Ketamine is a dissociative anesthetic commonly used in veterinary medicine for horses. It acts on the central nervous system, primarily influencing the N-methyl-D-aspartate (NMDA) receptors, leading to a trance-like state characterized by analgesia, sedation, and amnesia. In equine practice, ketamine is frequently used for induction and maintenance of anesthesia during surgical procedures, as well as for pain management. It is often administered in combination with other drugs to enhance its effectiveness and minimize side effects. This page compiles peer-reviewed research studies and scholarly articles that explore the pharmacokinetics, pharmacodynamics, and clinical applications of ketamine in equine medicine.
van Dijk P.The effects of total intravenous anaesthesia with an intravenous infusion of a combination of guaiphenesin, ketamine and detomidine were studied in 10 patients scheduled for elective surgery. Anaesthesia was maintained by the infusion of guaiphenesin (100 mg/ml), ketamine (2 mg/ml) and detomidine (0.02 mg/ml). The infusion rate was 1 ml/kg/hr. During anaesthesia, pulse rate and mean arterial blood pressure were continuously recorded. Arterial blood gases and pH were determined immediately after induction and at stated times during anaesthesia. Venous blood was sampled to determine plasma gluco...
Matthews NS, Hartsfield SM, Sanders EA, Light GS, Slater MS.All 43 horses anaesthetised for colic surgery were premedicated with xylazine or diazepam. Anaesthesia was induced with guaifenesin and ketamine, horses were placed in dorsal recumbency and anaesthesia was maintained with isoflurane in oxygen and mechanical ventilation. Haemoglobin saturation readings (SpO2) were taken with a pulse oximeter and compared with computed haemoglobin saturation (SaO2) from arterial blood samples. Readings were taken over a range of SaO2 of 78-100%, mean arterial blood pressure ranged from 24 to 108 mmHg and PaO2 ranged from 53 to 490 mmHg. Analysis of 107 readings ...
Pascoe PJ, Black WD, Steffey EP.We measured plasma concentrations of alfentanil in two horses after three different randomly ordered treatments. Each horse received halothane in oxygen by mask followed by a bolus dose of alfentanil 60 micrograms kg-1 i.v., halothane in oxygen by mask followed by an i.v. alfentanil infusion for 120 min and xylazine and ketamine followed by halothane and a bolus dose of alfentanil 60 micrograms kg-1 i.v. Halothane was maintained at 1.05-1.07% end-tidal concentration with a PaCO2 of 6-7.3 kPa. The plasma concentration-time curves were similar after bolus and infusion doses of alfentanil with ha...
Lin HC, Wallace SS, Robbins RL, Harrison IW, Thurmon JC.In 4 mares suffering from dystocia, general anesthesia was induced with xylazine (1.1 mg/kg, IV) and ketamine (2.2 mg/kg, IV) and maintained with continuous intravenous infusion of ketamine (2 mg/ml), xylazine (0.5 mg/ml) and guaifenesin (50 mg/ml) in 1 L of 5% dextrose. The duration of the procedure of these mares were 40, 45, 180, and 35 minutes, respectively. For procedures required more than 1 hour (Mare 3), the dose of ketamine and xylazine in the mixture was reduced to 1 mg/ml and 0.25 mg/ml, respectively. Average infusion rate of the mixture used to maintain anesthesia for each mare was...
Seay SS, Aucoin DP, Tyczkowska KL.A simple, rapid and sensitive high-performance liquid chromatographic procedure has been developed for the determination of ketamine and dehydronorketamine in equine serum. Sample preparation consisted of mixing equal volumes of serum and acetonitrile-phosphoric acid (85%)-water (20:2:78, v/v/v), followed by ultrafiltration through a 10,000 molecular mass cut-off filter. Separation of these two analytes in the ultrafiltrate was accomplished on a reversed-phase phenyl column eluted with methanol-acetonitrile-phosphate buffer solution. Ketamine and dehydronorketamine were detected by a variable ...
Ekström PM, Short CE, Geimer TR.This study was done to compare the electroencephalographic (EEG) response evoked by orthopedic surgery in halothane- and isoflurane-anesthetized horses. Eight horses scheduled for bilateral arthroscopic surgery of the stifle were premedicated with detomidine (20 micrograms/kg) intravenously and five minutes later induced to anesthesia with ketamine (2.2 mg/kg) intravenously. Anesthesia was maintained with either halothane or isoflurane. Assignment of inhalation anesthetic was done randomly. The multiple of minimal alveolar concentration (MAC) of halothane required for anesthesia was significan...
