss of racing performance, abnormal respiratory noise, and coughing. The surgical procedure was technically easy to perform with a minimum of instrumentation. The horses were rested an average of 18 days before race training or riding was resumed. Evaluation of racing records or contact with owners indicated that most affected horses competed succ...
Wood T, Weckman T, Woods WE, Tobin T, Dougherty J.Variable interval (VI) reinforcement scheduling is a specific type of operant conditioning that is sensitive to drug effects even when overt clinical signs of the drug have diminished. Six horses were conditioned to break a light beam with a head-bobbing movement and this behaviour was reinforced with a reward of clean oats (approximately 30 mg/reinforcement). Initial training procedures included familiarisation with the behavioural equipment and fixed-ratio reinforced scheduling. To establish baseline rates of behaviour, the horses were converted to a variable interval (60 secs) reinforcement...
Kamerling SG, Cravens WM, Bagwell CA.The effects of detomidine, a veterinary sedative analgesic, were studied in the horse. Novel objective techniques were employed to assess the analgesic and sedative potency of this compound. Intravenous doses of 0.010, 0.020 and 0.040 mg/kg were administered to eight adult Thoroughbred racehorses according to a double-blind crossover design. Analgesia was measured by determining the latency to onset of the skin twitch and hoof withdrawal reflexes following noxious thermal stimulation of the withers and fetlock, respectively. Sedation was assessed by quantifying spontaneous locomotor activity i...
Kohn CW, Muir WW.Comparison of the visceral analgesic effects of xylazine, morphine, butorphanol, pentazocine, meperidine, dipyrone, and flunixin in a cecal distention model of colic pain indicated that xylazine produces the most relief from abdominal discomfort. Repeated administration of xylazine may reduce visceral pain so effectively that the seriousness of abdominal disease is obscured. Xylazine decreased propulsive motility in the jejunum and pelvic flexure of healthy ponies. Morphine and butorphanol also gave relief from visceral pain in the cecal distention model. Morphine may inhibit colonic, and buto...
Singh AK, Mishra U, Ashraf M, Abdennebi EH, Granley K, Dombrovskis D, Hewetson D, Stowe CM.Chemical ionization- and electron impact ionization-selective ion monitoring provided a simple and sensitive method for measuring detomidine (Domosedan), a potent sedative-analgesic drug for horses and cattle. Chemical ionization was at least 10 times more sensitive than electron impact ionization. By using propranolol as an internal standard, we found that the recovery of detomidine from the extraction procedure used in this study was greater than 75% for plasma, whole blood, or urine samples. Approximately 68% of detomidine was bound to plasma protein and 53% was bound to red blood cells.
Plotka ED, Seal US, Eagle TC, Asa CS, Tester JR, Siniff DB.Forty-eight newly captured free-ranging feral stallions (Equus caballus) from two different locations and six captive stallions were immobilized using combinations of etorphine hydrochloride, xylazine hydrochloride and atropine sulfate with or without acepromazine. Six animals were immobilized twice, 1 mo apart. The drugs were administered either intramuscularly (n = 13) or intravenously (n = 44). Mean immobilization time (+/- SE) after intravenous (i.v.) injection of etorphine, xylazine and atropine was 55 +/- 4 sec (range 20 to 185 sec) compared to 708 +/- 131 sec (range 390 to 1,140 sec) fo...
Miller PJ, Martin IC, Kohnke JR, Rose RJ.The effects of acepromazine maleate (ACP), given orally in a paste form, were examined in six standard-bred geldings over a 12 hour period. Three dose rates, zero (placebo paste), 0.13 mg kg-1 and 0.26 mg kg-1, given before or after feeding, were investigated. The data were divided into two sampling periods for analysis, one from zero to 120 minutes and the other from four to 12 hours. Sedation was assessed by a score (TS score) based on general appearance, anal sphincter relaxation and penile protrusion. This TS score was significantly elevated 40 minutes after dosing with ACP, irrespective o...
Vakkuri O, Salonen JS, Leppäluoto J, Anttila M, Karjalainen A, Järvensivu P.A sensitive and specific radioimmunoassay was developed for detomidine, 4(5)-(2,3-dimethylbenzyl)imidazole. The antibodies were raised in rabbits against a conjugate of detomidine and bovine thyroglobulin prepared by diazo reaction. Detomidine was iodinated with chloramine-T and immunoreactive tracer was purified in cation exchange chromatography. The sensitivity of the RIA was 1.6 fmol/tube allowing direct detomidine measurements from minute serum and urine samples (0.1-0.2 microliter) as well as tissue homogenates (10 microliters). For concentrations below 16 pmol/ml chloroform extraction wa...
