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.     

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.     

Medetomidine-ketamine in reindeer (Rangifer tarandus tarandus): effective immobilization by hand- and dart-administered injection.

Twelve reindeer (Rangifer tarandus tarandus) were immobilized by hand injection in indoor stalls with established optimal hand-injection doses of medetomidine-ketamine and then moved to outside paddocks where they were immobilized again with the same dose by dart. The reindeer in paddocks were immobilized a second time with a 50% higher dose, hereafter referred to as the optimal darting dose. Mean time to first sign of sedation was longer and mean induction time was significantly longer (55% and 79%, respectively) when the optimal hand-injection dose was dart injected versus hand injected. Mean time to first sign of sedation was not significantly shorter (although 21% shorter, numerically) but mean induction time was significantly shorter (30%) when animals were darted with the optimal darting dose versus darted with the optimal hand-injection dose. There were no significant differences in respiratory rate, rectal temperature, and relative arterial oxygen saturation in animals injected with different doses and by different routes. but there was a significantly lower heart rate in animals dart injected with the optimal darting dose versus dart injected with the optimal hand-injection dose. All animals responded at similar rates to atipamezole injection.     

Immobilization of mink (Mustela vison) with medetomidine-ketamine and remobilization with atipamezole

Four groups of mink were immobilized with medetomidine-HCl (MED) 0.1 mg/kg + ketamine (KET) 5 or 7.5 mg/kg at different ambient temperatures. The induction time, degree of immobilization and analgesia, rectal temperature, heart and respiration rates were recorded at intervals throughout the immobilization period. The animals were then given atipamezole-HCl (ATI) 0.5 mg/kg for reversal at different times after injection of MED/KET and the effects of the antagonist were evaluated.Subcutaneous administration of MED/KET induced complete immobilization in all 20 animals, and the highest dose was considered suitable for major surgery. Prolonged immobilization at low ambient temperatures (–10 to +5°C) caused severe hypothermia in all animals. The mean rectal temperature had dropped to 37.8°C and 32.1°C at 15 and 85 min, respectively, after injection of MED/KET, significantly lower than the corresponding values for animals immobilized at room temperature.Intramuscular administration of ATI 20 or 40 min after injection of MED/KET rapidly remobilized the animals without apparent side-effects. Administration of ATI to animals recovering spontaneously 90 min after injection of MED/KET induced thermogenesis (shivering) in animals immobilized at a low ambient temperature, while no such effect was seen in animals immobilized at room temperature. One hour after injection of ATI, the rectal temperatures of all treated animals had returned to normal and there were no signs of abnormal behaviour.     

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.     

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.     

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.     

Comparison of two pre-anaesthetic medetomidine doses in isoflurane anaesthetized sheep

