Chemical restraint of fishers (Martes pennanti) with ketamine and medetomidine-ketamine.

We chemically restrained fishers (Martes pennanti) as part of a captive-management protocol designed to facilitate veterinary evaluation and treatment, and conditioning on a high-calorie diet before reintroduction in Pennsylvania. We compared the safety and efficacy of ketamine (KET) and medetomidine-ketamine (MED-KET) by monitoring immobilization intervals (induction time, down time, alert time, and recovery time) and physiologic responses (pulse rate, respiration rate, rectal temperature, blood pressure, oxygen saturation, and mean arterial pressure) during restraint. We administered MED-KET at 0.4 mg MED combined with 20.0 mg KET to males and at 0.2 mg MED combined with 10.0 mg KET to females. The x +/- SD dosages were MED 0.07 +/- 0.008 mg/kg + KET 3.7 +/- 0.5 mg/ kg for males and MED 0.07 +/- 0.007 mg/kg + KET 3.6 +/- 0.3 mg/kg for females. KET alone was administered at 100.0 mg to males and at 50.0 mg to females. resulting in x +/- SD dosages of 18.7 +/- 1.8 mg/kg for males and 19.2 +/- 2.2 mg/kg for females. Mean induction time did not differ between fishers restrained with MED-KET (4.6 min) and KET (4.5 min). However, compared with KET, MED-KET resulted in longer mean down time (36.2 vs. 142.2 min), alert time (40.8 vs. 146.8). and recovery time (81.1 vs. 199.4 min). Fishers that received MED-KET were mildly bradycardic and hypertensive compared with those that received KET. Although KET resulted in increased muscle tension and labored respiration, it would be effective for performing brief, noninvasive procedures for fishers because induction was rapid, recovery was short and calm, anesthesia was not profound, and physiologic response was generally expected on the basis of known drug pharmacology. Medetomidine-ketamine also immobilized fishers effectively, providing rapid induction, physiologic response typical to alpha2 agonism, calm recovery, and possibly a plane of anesthesia adequate for invasive procedures such as tooth removal or surgery.     

Use of medetomidine and ketamine for immobilization of free-ranging giraffes

OBJECTIVE: To develop a dosage correlated with shoulder height (SH) in centimeters for effective immobilization of free-ranging giraffes, using a combination of medetomidine (MED) and ketamine (KET) and reversal with atipamezole (ATP). DESIGN: Prospective study. ANIMALS: 23 free-ranging giraffes. PROCEDURE: The drug combination (MED and KET) was administered by use of a projectile dart. Quality of induction, quality of immobilization, and time to recovery following injection of ATP were evaluated. Physiologic variables measured during immobilization included PaO2, PaCO2, oxygen saturation, end-tidal CO2, blood pH, indirect arterial blood pressure, heart and respiratory rates, and rectal temperature. RESULTS: Sixteen giraffes became recumbent with a dosage (mean +/- SD) of 143 +/- 29 microg of MED and 2.7 +/- 0.6 mg of KET/cm of SH. Initially, giraffes were atactic and progressed to lateral recumbency. Three giraffes required casting with ropes for data collection, with dosages of 166 +/- 5 microg of MED and 3.2 +/- 0.6 mg of KET/cm of SH. Four giraffes required administration of etorphine (n = 2) or were cast with ropes (2) for capture but remained dangerous to personnel once recumbent, precluding data collection. In giraffes successfully immobilized, physiologic monitoring revealed hypoxia and increased respiratory rates. Values for PaCO2, end-tidal CO2, and heart rate remained within reference ranges. All giraffes were hypertensive and had a slight increase in rectal temperature. Atipamezole was administered at 340 +/- 20 microg/cm of SH, resulting in rapid and smooth recoveries. CONCLUSIONS AND CLINICAL RELEVANCE: Medetomidine and KET was an effective immobilizing combination for free-ranging giraffes; however, at the dosages used, it does not induce adequate analgesia for major manipulative procedures. Quality of induction and immobilization were enhanced if the giraffe was calm. Reversal was rapid and complete following injection of ATP.     