Clark ES, Semrad SD, Bichsel P, Oliver JE.Cystometrography and urethral pressure evaluations were performed in 7 horse mares and 5 pony mares before and after sedation with xylazine. Before sedation, mean (+/- SD) maximal bladder contraction pressure was 91.4 +/- 16.5 cm of H2O in horses and was 86.0 +/- 14.4 cm of H2O in ponies, and maximal urethral closure pressure was 49.1 +/- 19.4 cm of H2O in horses and 37.7 +/- 14.4 cm of H2O in ponies. A significant difference was not found between values of nonsedated vs sedated animals. Only values for threshold volume were significantly different (P less than 0.05) between nonsedated horses ...
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...
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 ...
Clarke KW, Taylor PM.Detomidine, given intravenously at doses of 5 to 30 (mean 13) micrograms/kg bodyweight (bwt), provided adequate sedation for a variety of clinical procedures in 93 per cent of administrations, and improved the ease of handling in the remaining animals. Side effects of ataxia and bradycardia were minimal at the lower dose rates. Higher doses were required for intramuscular use. In experimental trials 10 and 20 micrograms/kg bwt resulted in deep sedation and also significant hypertension and bradycardia of over 15 mins duration. Current literature on the use of detomidine in horses is reviewed.
Short CE, Stauffer JL, Goldberg G, Vainio O.Detomidine is a sedative-analgesic which has a pharmacological profile similar to xylazine. There is evidence that the sedative effects are mediated through alpha-2 adrenoceptors. Cardiopulmonary responses were determined using detomidine as the principal agent and as a preanesthetic prior to the induction of general anesthesia. Compatibility with guaifenesin, sodium thia-mylal and halothane were determined. As in the case of xylazine, detomidine produces a slowing of heart rates. This was found to be either sinus bradycardia or heart block. There may be a corresponding increase in systolic bl...
Kamerling SG, Dequick DJ, Weckman TJ, Tobin T.Sensitive methods for measuring the analgesic, physiological and behavioural effects of opioids in the horse have recently been developed. Fentanyl, a prototypic mu-opiate receptor agonist, has been previously shown to produce a syndrome characterized by marked analgesia and locomotor stimulation as well as tachycardia, tachypnoea and behavioural arousal. To determine whether other opiate receptors mediate some of the actions of the narcotic analgesics in the horse, an agent with activity at kappa- and to lesser extent mu-receptors was studied using a vigorous experimental protocol. Like fenta...
Singh AK, Mishra U, Ashraf M, Abdennebi EH, Granley K, Dombrovskis D, Hewetson D, Stowe CM.Chemical ionization- and electron impact ionization-selective ion monitoring provided a simple and sensitive method for measuring detomidine (Domosedan), a potent sedative-analgesic drug for horses and cattle. Chemical ionization was at least 10 times more sensitive than electron impact ionization. By using propranolol as an internal standard, we found that the recovery of detomidine from the extraction procedure used in this study was greater than 75% for plasma, whole blood, or urine samples. Approximately 68% of detomidine was bound to plasma protein and 53% was bound to red blood cells.
Knych HK, Steffey EP, Mitchell MM, Casbeer HC.The use of fentanyl is limited in adult horses, in part due to potential for central nervous system excitation. The pharmacokinetics and the plasma concentration-related behavioural actions of fentanyl have not been described for young foals. The goal of the present study was to describe the pharmacokinetics and behavioural effects of fentanyl following administration to the same group of foals at 3 different ages. Experimental study in healthy foals. Fentanyl was administered i.v. (4 μg/kg bwt) to a group of 9 foals on 3 separate occasions at 6–8, 20–22 and 41–42 days of age. Blood sam...
Cenani A, Brosnan RJ, Madigan S, Knych HK, Madigan JE.Propranolol has been suggested for anxiolysis in horses, but its sedation efficacy and side effects, both when administered alone and in combination with α-adrenoceptor agonists, remain undetermined. This study aimed to document the pharmacokinetics and pharmacodynamics of propranolol, romifidine and their combination. Methods: Randomized, crossover study. Methods: Six adult horses weighing 561 ± 48 kg. Methods: Propranolol (1 mg kg; treatment P), romifidine (0.1 mg kg; treatment R) or their combination (treatment PR) were administered intravenously with a minimum of 1 week between treatment...