Matthews NS, Hartsfield SM, Sanders EA, Light GS, Walker MA.A 27-year-old horse was anesthetized 3 times a week for 4 weeks, to facilitate cobalt therapy of a squamous cell carcinoma in the left paranasal sinus. Limitations of facilities required transport of the anesthetized horse to and from the cobalt therapy room, therefore, injectable anesthesia was used. Initially, the horse was preanesthetized with xylazine (at 1.1 mg/kg IV) and butorphanol (0.04 mg/kg IV). After 3 anesthetic episodes, the xylazine dose was reduced to 0.4 mg/kg IV and the butorphanol was deleted from the regimen. Tiletamine-zolazepam (1.1 mg/kg IV) was used for induction and mai...
Diamond MJ, Young LE, Bartram DH, Gregg AS, Clutton RE, Long KJ, Jones RS.Romifidine, 100 micrograms/kg administered by intravenous injection, was evaluated as a premedicant to ketamine/halothane anaesthesia in 60 horses. Sedation developed within one to two minutes. In three cases mild staggering occurred within two minutes. Anaesthesia was induced after five minutes by the intravenous administration of ketamine (2 to 2.2 mg/kg). A mean time of 79 seconds elapsed before lateral recumbency was adopted. Fifty-four of the horses sank smoothly to the floor, with occasional steps sideways. Jaw tone, limb rigidity and mild muscle tremors often persisted for short periods...
Young LE, Bartram DH, Diamond MJ, Gregg AS, Jones RS.General anaesthesia was maintained in 40 horses by the continuous intravenous infusion of a mixture of 500 ml 10% guaifenesin solution, 1 g ketamine and 500 mg xylazine. The median duration of infusion was 65 mins (interquartile range 51-95 mins). Anaesthesia was characterised by active palpebral reflexes, variable degrees of nystagmus and occasional swallowing. Swallowing was considered to be undesirable in horses undergoing laryngeal surgery, but the infusion produced satisfactory conditions for all other surgical procedures performed. Arterial blood pressure was well maintained in all cases...
Herschl MA, Trim CM, Mahaffey EA.Twelve horses of various breeds and either sex were anesthetized with xylazine and ketamine injected into a median or lateral thoracic vein. During anesthesia, with the horse in sternal recumbency, a 14-gauge, 8.9 cm catheter was inserted into each jugular vein by using aseptic technique. Guaifenesin in water (100 mg/kg or a maximum dose of 50 grams) was infused into one jugular vein and an equal volume of 0.9% saline solution was infused into the other jugular vein. Seven horses received 10% guaifenesin, and five horses received 5% guaifenesin. The catheters were removed before the horses rec...
Muir WW, Sams R.Eight adult horses were used in a study to determine ketamine's ability to reduce halothane requirement. To obtain steady-state plasma concentrations of 0.5, 1.0, 2.0, 4.0, and 8.0 micrograms/ml, loading doses and constant infusions for ketamine were calculated for each horse on the basis of data from other studies in which the pharmacokinetic properties of ketamine were investigated. Blood samples for determination of plasma ketamine concentrations were collected periodically during each experiment. Plasma ketamine concentrations were determined by capillary gas chromatography/mass spectromet...
Taylor PM, Silver M, Fowden AL.The uterine and umbilical vessels of 12 pregnant ponies were catheterised to study foetal metabolism. The effects of this procedure on maternal and foetal cardiovascular, respiratory, metabolic and adrenocortical activity were monitored during and after surgery. Premedication with acepromazine-butorphanol-detomidine was followed by induction of anaesthesia with detomidine and ketamine and maintenance, using mechanical ventilation, with halothane in oxygen and nitrous oxide. Mean maternal arterial blood pressure was greater than 70 mmHg during anaesthesia and arterial oxygen tension remained ov...
Lester GD, Bolton JR, Cullen LK, Thurgate SM.Myoelectric activity was monitored from the terminal ileum, cecum, and colonic pelvic flexure by use of AgpAgCl bipolar electrodes in 4 adult horses before, during, and after general anesthesia. Horses were anesthetized by way of 3 commonly used regimens, including xylazine (1.1 mg/kg of body weight) and ketamine hydrochloride (2.2 mg/kg); thiopental sodium (7.7 mg/kg), followed by halothane vaporized in oxygen; and thiopental sodium (2.5 g) in guaifenesin (100 mg/ml) solution given to effect, followed by halothane in oxygen. All 3 anesthetic regimens decreased intestinal spike-burst activity ...