OBJECTIVE: To compare the sedative, anaesthetic-sparing and arterial blood-gas effects of two medetomidine (MED) doses used as pre-anaesthetic medication in sheep undergoing experimental orthopaedic surgery. STUDY DESIGN: Randomized, prospective, controlled experimental trial. ANIMALS: Twenty-four adult, non-pregnant, female sheep of various breeds, weighing 53.9 +/- 7.3 kg (mean +/- SD). METHODS: All animals underwent experimental tibial osteotomy. Group 0 (n = 8) received 0.9% NaCl, group L (low dose) (n = 8) received 5 microg kg(-1) MED and group H (high dose) (n = 8) received 10 microg kg(-1) MED by intramuscular (IM) injection 30 minutes before induction of anaesthesia with intravenous (IV) propofol 1% and maintenance with isoflurane delivered in oxygen. The propofol doses required for induction and endtidal isoflurane concentrations (F(E')ISO) required to maintain anaesthesia were recorded. Heart and respiratory rates and rectal temperature were determined before and 30 minutes after administration of the test substance. The degree of sedation before induction of anaesthesia was assessed using a numerical rating scale. Arterial blood pressure, heart rate, respiratory rate, FE'ISO, end-tidal CO2 (FE'CO2) and inspired O2 (FIO2) concentration were recorded every 10 minutes during anaesthesia. Arterial blood gas values were determined 10 minutes after induction of anaesthesia and every 30 minutes thereafter. Changes over time and differences between groups were examined by analysis of variance (anova) for repeated measures followed by Bonferroni-adjusted t-tests for effects over time. RESULTS: Both MED doses produced mild sedation. The dose of propofol for induction of anaesthesia decreased in a dose-dependent manner: mean (+/-SE) values for group 0 were 4.7 (+/-0.4) mg kg(-1), for group L, 3.2 (+/-0.4) mg kg(-1) and for group H, 2.3 (+/-0.3) mg kg(-1)). The mean (+/-SE) FE'ISO required to maintain anaesthesia was 30% lower in both MED groups [group L: 0.96 (+/-0.07) %; group H: 1.06 (+/-0.09) %] compared with control group values [(1.54 +/- 0.17) %]. Heart rates were constantly higher in the control group with a tendency towards lower arterial blood pressures when compared with the MED groups. Respiratory rates and PaCO2 were similar in all groups while PaO2 increased during anaesthesia with no significant difference between groups. In group H, one animal developed a transient hypoxaemia: PaO2 was 7.4 kPa (55.7 mmHg) 40 minutes after induction of anaesthesia. Arterial pH values and bicarbonate concentrations were higher in the MED groups at all time points. CONCLUSION AND CLINICAL RELEVANCE: Intramuscular MED doses of 5 and 10 microg kg(-1) reduced the propofol and isoflurane requirements for induction and maintenance of anaesthesia respectively. Cardiovascular variables and blood gas measurements remained stable over the course of anaesthesia but hypoxaemia developed in one of 16 sheep receiving MED.     

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.     

Reversible anaesthesia of free-ranging lions (Panthera leo) in Zimbabwe

The combination of medetomidine-zolazepam-tiletamine with subsequent antagonism by atipamezole was evaluated for reversible anaesthesia of free-ranging lions (Panthera leo). Twenty-one anaesthetic events of 17 free-ranging lions (5 males and 12 females, body weight 105-211 kg) were studied in Zimbabwe. Medetomidine at 0.027-0.055 mg/kg (total dose 4-11 mg) and zolazepam-tiletamine at 0.38-1.32 mg/kg (total dose 50-275 mg) were administered i.m. by dart injection. The doses were gradually decreased to improve recovery. Respiratory and heart rates, rectal temperature and relative haemoglobin oxygen saturation (SpO2) were recorded every 15 min. Arterial blood samples were collected from 5 lions for analysis of blood gases and acid-base status. For anaesthetic reversal, atipamezole was administered i.m. at 2.5 or 5 times the medetomidine dose. Induction was smooth and all lions were anaesthetised with good muscle relaxation within 3.4-9.5 min after darting. The predictable working time was a minimum of 1 h and no additional drug doses were needed. Respiratory and heart rates and SpO2 were stable throughout anaesthesia, whereas rectal temperature changed significantly over time. Atipamezole at 2.5 times the medetomidine dose was sufficient for reversal and recoveries were smooth and calm in all lions independent of the atipamezole dose. First sign of recovery was observed 3-27 min after reversal. The animals were up walking 8-26 min after reversal when zolazepam-tiletamine doses < 1 mg/kg were used. In practice, a total dose of 6 mg medetomidine and 80 mg zolazepam-tiletamine and reversal with 15 mg atipamezole can be used for either sex of an adult or subadult lion. The drugs and doses used in this study provided a reliable, safe and reversible anaesthesia protocol for free-ranging lions.     

Field anesthesia of wild ring-tailed lemurs (Lemur catta) using tiletamine-zolazepam, medetomidine, and butorphanol