Clinical evaluation of established optimal immobilizing doses of medetomidine-ketamine in captive reindeer (Rangifer tarandus tarandus)

OBJECTIVE: To evaluate clinical effects and repeatability of clinical effects for an optimal immobilizing dose of a combination of medetomidine hydrochloride (MED) and ketamine hydrochloride (KET) in reindeer (Rangifer tarandus tarandus). ANIMALS: 12 healthy 6- to 8-month old reindeer. PROCEDURE: Each reindeer was immobilized once with an initial dose (combination of 0.06 mg of MED/kg of body weight and 0.3 mg KET/kg) and twice with an optimal dose of MED-KET. Reversal was achieved with 5 mg of atipamezole/mg of MED injected 45 minutes after MED-KET administration. Observational variables were recorded. Oxygen saturation of arterial hemoglobin measured by pulse oximetry (Spo2), respiratory rate (RR), heart rate (HR), and rectal temperature (RT) were recorded 10, 25, and 40 minutes after immobilization. RESULTS: Mean time to first sign of sedation and time until a recumbent animal lifted its head were significantly reduced for reindeer given the optimal dose, compared with the initial dose. Mean Spo2 remained > 90% during initial immobilization; this value was significantly lower for the optimal dose, but increased during immobilization from 85 to 89%. At all doses, RR increased significantly throughout the recorded period; however, RT and HR were constant. Except for time until reindeer stood, all time variables, Spo2, RR, RT, and HR were repeatable. CONCLUSION AND CLINICAL RELEVANCE: mmobilization of captive reindeer achieved by use of the optimal dose established here is clinically acceptable, although Spo2 should be carefully monitored. Administration of the optimal dose produced the same clinical effect during repeated immobilization of the same reindeer.     

Determination of optimal immobilizing doses of a medetomidine hydrochloride and ketamine hydrochloride combination in captive reindeer

OBJECTIVE: To establish optimal immobilizing doses of medetomidine hydrochloride (MED) with ketamine hydrochloride (KET) for hand- and dart-administered injections in captive reindeer. ANIMALS: 12 healthy 6- to 9-month-old reindeer (Rangifer tarandus tarandus). Procedure An optimal dose was defined as a dose resulting in an induction time of 150 to 210 seconds, measured from the time of IM injection until recumbency. Initially, each stalled reindeer was immobilized by hand-administered injection. If the induction time was > 210 seconds, the dose was doubled for the next immobilization procedure. If it was < 150 seconds, the dose was halved for the next immobilization procedure. This iteration procedure was continued for each reindeer until an optimal dose was found. Later the reindeer was placed in a paddock and darted with its optimal dose as determined by hand-administered injection. Adjusting to a linear relationship between dose and induction time, optimal darting doses for each reindeer were predicted and later verified. RESULTS: The established mean optimal hand- and dart-administered doses were 0.10 mg of MED/kg of body mass with 0.50 mg of KET/kg, and 0.15 mg of MED/kg with 0.75 mg of KET/kg, producing mean induction times of 171 seconds and 215 seconds, respectively. The mean induction time after darting was 5 seconds greater than the upper limit of the predefined time interval. CONCLUSIONS AND CLINICAL RELEVANCE: The higher dose requirement of MED-KET administration outdoors, compared with indoors, was explained by factors inherent in the darting technique and the different confinements. The iteration and the prediction methods seem applicable for determination of optimal doses of MED-KET in reindeer. The iteration and the prediction procedures may be used to reduce the number of experimental animals in dose-response studies in other species.     

Xylazine-induced sedation in axis deer (Axis axis) and its reversal by atipamezole

Eight free-ranging axis deer (Axis axis) were captured in drive nets and injected with xylazine (3.4±0.1 mg/kg; mean ±SEM) intramuscularly using a hand-held syringe. Xylazine induced complete immobilization and sedation in three animals, heavy sedation in three, and moderate sedation in two. The mean induction time was 10.4±1.0 min. The mean rectal temperature, heart and respiratory rates of immobilized animals were 39.2±0.4°C, 75.5±6.5 beats/min and 62.1±4.2 breaths/min, respectively.All the animals were given atipamezole intravenously for reversal. The mean time from injection of xylazine to administration of atipamezole was 37.8±4.6 min. A dose ratio (w/w) for xylazine:atipamezole-HCl of 10:1 was used. The mean time from injection of atipamezole to mobility was 2.41±0.58 min.Atipamezole given intravenously effectively antagonized xylazine-induced sedation in axis deer. Only one animal showed signs of overalertness after reversal and no cases of resedation were observed.Abbreviations i.m. intramuscular(ly) - i.v. intravenous(ly) - SEM standard error of the mean     

