Topic:Sedation
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.
Pharmacokinetics and pharmacodynamics of three intravenous doses of yohimbine in the horse. 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...
The use of sedatives, analgesic and anaesthetic drugs in the horse: an electronic survey of members of the American Association of Equine Practitioners (AAEP). 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...
The efficacy of imiquimod 5% cream (Aldara® in the treatment of aural plaque in horses: a pilot open-label clinical trial. 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...
Tachypnea and antipyresis in febrile horses after sedation with alpha-agonists. 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...
Standing laparoscopic ovariectomy technique with intraabdominal dissection for removal of large pathologic ovaries in mares. 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...
Pararectal cystotomy for urolith removal in nine horses. 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 ...
Comparison of intraoperative behavioral and hormonal responses to noxious stimuli between mares sedated with caudal epidural detomidine hydrochloride or a continuous intravenous infusion of detomidine hydrochloride for standing laparoscopic ovariectomy. 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...
Plasma concentrations, behavioural and physiological effects following intravenous and intramuscular detomidine in horses. 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...
Pharmacokinetic profile in relation to anaesthesia characteristics after a 5% micellar microemulsion of propofol in the horse. 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...
Anaesthetic and cardiorespiratory effects of propofol at 10% for induction and 1% for maintenance of anaesthesia in horses. 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...
Sedative effects of propofol in horses. 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...
Pharmacokinetics of detomidine administered to horses at rest and after maximal exercise. 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...
Pharmacokinetics of detomidine and its metabolites following intravenous and intramuscular administration in horses. 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...
Comparison of the effects of the alpha-2 agonists detomidine, romifidine and xylazine on nociceptive withdrawal reflex and temporal summation in horses. 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...
Use of serial laminar tissue collection via biopsy in conscious healthy horses. 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...
Evaluation of anesthesia recovery quality after low-dose racemic or S-ketamine infusions during anesthesia with isoflurane in horses. To compare anesthesia recovery quality after racemic (R-/S-) or S-ketamine infusions during isoflurane anesthesia in horses. Methods: 10 horses undergoing arthroscopy. Methods: After administration of xylazine for sedation, horses (n = 5/group) received R-/S-ketamine (2.2 mg/kg) or S-ketamine (1.1 mg/kg), IV, for anesthesia induction. Anesthesia was maintained with isoflurane in oxygen and R-/S-ketamine (1 mg/kg/h) or S-ketamine (0.5 mg/kg/h). Heart rate, invasive mean arterial pressure, and end-tidal isoflurane concentration were recorded before and during surgical stimulation. Arterial blood...
Behavioural and cardiorespiratory effects of a constant rate infusion of medetomidine and morphine for sedation during standing laparoscopy in horses. Standing surgical procedures are performed commonly in horses under sedation. This approach minimises the morbidity/mortality risks associated with general anaesthesia. The use of a medetomidine and morphine combination has not been investigated in horses despite the usefulness of each drug individually. Objective: To determine the efficacy of a medetomidine and morphine combination to produce standing sedation with minimal cardiorespiratory changes and adequate analgesia for exploratory laparascopy in mature horses. Objective: The combination of medetomidine and morphine will induce reliable ...
Effect of sedation with detomidine and butorphanol on pulmonary gas exchange in the horse. Sedation with alpha2-agonists in the horse is reported to be accompanied by impairment of arterial oxygenation. The present study was undertaken to investigate pulmonary gas exchange using the Multiple Inert Gas Elimination Technique (MIGET), during sedation with the alpha2-agonist detomidine alone and in combination with the opioid butorphanol. Methods: Seven Standardbred trotter horses aged 3-7 years and weighing 380-520 kg, were studied. The protocol consisted of three consecutive measurements; in the unsedated horse, after intravenous administration of detomidine (0.02 mg/kg) and after sub...
Effect of detomidine on visceral and somatic nociception and duodenal motility in conscious adult horses. To evaluate the effects of detomidine on visceral and somatic nociception, heart and respiratory rates, sedation, and duodenal motility and to correlate these effects with serum detomidine concentrations. Methods: Nonrandomized, experimental trial. Methods: Five adult horses, each with a permanent gastric cannula weighing 534 +/- 46 kg. Methods: Visceral nociception was evaluated by colorectal (CRD) and duodenal distension (DD). The duodenal balloon was used to assess motility. Somatic nociception was assessed via thermal threshold (TT). Nose-to-ground (NTG) height was used as a measure of sed...
Complications of laparoscopic surgery. This article describes surgical complications associated with laparoscopy, how to avoid them, how to recognize them if they do happen, and how to deal with them in the most expedient method possible. Complications of sedation, anesthesia, positioning, the general surgical approach, and complications associated with specific surgical procedures are examined. The best defense against surgical complications is a thorough training program and an understanding of anatomy that will help the surgeon work in the three-dimensional environment while being limited to two dimensions on the monitor. The au...
Vascular perfusion of reproductive organs in pony mares and heifers during sedation with detomidine or xylazine. To assess the vascular effects of detomidine and xylazine in pony mares and heifers, respectively, as determined in a major artery and by extent of vascular perfusion of reproductive organs. Methods: 10 pony mares and 10 Holstein heifers. Methods: Pony mares were assigned to receive physiologic saline (0.9% NaCl) solution (n = 5) or detomidine (3.0 mg/mare, IV; 5). Heifers were assigned to receive saline solution (5) or xylazine (14 mg/heifer, IM; 5). Color Doppler ultrasonographic examinations were performed immediately before and 10 minutes after administration of saline solution or sedative...