Telazol has been commonly used for field anesthesia of wild lemurs, including ring-tailed lemurs (Lemur catta). Telazol alone provides good induction, but doesn't cause adequate muscle relaxation and sedation for collecting consistent somatic measurements and high-quality dental impressions that are sometimes needed. Variability in induction response has been seen between individuals that have received similar dosages, with young lemurs seeming to need more anesthetic than mature lemurs. This investigation evaluated Telazol induction in young (2.0-4.9 yr) and mature (> or = 5.0 yr) ring-tailed lemurs and compared postinduction supplementation with medetomidine or medetomidine-butorphanol. Forty-eight lemurs were anesthetized with Telazol administered via blow dart; then, 20 min after darting, they were supplemented via hand injection with either medetomidine (0.04 mg/ kg) or medetomidine-butorphanol (0.04 mg/kg and 0.2 mg/kg, respectively). The odds ratio for young lemurs to need more than one dart for induction, relative to mature lemurs, was 3.8, even though the initial dose of Telazol received by young lemurs (19 +/- 7 mg/kg) was significantly higher than the initial dose administered to mature lemurs (12 +/- 5 mg/kg). The total Telazol dosage was also significantly different between young lemurs (33 +/- 15 mg/kg) and mature lemurs (18 +/- 9 mg/kg). Both medetomidine and medetomidine-butorphanol provided good muscle relaxation and sedation for all procedures. Physiologic values were similar between the two protocols. Oxygen saturation by pulse oximetry was generally good, although there were a few SaO2 values < 90%. Recoveries were smooth, but long. Time to head up was correlated with total Telazol dosage in mature lemurs. In young lemurs, time to standing was correlated with Telazol induction dosage and time of last Telazol administration. Lemurs that received hand injections of Telazol took longer to recover than those that did not. Further refinements are needed to increase induction reliability and to decrease recovery time, particularly in young lemurs.     

Effect of propofol at two injection rates or thiopentone on post-intubation apnoea in the dog

Ventilatory effects at induction of anaesthesia were studied following intubation in 66 dogs anaesthetised using thiopentone (10 mg/kg) or propofol (4 mg/kg, injected rapidly or 4 mg/kg, injected slowly). Acepromazine and morphine preanaesthetic medication was administered, and anaesthesia was maintained with halothane in nitrous oxide and oxygen. The time from connection of the breathing system to the first breath was measured. Apnoea was defined as cessation of spontaneous respiration for 15 seconds or longer. Respiratory rate and minute volume were measured for the first five minutes of anaesthesia. Propofol was associated with a greater incidence of apnoea than thiopentone (59 per cent and 64 per cent compared with 32 per cent), but this difference was not statistically significant. Time to first breath was significantly longer with propofol than thiopentone and longest with the slower injection of propofol (P<0.05) (median of four seconds for thiopentone, 19.5 seconds for the propofol rapid injection, and 28.8 seconds for the propofol slow injection). In conclusion, the induction agent and speed of injection affect the incidence and duration of post-intubation apnoea.     

Carprofen as an analgesic for postoperative pain in cats: Dose titration and assessment of efficacy in comparison to pethidine hydrochloride

The aim of this study was to titrate the optimal dose of carprofen for single dose usage, for alleviating postoperative pain, under a double-blind and randomised protocol, using both negative and positive controls. Renal tolerance was assessed by screening plasma urea and creatinine. Pre- and postoperative assessment of pain and sedation was made using a dynamic and interactive visual analogue scoring system in 60 cats undergoing ovariohysterectomy. The cats were randomly assigned to one of six groups: (1) carprofen at 1-0 mg/kg subcutaneously (sc); (2) carprofen at 2-0 mg/kg sc; (3) carprofen at 4-0 mg/kg sc; (4) pethidine at 5-0 mg/kg intramuscularly (im), (5) pethidine at 10-0 mg/kg im; and (6) no analgesics (injection of saline). All injections were given postoperatively on tracheal extuba-tion and administered in a double-blind manner. Assessments were made up to 20 hours post extubation. Prior to induction and at 20 hours post extubation, blood samples were taken for laboratory analysis of the urea and creatinine content to check for any adverse effect on renal function. Cats given pethidine did not appear more sedated than the groups receiving carprofen or saline. Cats receiving carprofen were in less pain postoperatively overall, with 4-0 mg/kg being the most effective dose rate (significantly better than the other doses of carprofen at four and eight hours post extubation). The highest dose of pethidine provided significantly better analgesia than the highest dose of carprofen up to two hours post extubation, but from two to 20 hours post extubation carprofen at 4-0 mg/kg provided significantly better analgesia than the pethidine. None of the analgesic regimens appeared to affect renal function adversely, as measured by urea and creatinine levels.     