Serial temperature monitoring and comparison of rectal and muscle temperatures in immobilized free-ranging black rhinoceros (Diceros bicornis)

Control of body temperature is critical to a successful anesthetic outcome, particularly during field immobilization of wild animals. Hyperthermia associated with exertion can lead to serious and potentially life-threatening complications such as organ damage (including myopathy) and death. Methods for monitoring core body temperature must accurately reflect the physiologic status of the animal in order for interventions to be effective. The goal of this preliminary study was to compare serial rectal and muscle temperatures in field-immobilized black rhinoceros (Diceros bicornis) and evaluate a possible association. Twenty-four free-ranging black rhinoceros were immobilized between February and March of 2010 in Ethosha National Park, Namibia. Pairwise comparisons showed a correlation of 0.73 (95% CI; 0.70-0.75) between rectal and muscle temperature measurements. Results from a multivariable model indicate that muscle temperature readings were, on average, 0.46 degrees C (95% CI; 0.36-0.57 degrees C) higher than rectal temperatures while adjusting for repeated measurements on the same rhinoceros, effect of duration of immobilization, and effect of ambient temperature on rhinoceroses' temperature readings. As immobilization time increased, muscle and rectal temperature values within an individual rhinoceros tended to equilibrate. The overall temperatures decreased by an average of 0.00059 degrees C/min (95% CI; -0.0047 to -0.0035 degrees C/min; P = 0.779). As the ambient temperature at time of immobilization increased by 1 degree C, the average rhinoceros temperature increased by 0.09 degrees C (95% CI; 0.06-0.11 degrees C, P < 0.0001). Higher body temperature creates a potential for cellular damage leading to complications that include myopathy. Methods for monitoring rectal, muscle, and ambient temperatures should be incorporated into anesthetic monitoring protocols for large ungulates, particularly under field conditions.     

Reversal of xylazine-induced sedation in dairy calves with atipamezole: A field trial

Dairy calves immobilized with xylazine (XYL) were given atipamezole-HCl (ATI) at different XYL:ATI dose ratios (w/w) for reversal and the antagonistic effect of xylazine was evaluated. Control animals received saline for comparison. Intramuscular administration of xylazine (0.139–0.357 mg/kg) induced sedation with complete immobilization in all animals (n=195) and there were no spontaneous recoveries before injection of atipamezole or saline. Atipamezole was given 10–81 min and saline 25 min after xylazine administration. Intramuscular administration of atipamezole at XYL:ATI dose ratios of 5:2 (n=11), 10:3 (n=21), 4:1 (n=21) and 5:1 (n=25) effectively antagonized the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 6.09 (3.12), 5.15 (2.87), 6.35 (2.54) and 7.86 (3.11) min, respectively. The mean time to standing for control animals (n=11) was 94.1 (3.0) min. Intravenous administration of atipamezole at XYL:ATI dose ratios of 10:3 (n=7), 4:1 (n=33), 5:1 (n=16), 8:1 (n=27) and 10:1 (n=9) rapidly reversed the xylazine-induced immobilization and sedation. The mean times (standard deviation) from injection of atipamezole until the animals were standing for these dose ratio groups were 0.98 (0.22), 1.32 (0.48), 1.09 (0.34), 1.39 (0.52) and 1.60 (0.69) min, respectively. The mean time to standing for control animals (n=14) was 88.1 (13.1) min.Animals given high doses of atipamezole (dose ratio groups 5:2 intramuscularly, 10:3 intravenously and 4:1 intravenously) showed signs of excitement while in animals given low doses of atipamezole (dose ratio groups 5:1 intramuscularly and 10:1 intravenously) resedation and relapse into recumbency occurred. Medium doses of atipamezole (dose ratio groups 10:3 intramuscularly, 4:1 intramuscularly, 5:1 intravenously and 8:1 intravenously) did not cause any undesirable side-effects or resedation, and can be recommended for reversal of xylazine-induced sedation in dairy calvesAbbreviations ATI atipamezole-HCl - BW body weight - IM intramuscular - IV intravenous - SD standard deviation - XYL xylazine     

Antagonistic effects of atipamezole, flumazenil and 4-aminopyridine against anaesthesia with medetomidine, midazolam and ketamine combination in cats