Luna SP, Massone F, Castro GB, Fantoni DT, Hussni CA, Aguiar AJ.A combination of 0.5 mg/kg of methotrimeprazine, 0.1 mg/kg of midazolam and 100 mg/kg of a 10 per cent guaiphenesin solution was investigated for the induction of recumbency in 15 horses; the addition of 1.6 mg/kg of ketamine was also evaluated in 15 horses and anaesthesia was maintained with halothane in oxygen. The horses became recumbent quickly and smoothly and they recovered quietly, with little ataxia. Tachycardia occurred after induction, but no other changes from pre-operative values were observed until halothane in oxygen had been given, when hypothermia, hypotension, bradypnoea, hype...
Wan PY, Trim CM, Mueller PO.Eight horses were anesthetized three times, by intravenous administration of xylazine (1.1 mg/kg) and ketamine (2.2 mg/kg), detomidine (0.02 mg/kg) and tiletamine-zolazepam (1.1 mg/kg), or detomidine (0.04 mg/kg) and tiletamine-zolazepam (1.4 mg/kg). The sequences were randomized. The duration of analgesia and the times to sternal and standing positions were recorded. Heart rate, arterial pressure, pHa, PaCO2, and PaO2 were measured before and during anesthesia. The duration of analgesia with the two doses of detomidine-tiletamine-zolazepam, 26 +/- 4 minutes and 39 +/- 11 minutes, respectively...
Matthews NS, Taylor TS, Skrobarcek CL, Williams JD.Three combinations of injectable anaesthetic agents were compared in nine adult mules. The combinations were xylazine/ketamine (X/K), xylazine/butorphanol/ketamine (X/B/K), and xylazine/tiletamine-zolazepam (X/T). Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial blood pH, PCO2 and PO2, recumbency time and number of attempts to stand. Quality of induction and recovery, muscle relaxation and response to stimulus were evaluated subjectively. Recumbency time was significantly (P < 0.05) longer with X/B/K and X/T than with X/K. Mules required significantly mor...
Matthews NS, Taylor TS, Hartsfield SM, Williams JD.Xylazine (1.1 mg/kg body weight [bwt])-ketamine (2.2 mg/kg bwt) (X/K) anaesthesia was evaluated, in nine Mammoth asses, for effectiveness and compared with two other injectable anaesthetic combinations: xylazine (1.1 mg/kg bwt)-butorphanol (0.044 mg/kg bwt)-ketamine (2.2 mg/kg bwt) (X/B/K); and xylazine (1.1 mg/kg bwt)-tiletamine-zolazepam (1.1 mg/kg bwt) (X/T). All drugs were given intravenously (i.v.). Heart rate, respiratory rate, systolic blood pressure, arterial blood pH, PCO2, PO2, recumbency time and number of attempts to stand were measured. Quality of induction and recovery, muscle re...
Lin HC, Branson KR, Thurmon JC, Benson GJ, Tranquilli WJ, Olson WA, Vähä-Vahe AT.This study was designed to assess the effects of 5 anesthetic drug combinations in ponies: (1) ketamine 2.75 mg/kg, xylazine 1.0 mg/kg (KX), (2) Telazol 1.65 mg/kg, xylazine 1.0 mg/kg (TX), (3) Telazol 2 mg/kg, detomidine 20 micrograms/kg (TD-20), (4) Telazol 2 mg/kg, detomidine 40 micrograms/kg (TD-40), (5) Telazol 3 mg/kg, detomidine 60 micrograms/kg (TD-60). All drugs were given iv with xylazine or detomidine preceding ketamine or Telazol by 5 min. Heart rate was decreased significantly from 5 min to arousal after TD-20 but only at 60 and 90 min after TD-40 and TD-60 respectively. Respirato...
Hellyer PW, Dodam JR, Light GS.Dynamic baroreflex sensitivity for increasing arterial pressure (DBSI) was used to quantitatively assess the effects of anesthesia on the heart rate/arterial pressure relationship during rapid (less than or equal to 2 minutes) pressure changes in the horse. Anesthesia was induced with IV administration of xylazine and ketamine and maintained with halothane at a constant end-tidal concentration of 1.1 to 1.2% (1.25 to 1.3 minimal alveolar concentration). Systolic arterial pressure (SAP) was increased a minimum of 30 mm of Hg in response to an IV bolus injection of phenylephrine HCl. Linear regr...
Matthews NS, Hartsfield SM, Cornick JL, Williams JD, Beasley A.Six combinations of injectable anesthetic agents were administered to six adult horses in a Latin square design. The drug combinations were xylazine-ketamine, xylazine-butorphanol-ketamine, xylazine-tiletamine-zolazepam, xylazine-butorphanol-tiletamine-zolazepam, detomidine-ketamine, and detomidine-butorphanol-ketamine. Measured variables were heart rate, respiratory rate, systolic blood pressure, arterial pH (pHa), PaCO2, PaO2, recumbency time, and number of attempts necessary to stand. Quality of induction and recovery, muscle relaxation, and response to stimulus were evaluated subjectively....