Knych HK, Steffey EP, White AM, McKemie DS.Tramadol is an analgesic agent used in man and a number of veterinary species. The pharmacokinetics and behavioural effects of tramadol and its active metabolite have been described in mature horses, but not in young foals. Objective: To characterise the pharmacokinetics, metabolism and some induced behavioural and physiological responses following i.v. tramadol administration in the same group of foals on 4 different occasions, from a few days after birth to age 43 days. Methods: Experimental. Methods: Tramadol was administered i.v. (3 mg/kg bwt) to a group of 8 foals on 4 separate occasion...
Courtot D.At the request of the Service des Haras, our laboratory works on the toxicological problems of the sport-horse. These studies have resulted in the setting up of an anti-doping control for equestrian competitions of various types, not only flat racing. During events, horses, must be calm and docile to the riders' order. Frequently, the latter use tranquillizers to try and win events. The analytical method for the research and identification of these compounds is described. The technique involves successively: 1. alkalinisation of the sample - saliva, blood or urine after enzymatic hydrolysis. 2...
Dunlop CI.Physiologic similarities and differences between foals and adult horses, including response to pain, cardiopulmonary function, ability to compensate for dehydration and hemorrhage, and response to anesthetic drugs, are considered in this article. Preanesthetic evaluation, choice of anesthetic drugs, technique, and monitoring support requirements through to anesthetic recovery are based on these physiologic considerations. Anesthetic techniques discussed include drugs for premedication, parenteral or inhalational anesthetic induction, and maintenance using inhalational and parenteral anesthesia...
Nichols CL, Doherty TJ, Schumacher J, Jones PD, Sun X.To determine whether palmar digital nerve (PDN) blockade in horses with a combination of dexmedetomidine and mepivacaine would block the response to mechanical force applied to the digit longer than would anesthetizing these nerves with mepivacaine alone or dexmedetomidine alone. Methods: 8 mares with no signs of lameness. Methods: In a randomized, crossover, blinded, experimental study, both PDNs of the same forelimb of each horse were anesthetized by perineural injection with either 30 mg mepivacaine alone, 250 µg of dexmedetomidine alone, or 30 mg mepivacaine combined with 250 µg of dexme...
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...
Kamerling SG, Cravens WM, Bagwell CA.1. Detomidine is a novel veterinary sedative analgesic which is thought to act by stimulation of alpha 2 adrenoreceptors. The present study was undertaken to determine the direction, time course, and dose-response relationship of detomidine on specific autonomic responses in the unanaesthetized horse. 2. Detomidine was administered intravenously to eight adult thoroughbred racehorses at doses of 0.010-0.040 mg kg-1, according to a double-blind Latin square crossover design. Cardiac and respiratory rates, pupil diameter and rectal temperature were monitored for 180 min postinjection. 3. Detomid...
Nie GJ, Pope KC.Prolonged penile prolapse in horses has been reported in association with administration of phenothiazine tranquilizers, trauma, neuropathies, severe general debilitation or exhaustion, starvation, rabies, herpes myeloencephalitis, equine infectious anemia, and purpura hemorrhagica. A 5-year-old gelding was admitted for treatment of prolonged penile prolapse of 12 days' duration that developed after acepromazine maleate was administered to allow examination of a laceration that had resulted in severe blood loss. The horse was sedated, and the penis was replaced in the preputial cavity by use o...
Marzok M, Almubarak AI, Kandeel M, El-Khodery S.Epidural analgesia using the alpha-2 agonist detomidine (DE), alone or in combination with lidocaine (LD), is frequently employed for standing surgical procedures in horses, but its use has not been evaluated in donkeys. Methods: In a randomised controlled prospective trial, 24 healthy adult donkeys were assigned to four groups (n = 6), each receiving 40 μg/kg of DE, 0.22 mg/kg of LD, combined DE and LD (DELD) or 0.9% sterile normal saline epidurally. After epidural injection of each treatment, the onset, degree and duration of sedation and anatomical extension of anti-nociception were obse...
Stover BC, Caulkett NA.Dealing with an intractable horse is a reality for nearly every equine or mixed animal veterinarian. Establishing an adequate level of sedation prior to induction of anesthesia for various clinical procedures involves little margin for error regarding the safety of the veterinarian, handler, and patient. This is further compounded by the extreme difficulty of gaining venous access required to obtain rapid and reliable results. This case series describes a technique of intramuscular sedation used for field castration of 10 captive, formerly wild horses, which may be useful for various other typ...