Antagonistic effects of atipamezole (ATI), flumazenil (FLU) and 4-aminopyridine (4AP) alone and in various combinations after administration of medetomidine-midazolam-ketamine (MED-MID-KET) were evaluated in cats. Animals were anaesthetised with MED (50 microg/kg), MID (0.5 mg/kg) and KET (10 mg/kg) given intramuscularly. Twenty minutes later, physiological saline, ATI (200 microg/kg), FLU (0.1 mg/kg), 4AP (0.5 mg/kg), ATI-FLU, FLU-4AP, ATI-4AP or ATI-FLU-4AP was administered intravenously. FLU, 4AP alone, or FLU-4AP did not effectively antagonise the anaesthesia, hypothermia, bradycardia, and bradypnoea induced by MED-MID-KET. ATI alone was effective. ATI-FLU, ATI-4AP and ATI-FLU-4AP combinations produced an immediate and effective recovery from anaesthesia. The combination of ATI-FLU-4AP was the most effective in antagonising the anaesthetic effects, but was associated with tachycardia, tachypnoea, excitement, and muscle tremors. Combinations with ATI are more effective for antagonising anaesthesia, but ATI-FLU-4AP is not suitable.     

Evaluation of the anaesthetic effects of medetomidine and ketamine in rats and their reversal with atipamezole

ObjectivesTo compare the anaesthetic effects of varying doses of medetomidine (MED) combined with ketamine (KET) in rats, and to determine the efficacy of atipamezole (ATI) in the reversal of these effects using electroencephalogram (EEG) and assessment of clinical parameters.Study designProspective, randomized experimental trial.AnimalsTwenty-one male Sprague–Dawley rats weighing 300–398 g and aged 8–11 weeks old.MethodsThree groups received intraperitoneal injections of MED (0.2, 0.4 or 0.8 mg kg^?1) with KET (60 mg kg^?1) (MED-200, MED-400 and MED-800). Atipamezole, at doses five times higher than the previous dose of MED, was then administered intraperitoneally 70 minutes after MED-KET injection. The EEG band powers and spectral edge frequencies (SEFs), respiratory rates, reflex scores to toe-web clamping and behavioural changes were measured. Correlations between EEG parameters and reflex scores were also evaluated.ResultsThe duration of surgical anaesthesia was directly proportional to the dose of MED. Lower frequency bands (δ1 to α2) increased in all groups, and these changes were reversed by ATI. Minimal changes were observed in the higher frequency bands (β1 to γ), but their powers were increased by ATI. The SEFs were decreased in all groups, and they were reversed by ATI. While α1 band power and SEF95 showed strong correlations with the depth of anaesthesia, their changes appeared before the measured decreases in reflex score. Recovery from anaesthesia was extended by increasing the dose of MED.Conclusions and clinical relevanceSpectral EEG parameters may not accurately predict the depth of surgical anaesthesia because they had already changed during the induction of surgical anaesthesia. The ATI dose used in the present study may not be enough for complete reversal of anaesthesia induced by MED-KET.     

Evaluation of the clinical efficacy and safety of dexmedetomidine or medetomidine in cats and their reversal with atipamezole

OBJECTIVE: To evaluate and compare the clinical effects of dexmedetomidine (DEX) and medetomidine (MED) in cats, and their reversal with atipamezole (ATI). Study design Prospective blinded randomized multi-centre clinical trial. Animals One hundred and twenty client-owned cats. METHODS: Cats were randomly allocated to receive a single intramuscular (IM) injection of either DEX (0.04 mg kg(-1), n = 62) or MED (0.08 mg kg(-1), n = 58) for minor procedures requiring sedation and analgesia. Afterwards, ATI (0.2 mg kg(-1)) was administered IM to half the cats, randomly assigned. Prior to, during and after the procedure the sedative, analgesic and cardiorespiratory effects and body temperature were assessed. RESULTS: Dexmedetomidine and MED produced clinically and statistically comparable effects. The intended procedure(s) could be performed in over 90% of cats. Sedation and analgesia were apparent within 5 minutes, peak effects were observed at approximately 30 minutes and spontaneous recovery occurred by 180 minutes of injection. Heart and respiratory rate and body temperature decreased significantly over time and had not returned to baseline values 180 minutes after administration. ATI administration completely reversed the sedative and analgesic effects, returned the heart rate to normal and prevented any further reductions in respiratory rate and body temperature in both DEX- and MED-treated cats. The reporting of adverse events was low and the most commonly observed event was vomiting (7%). No serious adverse events or concerns regarding safety were reported. CONCLUSIONS AND CLINICAL RELEVANCE: Dexmedetomidine (0.04 mg kg(-1)) produced comparable sedative and analgesic effects to MED (0.08 mg kg(-1)) in cats. DEX produced adequate sedation and analgesia for radiography, grooming, dental care and lancing of abscesses. ATI fully reversed the clinical effects of DEX.     