Matthews NS, Dollars NS, Young DB, Shawley RV.Short term anaesthesia induced with xylazine and ketamine was compared to a combination of xylazine, ketamine and temazepam (a benzodiazepine) in six adult horses. Duration of recumbency was significantly prolonged when temazepam was administered with xylazine and ketamine. No significant differences in heart rate, respiratory rate, blood pressure or arterial pH, pCO2 and pO2 were seen between the xylazine and ketamine combination plus temazepam, and xylazine and ketamine combination only treated horses.
McCarty JE, Trim CM, Ferguson D.On 74 occasions, 54 horses and 6 foals were anesthetized with xylazine and ketamine or xylazine, guaifenesin, and ketamine, with or without butorphanol. On 64 occasions, anesthesia was prolonged for up to 70 minutes (34 +/- 15 min) by administration of 1 to 9 supplemental IV injections of xylazine and ketamine at approximately a third the initial dosage. All horses except 5 were positioned in lateral recumbency, and oxygen was insufflated. In adult horses, the time from induction of anesthesia to the first supplemental xylazine and ketamine injection was 13 +/- 4 minutes and the time between s...
Benson GJ, Thurmon JC.Anticholinergics, tranquilizers, and sedative-hypnotics are the usual agents used for preanesthetic sedation of the horse. Of these drugs, the anticholinergics are of little importance in the horse. Acepromazine is the most useful and widely used tranquilizer, whereas xylazine is a safe and popular sedative. A newer sedative recently made available to the veterinarian for clinical use in horses is detomidine. Thiobarbiturates are seldom used alone any longer but are still useful when combined with guaifenesin for induction and maintenance of anesthesia. Other, more contemporary drug combinatio...
Brock N, Hildebrand SV.After sedation with xylazine (0.3 mg/kg intravenously [IV]), anesthesia was induced in six healthy horses with ketamine (2.0 mg/kg IV) and guaifenesin (100 mg/kg IV), diazepam (0.05 mg/kg IV), or diazepam (0.10 mg/kg IV). Anesthesia was maintained with halothane for 30 minutes. Heart rate, respiratory rate, direct arterial blood pressure, arterial blood gas, and pH measurements were made before, and at set intervals after, induction of anesthesia. Quality and characteristics of induction and recovery were evaluated objectively by an independent observer unaware of the protocol used. There were...
Schmidt-Oechtering GU, Alef M, Röcken M.Xylazine and Ketamine were used for anaesthesia in 250 adult horses. This combination is useful both for induction and maintenance of anaesthesia. The induction with Xylazine and Ketamine has been successful not only with foals but also with high risk patients such as horses with colic. During the maintenance of anaesthesia Xylazine/Ketamine can be used with injectable anaesthetics as well as with volatile anaesthetics at the same time. A form of injection anaesthesia for short-time surgical procedures like castration and wound repair is presented. The maintenance of a Thiobarbiturate/Guaifene...
Kaegi B.25 horses which entered the clinic for minor surgery, received ketamine (2.2 mg/kg i.v.) for induction of anesthesia after previous sedation with xylazine (1.1 mg/kg i.v.). As soon as the horses were in the lateral recumbency, the benzodiazepine derivate climazolam was administered at a dose of 0.1 mg/kg i.v. (10 horses) or 0.2 mg/kg i.v. (15 horses). The anesthesia was maintained with repeated injections of ketamine (1.1 mg/kg i.v. every 9-12 minutes). At the end of the surgery, 20 minutes after the last ketamine injection, Ro 15-3505, a benzodiazepine antagonist, was injected at a dose of 0....
Adams JG, Trim CM.Five horses were anaesthetised twice with thiopentone sodium, guaifenesin and halothane. The second anaesthesia was 16 days after the first and two days following oral administration of trichlorfon. Heart rate, carotid arterial, pulmonary arterial and right atrial pressures, cardiac output and blood temperature were measured every 15 minutes for 120 minutes. Heart rate, carotid arterial pressure and cardiac output were similar on both occasions. Pulmonary arterial and right atrial pressures were highest during anaesthesia after treatment with trichlorfon when compared with values obtained befo...
