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Topic:Detomidine
Detomidine is an alpha-2 adrenergic agonist commonly used as a sedative and analgesic in horses. It acts by binding to alpha-2 adrenergic receptors, resulting in sedation, muscle relaxation, and pain relief. This pharmacological agent is utilized in various veterinary procedures to facilitate handling, diagnostic imaging, and minor surgical interventions. Detomidine's effects on cardiovascular and respiratory systems are well-documented, and its use requires careful dosing and monitoring. This page gathers peer-reviewed research studies and scholarly articles that explore the pharmacodynamics, pharmacokinetics, and clinical applications of detomidine in equine medicine.
Anesthesia of horses with a combination of detomidine, zolazepam, tiletamine, and isoflurane immediately after strenuous treadmill exercise. To evaluate effects of strenuous exercise in adult horses immediately before anesthesia and to determine whether prior exercise affects anesthesia induction, recovery, or both. Methods: 6 healthy Thoroughbreds in good condition and trained to run on a treadmill, each horse serving as its own control. Methods: Horses ran on a treadmill until fatigued, then were sedated immediately with detomidine hydrochloride and anesthetized with a zolazepam hydrochloride-tiletamine combination. Anesthesia was maintained with isoflurane in oxygen for another 90 minutes. Blood samples were taken before, during...
Cardiorespiratory effects of a tiletamine/zolazepam-ketamine-detomidine combination in horses. To determine cardiorespiratory effects of a tiletamine/zolazepam-ketamine-detomidine (TZKD) combination in horses. Methods: 8 healthy adult horses. Methods: Horses were instrumented for measurement of cardiorespiratory, acid-base, and electrolyte values. Each horse was given xylazine (0.44 mg/kg of body weight, IV) 10 to 15 minutes prior to induction of recumbency by administration of the TZKD combination. Cardiorespiratory, acid-base, and electrolyte values were measured at 5-minute intervals for > or =30 minutes. Results: All horses became recumbent within 1 minute after IV administration of...
Detomidine-propofol anesthesia for abdominal surgery in horses. To evaluate propofol for induction and maintenance of anesthesia, after detomidine premedication, in horses undergoing abdominal surgery for creation of an experimental intestinal adhesion model. Methods: Prospective study. Methods: Twelve horses (424 +/- 81 kg) from 1 to 20 years of age (5 females, 7 males). Methods: Horses were premedicated with detomidine (0.015 mg/kg i.v.) 20 to 25 minutes before induction, and a propofol bolus (2 mg/kg i.v.) was administered for induction. Propofol infusion (0.2 mg/kg/min i.v.) was used to maintain anesthesia. The infusion rate was adjusted to maintain an...
Complications associated with administration of detomidine into the caudal epidural space in a horse. A 364-kg (800-lb) 15-month-old sexually intact cryptorchid male Quarter Horse was admitted to the veterinary teaching hospital for castration. The horse was placed in standing stocks, and a caudal epidural injection of 18 mg of detomidine hydrochloride (50 micrograms/kg [23 micrograms/lb] of body weight) was administered. Fifteen minutes after injection, the horse unexpectedly collapsed to the floor, first into sternal, and then into lateral, recumbency. Because the horse would not get up, the decision was made to perform the surgery with the horse under general anesthesia. The horse required ...
Cardiovascular effects of surgical castration during anaesthesia maintained with halothane or infusion of detomidine, ketamine and guaifenesin in ponies. Sixteen colts were premedicated with acepromazine and anaesthesia was induced with detomidine and ketamine. Ponies were randomly allocated to receive halothane (HAL) or infusion of detomidine, ketamine and guaiphenesin (DKG) to maintain anaesthesia. Heart and respiratory rate, ECG, mean arterial blood pressure (MABP), cardiac index (CI), blood gases and plasma cortisol, ketamine and guaiphenesin were measured. Surgical castration took place between 45 and 75 min and anaesthesia lasted 90 min. MABP with DKG was significantly higher than with HAL, and, with HAL, MABP increased from pre-surgery (...
Comparison of detomidine/ketamine and guaiphenesin/thiopentone for induction of anaesthesia in horses maintained with halothane. This prospective clinical study compared the physiological effects of two commonly used anaesthetic induction techniques in horses maintained with halothane. One hundred horses admitted for elective surgery were randomly allocated to receive either guaiphenesin (to effect) and thiopentone (5 mg/kg), or detomidine (20 microg/kg) and ketamine (2 mg/kg) for the induction of anaesthesia after acepromazine premedication. Anaesthesia was maintained with halothane in oxygen. There were no significant differences in breed, age, sex, weight, type of surgery and duration of anaesthesia between the group...