Pharmacokinetics and pharmacodynamics of carfentanil and naltrexone in female common eland (Taurotragus oryx).

The pharmacokinetic parameters of carfentanil and naltrexone were determined in the common eland (Taurotragus oryx). Six adult females were immobilized with xylazine (0.23 +/- 0.03 mg/kg i.m.) and carfentanil (0.0169 +/- 0.0005 mg/kg i.m.) for a 45-min period, during which time routine health care procedures were performed. Heart and respiration rates and body temperatures were monitored throughout the immobilization period. A single intramuscular injection of naltrexone (1.66 +/- 0.08 mg/kg i.m.) was sufficient for reversal. The eland were intermittently restrained in a hydraulic squeeze chute for serial blood sample collection via jugular venipuncture during immobilization and up to 48 hr post-immobilization. The quantification of carfentanil and naltrexone in the plasma was performed by liquid chromatography and mass spectroscopy methods. Carfentanil was rapidly absorbed following administration, with the peak plasma concentration (C(max)) at 13.8 min. Naltrexone was readily absorbed and reached C(max) at 23.4 +/- 16.8 min after administration. All animals stood 2.7 +/- 2.2 min after naltrexone administration. Carfentanil has a half-life of 7.7 hr, whereas naltrexone has a much shorter half-life of 3.7 hr. Although respiratory rates appeared to fluctuate widely among animals, heart rates and body temperature remained stable throughout the immobilization. Renarcotization was not noted as a major complication.     

Anaesthesia of nyala (Tragelaphus angasi) with a combination of thiafentanil (A3080), medetomidine and ketamine

A combination of thiafentanil (A3080), medetomidine hydrochloride (MED) and ketamine hydrochloride (KET) was evaluated in 19 boma-habituated (12 female and 7 males) and 9 free-ranging nyala (7 male and 2 females) (Tragelaphus angasi) to develop a safe and reliable anaesthesia protocol. Wide dosages were used safely during this study with ranges for A3080 of 45 +/- 8 microg/kg with MED of 69 +/- 19 microg/kg and KET of 3.7 +/- 1.0 mg/kg (200 mg/ animal). The dosages developed on boma-habituated nyala proved to be equally effective in 9 adult free-ranging nyala (7 males and 2 females). The optimum dosage for nyala was a combination of A3080 (40-50 microg/kg), MED (60-80 microg/kg) plus 200 mg of KET/animal. The anaesthesia was characterised by a short induction, good muscle relaxation and mild hypoxaemia during monitoring the anaesthesia was rapidly and completely reversed by naltrexone hydrochloride (30 mg/mg of A3080) and atipamezole hydrochloride (5 mg/mg of MED) given intramuscularly. There was no mortality or morbidity associated with this protocol.     

Antagonistic effect of atipamezole, flumazenil and naloxone following anaesthesia with xylazine, tramadol and tiletamine/zolazepam combinations in pigs