Trim CM, Adams JG, Cowgill LM, Ward SL.The purpose of this survey was to identify complications occurring in horses with colic during anaesthesia and recovery from anaesthesia; and to determine any relationships between these complications and drugs used for induction or maintenance of anaesthesia. Two hundred and thirty nine horses were anaesthetised on a total of 250 occasions for colic surgery between January 1985 and May 1987. Of these, 189 recovered from 200 anaesthetic episodes. Most horses received xylazine and guaifenesin with either thiobarbiturate (68 per cent) or ketamine (24 per cent) and anaesthesia was maintained with...
Schmidt-Oechtering GU.The anaesthesia with Xylazine and Ketamine in 24 foals is described. Special qualities of this form of anaesthesia and dosages for foals of different age are discussed. The combination of Xylazine and Ketamine is well suited for the anaesthesia of foals of all age and risk-groups. The induction takes place quickly and calmly, without signs of cardiorespiratory depression. The maintenance of anaesthesia is possible, without any problem, by repeated injection with Xylazine and Ketamine, as well as by inhalation anaesthesia with volatile anaesthetics. The recovery is short; the animals rise swift...
Aarnes TK, Bednarski RM, Bertone AL, Hubbell JA, Lerche P.The objective of this study was to compare recovery from desflurane anesthesia in horses with or without post-anesthetic xylazine. Six adult horses were anesthetized on 2 occasions, 14 d apart using a prospective, randomized crossover design. Horses were sedated with xylazine, induced to lateral recumbency with ketamine and diazepam, and anesthesia was maintained with desflurane. One of 2 treatments was administered intravenously at the end of anesthesia: xylazine [0.2 mg/kg body weight (BW)] or an equivalent volume of saline. Recovery parameters were recorded and assessed by 2 blinded observe...
Levionnois OL, Mevissen M, Thormann W, Spadavecchia C.The objective of this study was to assess a pharmacokinetic algorithm to predict ketamine plasma concentration and drive a target-controlled infusion (TCI) in ponies. Firstly, the algorithm was used to simulate the course of ketamine enantiomers plasma concentrations after the administration of an intravenous bolus in six ponies based on individual pharmacokinetic parameters obtained from a previous experiment. Using the same pharmacokinetic parameters, a TCI of S-ketamine was then performed over 120 min to maintain a concentration of 1 microg/mL in plasma. The actual plasma concentrations of ...
Kerr CL, Bouré LP, Pearce SG, McDonell WN.To evaluate cardiopulmonary effects of anesthetic induction with diazepam and ketamine or xylazine and ketamine, with subsequent maintenance of anesthesia with isoflurane, in foals undergoing abdominal surgery. Methods: 17 pony foals. Methods: Foals underwent laparotomy at 7 to 15 days of age and laparoscopy 7 to 10 days later. Foals were randomly assigned to receive diazepam, ketamine, and isoflurane (D/K/Iso; n = 8) or xylazine, ketamine, and isoflurane (X/K/Iso; 9) for both procedures. Results: During anesthesia for laparotomy, cardiac index, and mean arterial blood pressure ranged from 110...
Luna SP, Taylor PM, Massone F.Six Welsh gelding ponies were premedicated with 0.03 mg/kg of acepromazine intravenously (i.v.) prior to induction of anaesthesia with midazolam at 0.2 mg/kg and ketamine at 2 mg/kg i.v.. Anaesthesia was maintained for 2 h using 1.2% halothane concentration in oxygen. Heart rate, electrocardiograph (ECG), arterial blood pressure, respiratory rate, blood gases, temperature, haematocrit, plasma arginine vasopressin (AVP), dynorphin, beta-endorphin, adrenocorticotropic hormone (ACTH), cortisol, dopamine, noradrenaline, adrenaline, glucose and lactate concentrations were measured before and after ...
Matthews NS, Dollars NS, Young DB, Shawley RV.Short term anaesthesia induced with xylazine and ketamine was compared to a combination of xylazine, ketamine and temazepam (a benzodiazepine) in six adult horses. Duration of recumbency was significantly prolonged when temazepam was administered with xylazine and ketamine. No significant differences in heart rate, respiratory rate, blood pressure or arterial pH, pCO2 and pO2 were seen between the xylazine and ketamine combination plus temazepam, and xylazine and ketamine combination only treated horses.
Lin HC, Wallace SS, Robbins RL, Harrison IW, Thurmon JC.In 4 mares suffering from dystocia, general anesthesia was induced with xylazine (1.1 mg/kg, IV) and ketamine (2.2 mg/kg, IV) and maintained with continuous intravenous infusion of ketamine (2 mg/ml), xylazine (0.5 mg/ml) and guaifenesin (50 mg/ml) in 1 L of 5% dextrose. The duration of the procedure of these mares were 40, 45, 180, and 35 minutes, respectively. For procedures required more than 1 hour (Mare 3), the dose of ketamine and xylazine in the mixture was reduced to 1 mg/ml and 0.25 mg/ml, respectively. Average infusion rate of the mixture used to maintain anesthesia for each mare was...