Effect of xylazine, detomidine, and a combination of xylazine and butorphanol on equine duodenal motility. To evaluate the effect on equine duodenal motility of some analgesic agents commonly used to treat colic. Methods: 4 healthy adult healthy horses--2 mares and 2 geldings--which were carrying an indwelling gastric cannula made of silastic rubber. One horse also carried 2 long-term indwelling bipolar electrodes that had been sutured onto the duodenum and jejunum. Methods: To ensure an empty stomach, solid food was withheld from horses for around 20 hours prior to an experiment. Using videoendoscopic guidance, an 8-F catheter with 3 small, discrete pressure sensors was passed through the gastric ...
Influence of atipamezole on effects of midsacral subarachnoidally administered detomidine in mares. To examine effects of atipamezole on detomidine midsacral subarachnoidally-induced analgesia, cardiovascular and respiratory activity, head ptosis, and position of pelvic limbs in healthy mares. Methods: 10 healthy mares. Methods: Using a randomized, blinded, crossover study design, mares received detomidine (0.03 mg/kg of body weight, diluted in 3 ml of CSF) midsacral subarachnoidally, followed by atipamezole (0.1 mg/kg [test]) or sterile saline (0.9% NaCl) solution (control), i.v. 61 minutes later and saline solution (3 ml, midsacral subarachnoidally) on a separate occasion, at least 2 weeks...
Effect of low-dose atropine administration on dobutamine dose requirement in horses anesthetized with detomidine and halothane. To determine whether a low dose of atropine is associated with decreased requirement for cardiovascular supportive treatment in horses given detomidine prior to maintenance of general anesthesia with halothane. Methods: 3 groups of 10 healthy horses. Methods: Detomidine (20 micrograms/kg of body weight, i.m.) was administered to all 30 horses. Then, 10 horses received atropine (0.006 mg/kg, i.v.) 1 hour after detomidine administration, 10 horses received atropine (0.012 mg/kg, i.m.) at the time of detomidine administration, and 10 horses served as a control group. Heart rate was measured prior...
Development and characterization of an equine behaviour chamber and the effects of amitraz and detomidine on spontaneous locomotor activity. 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...
Some effects of multiple administration of detomidine during the last trimester of equine pregnancy. Detomidine was given to 11 pregnant mares at 3 week intervals during the last trimester of pregnancy. Maternal and fetal electrocardiographs were recorded and fetal activity studied by transabdominal ultrasonography, before and 2 h (2, 5, 10, 20, 30, 60, 90 and 120 min) after injection. After parturition, the foals were examined and weighed. Maternal and fetal heart rate showed an initial decline after detomidine administration. Maternal heart rate in the treatment group were lower already 2 min after injection, but a reduction in fetal heart was first seen 5 min after detomidine administratio...
Laparoscopic cryptorchid castration in standing horses. This article describes a new technique for laparoscopic cryptorchid castration in standing horses. Methods: Prospective study. Methods: Eight horses aged 11 months to 3 years and weighing between 300 and 643 kg. Methods: Food was withheld for 24 to 36 hours, and then horses were sedated with detomidine HCl (0.02 to 0.03 mg/kg) and butorphanol tartrate (0.02 mg/kg). The paralumbar fossa region was desensitized with 2% mepivacaine in an inverted "L" pattern and caudal epidural anesthesia was administered with either xylazine (0.18 mg/kg diluted to 10 to 15 mL with 0.9% sodium chloride) or a comb...
Endocrine changes in cerebrospinal fluid, pituitary effluent, and peripheral plasma of anesthetized ponies. To investigate the effects of inhalation and total IV anesthesia on pituitary-adrenal activity in ponies. Methods: 9 healthy ponies: 5 geldings and 4 mares. Methods: Catheters were placed in the cavernous sinus below the pituitary gland and in the subarachnoid space via the lumbosacral space. After 72 hours, administration of acepromazine was followed by induction of anesthesia with thiopentone and maintenance with halothane (halothane protocol), or for the IV protocol, anesthesia induction with detomidine and ketamine was followed by maintenance with IV infusion of a detomidine-ketamine-guaif...
Systemic and local effects associated with long-term epidural catheterization and morphine-detomidine administration in horses. The purpose of this study was to determine the systemic and local effects associated with long-term epidural catheterization and epidural morphine-detomidine administration in horses. Methods: Development of systemic or local effects was assessed by placing caudal epidural catheters in study horses and administering injections through the catheters every 12 hours for 14 days. Methods: Ten horses with epidural catheters that received daily injections; six uncatheterized horses presented for euthanasia. Methods: Horses received either 0.2 mg/kg morphine sulfate and 30 micrograms/kg detomidine hy...