ObjectiveTo evaluate the antagonistic effects of atipamezole (ATI), flumazenil (FLU) and naloxone (NAL) alone and in various combinations following administration of tiletamine–zolazepam–xylazine–tramadol.Study designProspective, experimental, randomized cross-over study.AnimalsEight Chinese miniature pigs (three females and five males) mean age 8 (range 7–10) months and bodyweight 57.5 (52.4–62.1) kg.MethodsAll animals were anaesthetized with tiletamine/zolazepam (3.0 mg kg^?1), xylazine (1.2 mg kg^?1) and tramadol (1.6 mg kg^?1) given intramuscularly (IM). Thirty minutes later, one of eight treatments was administered IM: saline control, ATI (0.12 mg kg^?1), FLU (0.1 mg kg^?1), NAL (0.03 mg kg^?1), ATI–FLU, FLU–NAL, ATI–NAL or ATI–FLU–NAL. After injection of antagonists the following times were recorded: to recovery of the palpebral, pedal and tail clamp reflexes, to head movement, sternal recumbency, standing and walking. Posture, sedation, analgesia, jaw relaxation and auditory response were scored at set times until 120 minutes after injection of antagonists. Heart rates, respiratory rates and rectal temperature were measured at those times. Data were analyzed by anova for repeated measures, followed by the Tukey’s test to compare differences between means, or by Kruskal–Wallis test as appropriate.ResultsFLU, NAL alone, or FLU–NAL did not effectively antagonize anaesthesia induced by tiletamine/zolazepam–xylazine–tramadol. ATI, ATI–FLU, ATI–NAL and ATI–FLU–NAL produced an immediate and effective recovery from anaesthesia. The combination of ATI–FLU–NAL was the most effective combination in antagonizing the anaesthetic effect. Adverse effects such as tachycardia, tachypnoea, excitement and muscle tremors were not observed during this study.Conclusion and clinical relevanceATI–FLU–NAL is the most effective combination for antagonizing tiletamine/zolazepam–xylazine–tramadol anaesthesia in pigs. However, ATI alone or in various combinations also provides effective antagonism.     

Effects of ketamine, diazepam, and their combination on intraocular pressures in clinically normal dogs

OBJECTIVE: To evaluate the effects of ketamine, diazepam, and the combination of ketamine and diazepam on intraocular pressures (IOPs) in clinically normal dogs in which premedication was not administered. ANIMALS: 50 dogs. PROCEDURES: Dogs were randomly allocated to 1 of 5 groups. Dogs received ketamine alone (5 mg/kg [KET5] or 10 mg/kg [KET10], IV), ketamine (10 mg/kg) with diazepam (0.5 mg/kg, IV; KETVAL), diazepam alone (0.5 mg/kg, IV; VAL), or saline (0.9% NaCl) solution (0.1 mL/kg, IV; SAL). Intraocular pressures were measured immediately before and after injection and at 5, 10, 15, and 20 minutes after injection. RESULTS: IOP was increased over baseline values immediately after injection and at 5 and 10 minutes in the KET5 group and immediately after injection in the KETVAL group. Compared with the SAL group, the mean change in IOP was greater immediately after injection and at 5 and 10 minutes in the KET5 group. The mean IOP increased to 5.7, 3.2, 3.1, 0.8, and 0.8 mm Hg over mean baseline values in the KET5, KET10, KETVAL, SAL, and VAL groups, respectively. All dogs in the KET5 and most dogs in the KETVAL and KET10 groups had an overall increase in IOP over baseline values. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with baseline values and values obtained from dogs in the SAL group, ketamine administered at a dose of 5 mg/kg, IV, caused a significant and clinically important increase in IOP in dogs in which premedication was not administered. Ketamine should not be used in dogs with corneal trauma or glaucoma or in those undergoing intraocular surgery.     

The impact of MK‐467 on plasma drug concentrations,sedation and cardiopulmonary changes in sheep treated with intramuscular medetomidine and atipamezole for reversal

The effect of MK‐467, a peripheral α₂‐adrenoceptor antagonist, on plasma drug concentrations, sedation and cardiopulmonary changes induced by intramuscular (IM) medetomidine was investigated in eight sheep. Additionally, the interactions with atipamezole (ATI) used for reversal were also evaluated. Each animal was treated four times in a randomized prospective crossover design with 2‐week washout periods. Medetomidine (MED) 30 μg/kg alone or combined in the same syringe with MK‐467 300 μg/kg (MMK) was injected intramuscular, followed by ATI 150 μg/kg (MED + ATI and MMK + ATI) or saline intramuscular 30 min later. Plasma was analysed for drug concentrations, and sedation was subjectively assessed with a visual analogue scale. Systemic haemodynamics and blood gases were measured before treatments and at intervals thereafter. With MK‐467, medetomidine plasma concentrations were threefold higher prior to ATI, which was associated with more profound sedation and shorter onset. No significant differences were observed in early cardiopulmonary changes between treatments. Atipamezole reversed the medetomidine‐related cardiopulmonary changes after both treatments. Sedation scores decreased more rapidly when MK‐467 was included. In this study, MK‐467 appeared to have a pronounced effect on the plasma concentration and central effects of medetomidine, with minor cardiopulmonary improvement.     