Taylor PM, Luna SP, White KL, Bloomfield M, Fowden AL.Objective To characterize intravenous anaesthesia with detomidine, ketamine and guaiphenesin in pregnant ponies. Animals Twelve pony mares, at 260-320 days gestation undergoing abdominal surgery to implant fetal and maternal vascular catheters. Materials and methods Pre-anaesthetic medication with intravenous (IV) acepromazine (30 µg kg), butorphanol (20 µg kg) and detomidine (10 µg kg) preceded induction of anaesthesia with detomidine (10 µg kg) and ketamine (2 mg kg) IV Maternal arterial blood pressure was measured directly throughout anaesthesia and arterial blood samples were taken at ...
Caure S, Cousty M, Tricaud C.Three groups of horses scheduled for arthroscopic surgery were premedicated with 0.025 mg/kg acepromazine, 88 microg/kg romifidine and 25 mg/kg guaifenesin, and anaesthesia was induced with 2.2 mg/kg ketamine. In group 1 (14 horses), anaesthesia was maintained by halothane vaporised in oxygen, with supplementary doses of 20 microg/kg romifidine and 0.5 mg/kg ketamine every 20 minutes. The 17 horses in group 2 were maintained as for group 1; however, an additional dose of 0.05 mg/kg butorphanol was administered before the first incision. The 14 horses in group 3 were maintained as for group 2, ...
Ruíz-López P, Cuypers C, Schauvliege S.This retrospective study investigated the effect of a xylazine infusion on heart rate; mean arterial pressure; blood gases; anesthetic and dobutamine requirements; recovery quality and duration; percentage of death/survival; and days to die/discharge in horses after colic surgery under partial intravenous anesthesia with isoflurane and lidocaine infusion. Anesthetic records of equine colic surgery were reviewed from similar periods in 2020-2021 and 2021-2022. In both groups, after sedation with xylazine 0.7 mg/kg intravenously (IV) and induction with ketamine 2.2 mg/kg and midazolam 0.06 mg/kg...
Wong AM, Schier MF, Hosgood G, Drynan E, Raisis AL.To explore the influence of acepromazine on the cardiovascular effects of dobutamine in isoflurane-anaesthetised horses premedicated with romifidine. Methods: Prospective randomised clinical trial. Methods: A total of 18 horses undergoing elective arthroscopy were enrolled, of which 12 horses requiring dobutamine were included. Methods: Horses were randomised to receive acepromazine 0.02 mg kg (Group A+) intravenously (IV) or none (Group A-), 35 minutes before anaesthesia. Horses received xylazine 0.2 mg kg concurrently to facilitate IV access. Horses were premedicated with romifidine 0.08 mg ...
Lambertini C, Boanini E, Casalini I, Spaccini F, Rinnovati R, Romagnoli N.The aim of this retrospective clinical study was to compare the combinations of ketamine/diazepam (KD group) and tiletamine/zolazepam (TZ group) for the induction of general anaesthesia in horses undergoing elective surgery. The data from the clinical and the anaesthetic records of 138 horses from 2021 to 2023 were evaluated, and the horses were divided in two groups: KD ( = 60) and TZ ( = 72). The horses were premedicated with romifidine and methadone IV; anaesthesia was induced with ketamine/diazepam for the KD group and tiletamine/zolazepam for the TZ group and was maintained with isofluran...
Henderson ARP, Valverde A, Koenig J, Sears W.The objective of this prospective study was to investigate whether repeated consecutive general anesthesia in horses undergoing 2 different anesthetic protocols could lead to improved recovery scores. Six healthy female Standardbred horses (453 ± 57 kg; 6.5 ± 4.2 y old) underwent 4 anesthetic protocols over 12 to 13 wk. Procedures 1 and 4 were arthroscopic surgeries [induction: xylazine, diazepam, and ketamine; and maintenance: Fe'Isoflurane (1.1%), lidocaine (2 mg/kg body weight [BW], 50 to 100 μg/min per kg BW), dexmedetomidine (2.5 μg/h per kg BW)]. Procedures 2 and 3 were preparation f...