Evaluation of butorphanol-azaperone-medetomidine in captive cheetah (Acinonyx jubatus) immobilization

Objective

The butorphanol-azaperone-medetomidine fixed-dose combination (BAM, respectively, 30-12-12 mg mL^?1) with subsequent antagonism by naltrexone-atipamezole was evaluated for reversible immobilization of captive cheetahs (Acinonyx jubatus).

The disappearance rate in reindeer of famphur an organophosphorus parasiticide

The present investigations were carried out in order to study the disappearance rate in reindeer of famphur (0,O-dimethyl-O,p-(NtN-di-methylsulphamoyl) phenyl phosphorothioate), a promising systemic parasiticide for the control of reindeer warble and nostril flies.The compound was administered intramuscularly to reindeer as a single dose (in the form of the preparation Warbcx). At a dose of 20 mg/kg body weight (2 animals) famphur caused inhibition of plasma and erythrocyte cholinesterase activities by about 50 %. The plasma esterase activity fell off rapidly, within 24 hrs., and returned to normal within 3 weeks, whereas the erythrocyte esterase activity decreased gradually and remained low for at least 4 weeks after dosing.Peak plasma levels of fampliiir, varying between 1 and 16 p.p.m., were attained within 5–33 hrs., after a dose of 30 mg famphur per kg body weight (7 reindeer). The plasma levels declined to below 0.02 p.p.m. in 72–96 hrs. Famoxon, the oxygen analogue of famphur, was observed for 1–2 days in plasma at low levels, amounting to about 10 % of the corresponding famphur levels. In erythrocytes practically no residues were found of either compound.Tissue residue levels were low — except at the injection site. In a series of animals given a dose of 30 mg/kg body weight and killed at varying times after treatment famphur or famoxon were detectable in liver for 4.5 days and in kidney and skeletal muscle remote from the injection site for 12 days. In muscle tissue from the injection site highly variable residue levels were observed, indicating absorption from the intramuscular depot to be erratic.The experimental results suggest that no appreciable consumer hazard would arise from a proposed single-dose intramuscular treatment of reindeer with famphur at a dosage not exceeding 30 mg/kg body weight, provided a minimum interval of 3 weeks is maintained between treatment and slaughter and the muscle tissue around the injection site is discarded.     

Xylazine as an immobilizing agent for captive white-tailed deer.

Xylazine, at dosages of 0.89 to 8.00 mg/kg of body weight, was injected intramuscularly by manual or projectile syringe into 68 captive white-tailed deer (Odocoileus virginianus) to facilitate handling. Of 63 deer given the intended dose, 59 were moderately to deeply sedated and immobilized. Deer began to react visibly within 0.75 to 4.25 minutes after injection. Mean induction time (+/- SD) was 5.15 +/- 4.08 minutes and mean duration of immobilization was 197.90 +/- 101.13 minutes. Other than the prolongation of immobilization at dosages larger than or equal to 3 mg/kg, these times were not significantly affected by dosage or sex of the deer. Induction times were shorter in fawns than in older deer and much shorter in freshly trapped deer than in deer that had been trapped but kept undisturbed in semidarkened pens for 6 to 48 hours or in deer that were semitame captives. Dosages as low as 0.89 mg/kg were effective, and the safety margin appeared to be at least 8 times the minimal effective dose; however, immobilized deer were frequently unable to maintain sternal recumbency and required attention throughout the period of immobilization.     