Cardiopulmonary and anesthetic effects of medetomidine-ketamine-butorphanol and antagonism with atipamezole in servals (Felis serval).

Seven (three male and four female) 4-7-yr old captive servals (Felis serval) weighing 13.7 +/- 2.3 kg were used to evaluate the cardiopulmonary and anesthetic effects of combined intramuscular injections of medetomidine (47.4 +/- 10.3 microg/kg), ketamine (1.0 +/- 0.2 mg/kg), and butorphanol (0.2 +/- 0.03 mg/kg). Inductions were smooth and rapid (11.7 +/- 4.3 min) and resulted in good muscle relaxation. Significant decreases in heart rate (85 +/- 12 beats/min) at 10 min after injection and respiratory rate (27 +/- 10 breaths/min) at 5 min after injection continued throughout the immobilization period. Rectal temperature and arterial blood pressure did not change significantly. The PaO2 decreased significantly, and PaCO2 increased significantly during immobilization but remained within clinically acceptable limits. Hypoxemia (PaO2 < 60 mm Hg) was not noted, and arterial blood oxygen saturation (SaO2) was greater than 90% at all times. Relative arterial oxygen saturation (SpO2) values, indicated by pulse oximetry, were lower than SaO2 values. All animals could be safely handled while sedated. Administration of atipamezole (236.8 +/- 51.2 microg/kg half i.v. and half s.c.), an alpha2 antagonist, resulted in rapid (4.1 +/- 3 min to standing) and smooth recoveries.     

Comparative cardiopulmonary effects of carfentanil-xylazine and medetomidine-ketamine used for immobilization of mule deer and mule deer/white-tailed deer hybrids.

Three mule deer and 4 mule deer/white-tailed deer hybrids were immobilized in a crossover study with carfentanil (10 microg/kg) + xylazine (0.3 mg/kg) (CX), and medetomidine (100 microg/kg) + ketamine (2.5 mg/kg) (MK). The deer were maintained in left lateral recumbency for 1 h with each combination. Deer were immobilized with MK in 230+/-68 s (mean +/- SD) and with CX in 282+/-83 seconds. Systolic, mean and diastolic arterial pressure were significantly higher with MK. Heart rate, PaO2, PaCO2, pH, and base excess were not significantly different between treatments. Base excess and pH increased significantly over time with both treatments. Both treatments produced hypoventilation (PaCO2 > 50 mm Hg) and hypoxemia (PaO2 < 60 mm Hg). PaO2 increased significantly over time with CX. Body temperature was significantly (P<0.05) higher with CX compared to MK. Ventricular premature contractions, atrial premature contractions, and a junctional escape rhythm were noted during CX immobilization. No arrhythmias were noted during MK immobilization. Quality of immobilization was superior with MK, with no observed movement present for the 60 min of immobilization. Movement of the head and limbs occurred in 4 animals immobilized with CX. The major complication observed with both of these treatments was hypoxemia, and supplemental inspired oxygen is recommended during immobilization. Hyperthermia can further complicate immobilization with CX, reinforcing the need for supplemental oxygen.     

The use of a medetomidine, butorphanol and atropine combination to enable blood sampling in young pigs

AIM: To determine the suitability of a reversible, injectable anaesthetic combination including medetomidine, butorphanol and atropine to produce the degree of immobilisation required to allow blood sampling in young pigs. METHODS: Twenty 6-week-old crossbred, intact male pigs were sedated with an intramuscular (I/M) injection of 80 microg/kg medetomidine, 200 microg/kg butorphanol and 25 microg/kg atropine. Heart and respiratory rates and rectal temperatures were monitored. Excessive salivation, gagging, laryngeal reflex, presence of pedal reflex and deep and surface analgesia were noted. Time of injection and the time when pigs reached mild and full sedation were also recorded. RESULTS: Mild sedation was produced in 90% of pigs after 5.6 (SEM 0.96) min (n = 18; median 5, range 2-16 min), and full sedation (lateral recumbency and loss of jaw tone) in 60% of pigs after 12.5 (SEM 2.14) min (n = 12; median 10, range 5-28 min). The depth and duration of sedation were very variable and most animals were easily aroused. Ninety percent of the animals required the administration of halothane by mask to allow blood sampling, but the amount of halothane required was small. Heart and respiratory rates decreased (p < 0.001) but remained within the normal range. Rectal temperature was above normal at the time of sedation and at the time of blood sampling when the ambient temperature was 29 degrees C but not when the ambient temperature was reduced to 25 degrees C. CONCLUSIONS: The combination of medetomidine, butorphanol and atropine at these doses produced sedation of variable depth and duration that was insufficient on its own to allow blood sampling in the majority of pigs. Hyperthermia can occur in temperature-controlled environments when using medetomidine, butorphanol and atropine in pigs. Reduction of stress and a quieter environment may improve the effects of the anaesthetic combination.     