Kerr CL, McDonell WN, Young SS.The cardiovascular changes associated with anesthesia induced and maintained with romifidine/ketamine versus xylazine/ ketamine were compared using 6 horses in a cross over design. Anesthesia was induced and maintained with romifidine (100 microg/kg, IV)/ketamine (2.0 mg/kg, IV) and ketamine (0.1 mg/kg/min, IV), respectively, in horses assigned to the romifidine/ ketamine group. Horses assigned to the xylazine/ketamine group had anesthesia induced and maintained with xylazine (1.0 mg/kg, IV)/ketamine (2.0 mg/kg, IV) and a combination of xylazine (0.05 mg/kg/min, IV) and ketamine (0.1 mg/kg/min...
Carmalt JL, Duke-Novakovski T, Schott HC, van der Kolk JH.OBJECTIVE To determine effects of anesthesia on plasma concentrations and pulsatility of ACTH in samples obtained from the cavernous sinus and jugular vein of horses. ANIMALS 6 clinically normal adult horses. PROCEDURES Catheters were placed in a jugular vein and into the cavernous sinus via a superficial facial vein. The following morning (day 1), cavernous sinus blood samples were collected every 5 minutes for 1 hour (collection of first sample = time 0) and jugular venous blood samples were collected at 0, 30, and 60 minutes. On day 2, horses were sedated with xylazine hydrochloride and ane...
Fuentes VO.Combinations of promaxine HCl and ketamine HCl were used to produce short term dissociative anaesthesia in the horse under normal clinical conditions. Premedication with 1 mg/kg promazine HCl followed 5 min later by a rapid i.v. injection of 2 mg/kg ketamine HCl, induced dissociative anaesthesia of 16 +/- 1 min. When 1 mg/kg promazine HCl and a 2 mg/kg ketamine HCl were given simultaneously by rapid i.v. injection, a state of dissociative anaesthesia was induced with a mean duration of 17.1 +/- 2 min. Both treatments permitted minor surgery in the horse.
Mama KR, Wagner AE, Steffey EP, Kollias-Baker C, Hellyer PW, Golden AE, Brevard LF.Eight horses [5.6 ± 3.6 years, 489 ± 48.6 kg (mean ± SD)] were anesthetized four times under laboratory conditions to characterize physiologic and behavioral (reported elsewhere) responses associated with a 1-hours period of total intravenous anesthesia (TIA). Each horse was premedicated with xylazine (X, 0.75 mg kg−1) and anesthesia induced 5 minutes later with 5% guaifenesin (75 mg kg−1) and ketamine (K, 2 mg kg−1), all given IV After anesthetic induction, horses were intubated and received one of six treatments [X 35, K 90, O2; X 35, K 120, O2; X 35, K 120, air; X 35, K150, O2; X 7...
van Oostrom H, Schaap MW, van Loon JP.Hypoventilation or apnoea, caused by the induction of general anaesthesia, may cause hypoxaemia. Preoxygenation may lengthen the period before this happens. No scientific studies are published on preoxygenation in equine anaesthesia. Objective: To determine whether supplementation of oxygen at a flow rate of 15 l/min for 3 min via a nasal cannula before induction of general anaesthesia is effective in elevating the arterial partial pressure of oxygen (PaO ) directly after induction. Methods: Randomised, prospective clinical trial. Methods: A total of 18 American Society of Anesthesiologists ph...
Robertson SA.Three different anaesthetic techniques were studied in normal, healthy Thoroughbred or Thoroughbred type horses. These were (a) acepromazine, thiopentone and suxamethonium; (b) acepromazine, glyceryl guaiacolate and a 'half-dose' of thiopentone; and (c) xylazine and ketamine. Anaesthesia was maintained with halothane vaporized in oxygen and nitrous oxide. All horses underwent either laryngeal or body surface surgery. Heart rate, packed cell volume, blood glucose and lactate, plasma non-esterified fatty acids, insulin and cortisol were measured before, during and after surgery. The greatest met...
Dodman NH.Drugs and drug combinations currently in use for chemical restraint of the horse are discussed with a view to establishing their likely usefulness to the practising veterinary surgeon. Acepromazine maleate and xylazine hydrochloride are considered to be the most useful tranquillisers in spite of their limitations. A xylazine-methadone sequence is described for more profound chemical restraint and the possible future role of ketamine and glyceryl guaiacolate in combination with other agents to produce recumbency is discussed.
Schmidt-Oechtering GU.The anaesthesia with Xylazine and Ketamine in 24 foals is described. Special qualities of this form of anaesthesia and dosages for foals of different age are discussed. The combination of Xylazine and Ketamine is well suited for the anaesthesia of foals of all age and risk-groups. The induction takes place quickly and calmly, without signs of cardiorespiratory depression. The maintenance of anaesthesia is possible, without any problem, by repeated injection with Xylazine and Ketamine, as well as by inhalation anaesthesia with volatile anaesthetics. The recovery is short; the animals rise swift...