Salonen JS, Vuorilehto L, Gilbert M, Maylin GA.Horse urine was investigated for metabolites by chromatography and mass spectrometry following the oral administration of the large animal analgesic sedative detomidine to two stallions and intravenous administration of [3H]-detomidine to a mare. Detomidine carboxylic acid and hydroxydetomidine glucuronic acid conjugate were identified in the urine after the oral doses. In addition, traces of free hydroxydetomidine were observed. About half of the radioactivity of [3H]-detomidine was excreted in the urine in 12 h after the i.v. dose (80 micrograms/kg). Most of the excretion occurred between 5 ...
Shrauner B, Blikslager A, Davis J, Campbell N, Law M, Lustgarten M, Prange T.The large size of the adult horse prevents the use of advanced imaging modalities in most areas of the axial skeleton, including the lumbosacral vertebral column. Traditional imaging techniques are frequently unable to pinpoint the underlying pathology in horses with caudal back pain. In man, lumbosacral epiduroscopy is used to diagnose and treat subjects with chronic back and leg pain. This technique may close the diagnostic gap in horses with similar clinical signs. Objective: To evaluate the safety and feasibility of lumbosacral epiduroscopy in the standing adult horse. Methods: Descriptive...
Ungemach FR.Doping in performance horses is defined as the "illegal application of any substance, except normal diet, that might modify the natural and present capacities of the horse at the time of the race." The prohibition of doping is mainly based on the protection of animals. Doping can be performed with various aims: "doping to win" can be regarded as the classical method by mobilization of overphysiological capacities. Such positive doping may be classified as an acute form using psychomotoric stimulants, as a chronic form using anabolic hormones, and as a paradoxical form using small doses of neur...
McMullen RJ, Gilger BC, Michau TM.To describe a surgical modification of deep lamellar endothelial keratoplasty (DLEK) and posterior lamellar keratoplasty (PLK) procedures, to facilitate surgery on standing horses under-sedation. Methods: Four client-owned horses, for which the owners declined surgery under general anesthesia, underwent standing corneal lamellar keratoplasty procedures for the treatment of deep corneal stromal abscesses. Methods: All four horses were placed in stocks and sedated with detomidine. Local eyelid and retrobulbar blocks were performed to provide local analgesia and akinesia, and each horse's head wa...
Duggan VE, MacAllister CG, Davis MS.An 18-month-old Quarter Horse filly was evaluated because of dorsal displacement of the soft palate associated with epiglottic dysfunction that caused exercise intolerance and an abnormal respiratory noise. The abnormality of the epiglottis was corrected by use of a sedative dose of xylazine hydrochloride. There was no familial predisposition to hyperkalemic periodic paralysis, which may cause similar laryngopharyngeal signs, and the horse did not respond to administration of acetazolamide. There was no known history of trauma that could have caused neuritis, which has also been suggested as a...
Modesto RB, Rodgerson DH, Masciarelli AE, Spirito M.This retrospective study describes placement of distal radial transphyseal screws in Thoroughbred yearlings with carpal varus deformities while standing, and identifes short- and long-term complications following the procedure. Data gathered from 2009 to 2013 identified 8 yearlings that met the inclusion criteria. Horses were sedated intravenously and a single 4.5-mm cortical screw was placed in the distal lateral radial physis following application of local anesthetic and surgical preparation of a pre-placed hole. All horses were evaluated weekly after surgery and screw removal was performed ...
Almonte H, Schumacher J, Johnson CR, Berk JT, Bell RP.To the authors' knowledge, the effect of a combination of butorphanol tartrate and detomidine hydrochloride on the laryngeal function and symmetry of the arytenoid cartilages in young Thoroughbred horses has not been examined. Therefore, this study aimed to examine the effects of administration of butorphanol and detomidine on left-to-right rima glottidis ratio (L:R RGR), cross-sectional area of the rima glottidis (CSARG) and grade of laryngeal function of Thoroughbred yearlings examined endoscopically at rest. Forty-six Thoroughbred yearlings underwent laryngeal video endoscopy, at rest, befo...
McClure SR, Taylor TS, Honnas CM, Schumacher J, Chaffin MK, Hoffman AG.Permanent tracheal stomas were created in seven sedated, standing horses with severe upper airway obstruction. After local anesthesia, a 3-cm by 6-cm rectangle of skin was removed from the ventral surface of the neck, 3 cm distal to the cricoid cartilage. The sternothyrohyoideus muscles were clamped proximally and distally, then transected to expose the tracheal rings. The ventral third of four tracheal rings was dissected from the tracheal mucosa that was then incised in a double "Y." Two layers of suture were used to achieve mucocutaneous closure. Stomas healed without serious complications;...