A pharmacodynamic study of propofol or propofol and ketamine infusions in ponies undergoing surgery. The pharmacodynamics of infusions of propofol alone (group 1) were compared with the pharmacodynamics of infusions of propofol and ketamine together (group 2) in eight ponies undergoing castration. Anaesthesia was induced with detomidine, 20 micrograms kg-1, followed by ketamine, 2.2 mg kg-1. Subsequently, a bolus dose of propofol, 0.5 mg kg-1, was administered intravenously to both groups, and an infusion of propofol was given for an average of 74 minutes to group 1, and an infusion of propofol and ketamine was given for 60 minutes to group 2. The mean (SD) infusion rates of propofol were 0.3...
The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies. 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...
Measurement of cardiac output in standing horses by Doppler echocardiography and thermodilution. Measurement of cardiac output by Doppler echocardiography were compared to simultaneous measurements by thermodilution in 9 conscious horses. In the Doppler technique, mean blood flow velocities for estimation of cardiac output were recorded from the aorta and pulmonary artery. The flow area of each vessel was calculated from the vessel diameter, measured from a 2-dimensional ultrasound image. Differences in the site and method of measuring the vessel diameter altered the estimation of cardiac output by the Doppler method. Cardiac output was modified by the i.v. infusion of 4 micrograms/kg bwt...
Electrically induced blink reflex in horses. The electrically induced blink reflex was studied electromyographically in 21 healthy adult, detomidine-sedated horses. Using surface electrodes, the supraorbital nerve was electrically stimulated at the supraorbital foramen. The responses were recorded from the ipsilateral and contralateral orbicularis oculi muscles with concentric needle electrodes inserted in the lateral aspect of the ventral eyelids. Ipsilateral and contralateral recordings were made on successive stimulations of the same side of the face, maintaining a constant stimulus intensity. The electromyographically recorded respon...
Cardiovascular and respiratory effects of detomidine in isoflurane-anaesthetised horses. Anaesthesia was induced in horses (n = 6) with a mixture of thiopentone and guaiphenesin and maintained by mechanical ventilation with a mixture of oxygen, air and isoflurane. Inspiratory and end-expiratory concentrations of oxygen, carbon dioxide and isoflurane were measured. Electrocardiography was used to evaluate heart rate and rhythm. Mean systemic arterial pressure (SAPm), pulmonary artery pressure (PAPm), right atrial pressure (RAPm) and pulmonary capillary wedge pressure (PCWP) were measured directly. Cardiac output was determined using the thermodilution method. Microcirculation in th...
Efficacy of an epidural combination of morphine and detomidine in alleviating experimentally induced hindlimb lameness in horses. Amphotericin B-induced synovitis of the left tarsocrural joint was used to create a grade 3 of 4 lameness in 11 horses. Caudal epidural catheters were placed and advanced to the lumbosacral region. Baseline heart and respiratory rates were recorded and horses were videotaped at a walk and trot. Morphine sulphate (0.2 mg/kg) and detomidine hydrochloride (30 micrograms/kg) were administered to treated horses (n = 8) through the epidural catheter; an equivalent volume of physiologic saline solution was administered to control horses (n = 3) through the catheter. At hourly intervals after epidural...
Alpha 2 adrenoceptor agonists in the horse–a review. In recent years the usefulness of the alpha 2 adrenoceptor agonist drugs has been recognized in equine practice. Several agents have become available and are now licensed for use in a number of countries. The principle actions of all alpha 2 adrenoceptor agonists are similar, in that they produce a reduction in heart rate and alteration of heart rhythm, an initial hypertension followed by a prolonged hypotension, a decrease in the cardiac output and respiratory depression. For clinical purposes, these agents produce sedation and analgesia, they are useful for premedication and markedly potenti...
Comparison of antinociceptive, cardiovascular, and respiratory effects, head ptosis, and position of pelvic limbs in mares after caudal epidural administration of xylazine and detomidine hydrochloride solution. To examine and compare effects of 2 alpha 2-adrenergic receptor agonists, xylazine and detomidine, administered into the sacrococcygeal epidural space to induce safe and effective perineal analgesia on cardiovascular and respiratory functions, head ptosis, and position of pelvic limbs in healthy mares. Methods: 8 healthy mares. Methods: Blood samples were drawn and systemic hemodynamics were determined, including cardiac output and pulmonary arterial, systemic arterial, and right atrial pressures. Two-way ANOVA with repeated measures was used to detect significant (P < 0.05) differences bet...
Cardiorespiratory, endocrine and metabolic changes in ponies undergoing intravenous or inhalation anaesthesia. Six Welsh gelding ponies (weight 246 +/- 6 kg) were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) followed by 0.02 mg/kg of detomidine i.v. Anaesthesia was induced with 2 mg/kg of ketamine i.v. Ponies were intubated and lay in left lateral recumbency. On one occasion anaesthesia was maintained for 2 h using 1.2% halothane in oxygen. The same group of ponies were anaesthetized 1 month later using the same induction regime and anaesthesia was maintained with a combination of detomidine, ketamine and guaiphenesin, while the ponies breathed oxygen-enriched air. Electrocardiogra...