Sandbaumhüter FA, Vimercati S, Thormann W, Mevissen M.The anesthetic ketamine is often combined with analgesics and benzodiazepines in equine medicine. Therefore, drug-drug interactions are possible. Enzyme kinetics for ketamine N-demethylation were determined using equine CYP3A94, CYP3A95 and CYP3A97, and the effect of medetomidine, diazepam and methadone on the ketamine metabolism was studied in vitro. Ketamine was incubated with the CYPs or equine liver microsomes (ELM) alone or in presence of medetomidine, diazepam and/or methadone for different times. Norketamine levels were determined using enantioselective capillary electrophoresis (CE) wi...
Balko JA, Fogle C, Stuska SJ, Fogle JE, Posner LP.Butorphanol-azaperone-medetomidine (BAM™) has not been evaluated in horses. Objective: The objective of this study was to evaluate BAM™ for chemical restraint of feral horses. Methods: Retrospective and prospective descriptive studies. Methods: Data were collected retrospectively from medical records of 28 feral horses immobilised with BAM™ over a 6-year period. Prospectively, 0.0125 mL/kg bwt of BAM™ (butorphanol 27.3 mg/mL, azaperone 9.1 mg/mL and medetomidine 10.9 mg/mL) intramuscularly (im) was administered to eight stallions via dart, and once recumbent, 1.0 mg/kg bwt ketamin...
Schumacher J, DeGraves F, Cesar F, Duran S.A local anaesthetic agent capable of temporarily resolving lameness after being administered perineurally would be helpful because rapid return of lameness would allow for other analgesic techniques to be performed within a short period of time. Objective: To determine if a 3% solution of ketamine hydrochloride (HCl), administered around the palmar nerves at the level of the base of the proximal sesamoid bones, can improve naturally occurring lameness that can be improved or abolished with a basilar sesamoid nerve block performed using lidocaine HCl and to compare the change in gait produced u...
Bohner J, Painer J, Bakker D, Haw AJ, Rauch H, Greunz EM, Egner B, Goeritz F.Etorphine is widely used in zoological medicine for the immobilization of large herbivores. All reported immobilization protocols for kulans use etorphine as the primary immobilizing agent. However, etorphine can trigger severe side effects and is highly toxic for humans, its availability is occasionally limited for use in wildlife medicine. Therefore, two different alpha-2 agonist-based protocols for the general anesthesia of kulans were investigated and compared with the standard etorphine immobilization. In total, 21 immobilizations were performed within the scope of routine husbandry manag...
Wilkens HL, Neudeck S, Kästner SBR.The present study aimed to investigate the effect of endotracheal intubation on nasal and tracheal endogenous NO concentrations, gas exchange and oxygenation in horses undergoing general anaesthesia. In many species a major part of physiological nitric oxide (NO) production takes place in the nasopharynx. Inhaled NO acts as a pulmonary vasodilator and regulates lung perfusion and endotracheal intubation bypasses the nasopharynx. Six horses were randomly assigned to either the "intubated" (INT) or the "non-intubated" (nINT) treatment group. Horses were premedicated with dexmedetomidine (5 μg...
Cunneen A, Pratt S, Perkins N, McEwen M, Truchetti G, Rainger J, Farry T, Kidd L, Goodwin W.To evaluate the use of ketamine-medetomidine-midazolam total intravenous infusion as part of a balanced anaesthetic technique for surgical castration in horses. Five healthy Standardbred cross colts were premedicated with IV acepromazine (0.01-0.02 mg/kg), medetomidine (7 µg/kg) and methadone (0.1 mg/kg) and anaesthesia induced with IV ketamine (2.2 mg/kg) and midazolam (0.06 mg/kg). Horses were anaesthetised for 40 min with an IV infusion of ketamine (3 mg/kg/h), medetomidine (5 µg/kg/h) and midazolam (0.1 mg/kg/h) while routine surgical castration was performed. Cardiorespiratory variables...
Marlin DJ, Young LE, McMurphy R, Walsh K, Dixon P.There is evidence that halothane inhibits nitric oxide synthase in vitro, but the effect of intravenous anaesthetic agents is less clear. This study was undertaken to compare the rate of exhaled nitric oxide production (VNO) in spontaneously breathing horses anaesthetized with halothane or an intravenous regimen. Seven adult horses were studied twice in random order. After premedication with romifidine 100 microg kg(-1), anaesthesia was induced with ketamine 2.2 mg kg(-1) and maintained with halothane in oxygen (HA) or by an intravenous infusion of ketamine, guaiphenesin and romifidine (IV). I...