Preliminary studies of alfaxalone for intravenous immobilization of juvenile captive estuarine crocodiles (Crocodylus porosus) and Australian freshwater crocodiles (Crocodylus johnstoni) at optimal and selected sub‐optimal thermal zones

ObjectivesTo investigate the character of immobilization given by alfaxalone in juvenile crocodiles at optimal and at suboptimal temperatures.Study designProspective, randomized partial crossover study.AnimalsTwenty captive male estuarine (weight 0.6–2.5 kg) and five captive male freshwater crocodiles (weight 0.2–0.6 kg).MethodsCrocodiles were acclimatized for 24 hours at one of the following environmental temperatures; 32 °C, 27 °C, 22 °C or 17 °C, then received 3 mg kg^?1 intravenous (IV) alfaxalone into the dorsal occipital venous sinus. Duration and quality of immobilization was assessed and heart rate (HR) measured. On a separate occasion each crocodile was immobilized at one other environmental temperature.ResultsAlfaxalone, 3 mg kg^?1 IV, produced immobilization for 55 (range 15–100 minutes in estuarine, and 20 (range 20–25) minutes in freshwater crocodiles at 32 °C. There was no significant difference overall in immobilization times between temperatures, other than that, in estuarine crocodiles, duration was shorter at 32 °C than 22 °C. The character of immobilization was unpredictable, with animals recovering without warning, or having extended recoveries requiring assisted ventilation. Assisted ventilation was necessary mainly at the lower temperatures. Median HR in all temperature treatments decreased within 5 minutes post–injection, but the change in HR over the duration of immobilization was affected by the temperature, with a progressively smaller range of fall as temperature decreased. At 17 °C, two estuarine crocodiles appeared to re–immobilize after initial recovery, became severely bradycardiac and required ventilation and re–warming.Conclusions and clinical relevanceAlfaxalone IV in small captive estuarine and freshwater crocodiles provides adequate induction of immobilization at various temperatures. However, the unpredictable results following induction mean it is unsuitable for field use and should be restricted to environments where intubation and ventilation are available, where animals can be warmed to optimal temperature, and where access to immersion in water can be restricted for 24 hours.     

Comparison of three doses of dexmedetomidine with medetomidine in cats following intramuscular administration

Cats ( n  = 6) were administered dexmedetomidine (DEX) and medetomidine (MED) at three different dose levels in a randomized, blinded, cross-over study. DEX was administered at 25, 50 and 75 μg/kg (D25, D50 and D75), corresponding to MED 50, 100 and 150 μg/kg (M50, M100 and M150). Sedation, analgesia and muscular relaxation were scored subjectively. Heart and respiratory rates and rectal temperature were measured. Corresponding doses of DEX and MED were compared. Effects were also compared between dose levels for each compound. At dose level 2 (D50-M100), the duration of effective clinical sedation was significantly shorter after DEX (202.5±16.0 min) than after MED (230.0±41.2 min). Proceeding from D50-M100 to D75-M150, the duration of effective clinical sedation was increased more after DEX (by 57.5±38.4 min) than after MED (by 14.2±41.9 min) Increasing from D50-M100 to D75-M150, heart rate was further decreased after DEX (by 8.1±13.4%) but not after MED. There was no statistically significant difference between corresponding doses of DEX and MED for any of the other parameters studied. Changes in sedation, analgesia and muscular relaxation were dose-dependent. It was concluded that anaesthetic effects of medetomidine in cats are probably due entirely to its d-isomer and that dexmedetomidine at 25, 50 and 75 μg/kg induces dose-dependent sedation, analgesia and muscular relaxation of clinical significance in cats.