Ramsay EC, Geiser D, Carter W, Tobin T.To compare the effect of orally delivered detomidine on head posture when administered alone or in combination with two different food items, and to determine the serum concentrations of detomidine after oral delivery. Methods: Prospective randomized experimental study. Methods: Fifteen adult grade mares weighing 328-537 kg. Methods: The horses were randomly assigned to one of the three treatment groups (five horses each). The groups were given detomidine (0.06 mg kg): alone; mixed with 3 mL of an apple sauce and gum mixture; or mixed with 3 mL molasses. Head droop, measured before treatment a...
Hagedorn HW, Meiser H, Zankl H, Schulz R.Due to its tranquilizing properties, the tricyclic antidepressant doxepin may be misused as a doping agent in competition horses. Therefore, efficient analytical procedures are required to detect this drug in samples submitted for doping control. To screen for parent doxepin in equine blood and urine, a less specific method has been accepted employing gas chromatography (GC) combined with electron impact (EI) mass spectrometry (MS). The aim of this study was identification of doxepin metabolites providing more specific MS data to verify positives resulting from screening. Thus, after a horse w...
Knych HK, Stanley SD, McKemie DS, Steinmetz SJ.Romifidine is an alpha-2 adrenergic agonist used for sedation and analgesia in horses. As it is a prohibited substance, its purported use at low doses in performance horses necessitates further study. The primary goal of the study reported here was to describe the serum concentrations and pharmacokinetics of romifidine following low-dose administration immediately prior to exercise, utilizing a highly sensitive liquid chromatography-tandem mass spectrometry assay that is currently employed in many drug testing laboratories. An additional objective was to describe changes in heart rate and rhyt...
Lean NE, Sole-Guitart A, Ahern BJ.To investigate the feasibility and describe the clinical experience of performing laryngeal tie-forward (LTF) in standing horses unaffected (experimental) and affected (clinical) by intermittent dorsal displacement of the soft palate (iDDSP). Methods: Experimental study and case series. Methods: Five normal experimental controls and five client owned horses affected by iDDSP. Methods: Standing LTF was performed and evaluated in five experimental horses and five clinical cases diagnosed with iDDSP. Standing LTF was performed under endoscopic guidance with horses sedated and the surgical site de...
Ohnesorge VB, Deegen E, Jöchle W.Detomidine was used in this field trial effectively as a sedative and analgesic for laryngoscopic examinations in a total of 193 foals and 806 mature horses (Hanoverians). Detomidine was given either i.v. in foals 3 to 11 months old (20 micrograms/kg) and in mature horses (15 micrograms/kg), or i.m. in foals below 6 months of age (35 micrograms/kg). After i.v. administration, laryngoscopy was tolerated in more than 90% of all animals without additional use of a twitch, while in foals treated i.m. more than 70% required a twitch in order to enable this procedure. The effectiveness of detomidine...
Cribb NC, Arroyo LG, Bouré L.The use of a laparoscopic suction-irrigation device in 2 standing horses for lavage of the abdomen for the treatment of primary suppurative peritonitis is reported. Two horses were presented with a 1- to 2-week history of weight loss. Abdominocentesis revealed highly elevated total nucleated cell count. Peritoneal lavage systems were placed in both horses, but complications prevented adequate lavage. Both horses underwent standing laparoscopy; the dorsal abdomen was explored and the abdomen was profusely lavaged, using a suction-irrigation device. The procedure was efficient and allowed adequa...
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...
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...
Valverde A, Cribb N, Arroyo L.Twelve adult horses were randomly assigned to 2 groups in a prospective experimental trial. A pneumatic tourniquet (425 mmHg) was placed, under sedation, proximal to the carpus on one randomly chosen thoracic limb. A cephalic vein catheter was placed distal to the tourniquet to establish an intravenous regional limb perfusion technique (IVRLP) with morphine (0.1 mg/kg) diluted with saline 0.9% to 0.1 mL/kg, and the tourniquet left in place for 30 minutes. Horses were euthanized at 1 h (Group I) or 6 h (Group II) following the IVRLP and synovial fluid from the radiocarpal, intercarpal, metacarp...
Lean NE, Franklin SH, Ahern BJ.To describe left recurrent laryngeal neurectomy (LRLn) performed under standing sedation and evaluate the effect of LRLn on upper respiratory tract function using a high-speed treadmill test (HST). We hypothesized that (1) unilateral LRLn could be performed in standing horses, resulting in ipsilateral arytenoid cartilage collapse (ACC); and (2) HST after LRLn would be associated with alterations in upper respiratory function consistent with dynamic ACC. Methods: 6 Thoroughbred horses. Methods: The horses were trained and underwent a baseline HST up to 14 m/s at 5% incline until fatigue. Evalua...