Evaluation of detomidine-induced analgesia in horses with chronic hoof pain. Detomidine (10, 20 and 40 micrograms/kg i.v.) and saline were administered to eight adult horses with hoof pain and lameness associated with chronic laminitis. Mechanical noxious stimulation was applied to 16 loci over the solar surface of each forefoot by means of an electronic hoof tester to determine chronic pain thresholds. Horses were evaluated before and at 25, 55 and 120 min after treatment for lameness and to determine hoof compression thresholds (HCTs), the percentage of responsive loci and the subjective grade of hoof withdrawal response at each responsive locus. Detomidine produced ...
Effects of a combination of detomidine and butorphanol on respiratory function in horses with or without chronic obstructive pulmonary disease. To evaluate the effects of detomidine and butorphanol in combination on respiratory function in horses and to determine whether these effects are more severe in horses with pre-existing respiratory dysfunction, Methods: Pulmonary function testing and arterial blood gas analyses were performed before and after administration of a combination of detomidine (10 micrograms/kg of body weight, i.v.) and butorphanol (20 micrograms/kg, i.v.). Methods: 5 horses with chronic obstructive pulmonary disease and 5 horses free of respiratory disease (controls). Methods: Flow rates were obtained from a pneumo...
Simultaneous infusions of propofol and ketamine in ponies premedicated with detomidine: a pharmacokinetic study. The pharmacokinetics of propofol and ketamine administered together by infusion were investigated in four ponies. Blood propofol and plasma ketamine and norketamine concentrations were measured by high performance liquid chromatography. After premedication with detomidine (20 micrograms kg-1) anaesthesia was induced with ketamine (2.2 mg kg-1 intravenously). The trachea was intubated and the ponies were allowed to breathe 100 per cent oxygen. A bolus dose of propofol (0.5 mg kg-1) was then administered intravenously and propofol and ketamine were infused for 60 and 45 minutes, respectively. Th...
Evaluation of propofol for general anesthesia in premedicated horses. To evaluate selected hemodynamic, respiratory, and behavioral responses to propofol in horses premedicated with xylazine or detomidine. Methods: Xylazine (0.5 and 1.0 mg/kg of body weight) was administered IV on different days to each of 6 horses prior to IV administration of propofol (2 mg/kg). In a second group of 6 horses, detomidine (15 and 30 micrograms/kg) was similarly studied. Methods: 2 groups of 6 mature healthy horses. Methods: Rectal temperature, heart and respiratory rates, arterial blood gas tensions, and direct arterial blood pressures were recorded before and at fixed intervals...
Effects of sedation with detomidine hydrochloride on echocardiographic measurements of cardiac dimensions and indices of cardiac function in horses. Twenty-six horses were sedated with detomidine hydrochloride (Domosedan, SmithKline Beecham Animal Health, Tadworth, Surrey, UK) at a dose of 10 micrograms/kg bwt, administered i.v. Echocardiograms were recorded before and after sedation, measurements of cardiac dimensions were made and functional indices were calculated. The pre- and post sedation values were compared. No significant change was detected following sedation in the ejection time (ET), left ventricular dimension, left atrial diameter at the sinotubular junction at end-systole or end-diastole or at the sinus of Valsalva at end-dia...
Total intravenous anaesthesia in ponies using detomidine, ketamine and guaiphenesin: pharmacokinetics, cardiopulmonary and endocrine effects. Pharmacokinetics and some pharmacological effects of anaesthesia induced by a combination of detomidine, ketamine and guaiphenesin were investigated in eight ponies. Cardiopulmonary function was studied and plasma met-enkephalin, dynorphin, beta-endorphin, arginine vasopressin, adrenocorticotrophin, cortisol, 11-deoxycortisol and catecholamine concentrations were measured. The combination produced slight cardiorespiratory depression, hyperglycaemia and a reduction in haematocrit. There were no changes in plasma opioids, pituitary peptides or catecholamines. Plasma cortisol concentration decrea...
Sedative and analgesic effects of detomidine and romifidine in horses. In a double blind study, eight horses were treated intravenously at seven-day intervals with detomidine at doses of 10, 20 and 40 micrograms/kg, or with romifidine at doses of 40, 80 and 120 micrograms/kg, or with a placebo solution. Their sedative and analgesic effects were evaluated by objective measurements and by a clinician at 15-minute intervals for three hours and the horses' instability in stocks, locomotor ataxia and heart rate were recorded simultaneously. The administration of both drugs at all doses resulted in sedation. The sedation achieved with romifidine was significantly shall...