Comparison of pharmacopuncture, aquapuncture and acepromazine for sedation of horses. Pharmacopuncture, the injection of subclinical doses of drugs into acupoints reduces drug undesirable side effects, residues in animal consumption products and treatment costs in large animals. Acepromazine (Acp) produces several undesirable effects, such as hypotension. Previous studies with the injection of 1/10 of Acp dose in dog acupoints showed its advantage for sedation, minimizing undesirable effects. Eight horses were randomly submitted to four different treatment protocols according to a Latin Square double-blind design: (i) 0.1 ml kg(-1) of saline subcutaneously injected at the cervi...
Pharmacokinetics of butorphanol and evaluation of physiologic and behavioral effects after intravenous and intramuscular administration to neonatal foals. Despite frequent clinical use, information about the pharmacokinetics (PK), clinical effects, and safety of butorphanol in foals is not available. Objective: The purpose of this study was to determine the PK of butorphanol in neonatal foals after IV and IM administration; to determine whether administration of butorphanol results in physiologic or behavioral changes in neonatal foals; and to describe adverse effects associated with its use in neonatal foals. Methods: Six healthy mixed breed pony foals between 3 and 12 days of age were used. Methods: In a 3-way crossover design, foals received ...
Equine anesthesia: triple drip. Anesthetization of large animals, such as the horse, is a challenge for veterinarians and compounding pharmacists. This article discusses the technique of intravenous anesthesia by using a combination of xylazine and ketamine in the horse for short-term unconsciousness; a combination of xylazine, diazepam, and ketamine, for improved sedation and muscle relaxation; and a combination of xylazine, ketamine, and guaifenesin, referred to as Triple Drip, for the maximum 1-hour duration of unconsciousness. Compounding pharmacists that have the facilities and training required to prepare sterile compo...
Effects of sedation with acepromazine on echocardiographic measurements in eight healthy thoroughbred horses. Eight normal thoroughbred horses were examined by echocardiography before and 10 minutes after they had been sedated by the intravenous administration of 0.03 mg/kg acepromazine. There were significant (P<0.025) increases in the diameters of the pulmonary artery and the aorta, measured at end-systole, and in the thickness of the interventricular septum, measured at end-systole and end-diastole. In addition, there was a significant (P<0.001) decrease in the diameter of the left atrium measured at end-diastole. The remaining cardiac dimensions, all the indices of cardiac function, and the ...
A comparison of recovery times and characteristics with sevoflurane and isoflurane anaesthesia in horses undergoing magnetic resonance imaging. To compare recovery times and quality following maintenance of anaesthesia with sevoflurane or isoflurane after a standard intravenous induction technique in horses undergoing magnetic resonance imaging (MRI). Methods: Prospective, randomised, blinded clinical study. Animals One hundred ASA I/II horses undergoing MRI. Methods: Pre-anaesthetic medication with intravenous acepromazine and romifidine was followed by induction of anaesthesia with diazepam and ketamine. The animals were randomised into two groups to receive either sevoflurane or isoflurane in oxygen. Horses were subjectively scored...
Effect of acepromazine, butorphanol, or N-butylscopolammonium bromide on visceral and somatic nociception and duodenal motility in conscious horses. To evaluate effects of butorphanol, acepromazine, and N-butylscopolammonium bromide (NBB) on visceral and somatic nociception and duodenal motility in conscious, healthy horses. Methods: 6 adult horses. Methods: Visceral nociception was evaluated by use of colorectal distention (CRD) and duodenal distention (DD) threshold. Somatic nociception was evaluated via thermal threshold (TT). Nose-to-ground height, heart rate, and respiratory rate were also measured. Each horse received each treatment in randomized order; investigators were not aware of treatments. Butorphanol was administered IV as a ...
Transpalpebral eye enucleation in 40 standing horses. To report a technique for eye enucleation in standing sedated horses and to report outcome in 40 horses. Methods: Retrospective study. Methods: Horses (n=40) requiring eye enucleation. Methods: The eye was enucleated using a transpalpebral technique in 40 horses restrained in stocks and sedated. Anesthesia of orbital structures was provided by local nerve blocks and infiltration of the surgical site with local anesthetic solution. Results: Affected eyes were successfully enucleated with the horse standing. Short-term complications included moderate swelling (5 horses) and wound discharge (1). ...
Comparative study of epidural xylazine or clonidine in horses. To evaluate the cardiorespiratory and behavioural effects of epidural xylazine (XYL) or clonidine (CLO) in horses. Methods: Blinded, randomized experimental study. Methods: Twelve healthy Arabian yearling horses weighing 117-204 kg were randomly allocated into two groups: XYL (n = 6) and CLO (n = 6). Methods: An epidural catheter was inserted and a facial arterial catheter was placed and the next day the horses were restrained in stocks. Baseline values for heart (HR) and respiratory (RR) rates, arterial pressure and behavioural responses were evaluated before (T0) and 10, 20, 30, 45, 60, 90 a...
Sedation with detomidine and acepromazine influences the endoscopic evaluation of laryngeal function in horses. Endoscopy of the upper airways of horses is used as a diagnostic tool and at purchase examinations. On some occasions it is necessary to use sedation during the procedure and it is often speculated that the result of the examination might be influenced due to the muscle-relaxing properties of the most commonly used sedatives. Objective: To evaluate the effect of detomidine (0.01 mg/kg bwt) and acepromazine (0.05 mg/kg bwt) on the appearance of symmetry of rima glottidis, ability to abduct maximally the arytenoid cartilages and the effect on recurrent laryngeal neuropathy (RLN) grade. Methods: ...