Effects of dexamethasone on emesis in cats sedated with xylazine hydrochloride

OBJECTIVE: To determine antiemetic efficacy of prophylactic administration of dexamethasone and its influence on sedation in cats sedated with xylazine hydrochloride. ANIMALS: 6 healthy adult cats (3 males and 3 females). PROCEDURE: The prophylactic antiemetic effect of 4 doses of dexamethasone (1, 2, 4, and 8 mg/kg of body weight, IM) or saline (0.9% NaCl) solution (0.066 ml/kg, IM) administered 1 hour before administration of xylazine (0.66 mg/kg, IM) was evaluated. Cats initially were given saline treatment (day 0) and were given sequentially increasing doses of xylazine on days 7, 14, 21, and 28. After xylazine injection, all cats were observed for 30 minutes to allow assessment of frequency of emesis and time until onset of the first emetic episode.The influence of dexamethasone on xylazine-induced sedation in these cats also was evaluated. RESULTS: Prior treatment with 4 or 8 mg/kg of dexamethasone significantly reduced the frequency of emetic episodes and also significantly prolonged the time until onset of the first emetic episode after xylazine injection. Time until onset of the first emetic episode also was significantly prolonged for dexamethasone at a dose of 2 mg/kg. Time until onset of sedation after administration of xylazine was not altered by administration of dexamethasone. CONCLUSIONS AND CLINICAL RELEVANCE: Dexamethasone (4 or 8 mg/kg, IM) significantly decreased the frequency of emetic episodes induced by xylazine without compromising sedative effects in cats. Dexamethasone may be used prophylactically as an antiemetic in cats treated with xylazine.     

Immobilization of Norwegian reindeer (Rangifer tarandus tarandus) and Svalbard Reindeer (R. t. platyrhynchus) with medetomidine and medetomidine-ketamine and reversal of immobilization with atipamezole

The sedative action of medetomidine (-ketamine) was studied in 12 captive Norwegian semidomesticated reindeer (NR), including 4 newborn calves, and in 7 free-living Svalbard reindeer (SR). Medetomidine, with or without ketamine, caused effective, reliable immobilization in NR. Doses of 50-200 micrograms/kg medetomidine alone or 30-125 micrograms/kg medetomidine combined with greater than or equal to 300 micrograms/kg ketamine induced complete immobilization, good muscle relaxation and persistent, deep sedation with little respiratory depression in NR; SR required higher doses. Atipamezole successfully antagonized medetomidine (-ketamine) resulting in rapid and persistent reversal of immobilization in all cases (NR and SR). Both medetomidine and atipamezole had wide safety margins and no conspicuous lasting side effects after reversal.     

Anesthesia induced by administration of xylazine hydrochloride alone or in combination with ketamine hydrochloride and reversal by administration of yohimbine hydrochloride in captive Axis deer (Axis axis)

OBJECTIVE: To determine the anesthetic dose and cardiopulmonary effects of xylazine hydrochloride when used alone or in combination with ketamine hydrochloride and evaluate the efficacy of yohimbine hydrochloride to reverse anesthetic effects in captive Axis deer. ANIMALS: 35 adult (10 males and 25 females) Axis deer (Axis axis). PROCEDURES: All deer were anesthetized by IM administration of xylazine (3.5 mg/kg; experiment 1), a combination of ketamine and xylazine (1.25 and 1.5 mg/kg, respectively; experiment 2), or another combination of ketamine and xylazine (2.5 and 0.5 mg/kg, respectively; experiment 3). In addition, female deer were also anesthetized by IM administration of a third combination of ketamine and xylazine (1.5 and 1 mg/kg, respectively; experiment 4). Ten to 40 minutes after induction, anesthesia was reversed by IV administration of yohimbine (5, 8, or 10 mg). RESULTS: In male deer, experiment 3 yielded the most rapid induction of anesthesia. In females, experiment 4 yielded the best induction of anesthesia without adverse effects. All doses of yohimbine reversed anesthesia. Duration of anesthesia before administration of yohimbine had no effect on recovery time. CONCLUSIONS AND CLINICAL RELEVANCE: A combination of ketamine and xylazine can be used to induce anesthesia in Axis deer. Furthermore, anesthetic effects can be reversed by administration of yohimbine.     

Chemical immobilization of chimpanzees (Pan troglodytes) using a combination of detomidine and ketamine

Objective To determine if a combination of detomidine and ketamine can be used for effective chemical immobilization of chimpanzees. Study design Observational study. Animals Twenty‐one adult captive chimpanzees (12 males, nine females), age 8–46 years, weighing 40.4–68.4 kg. Methods The chimpanzees were immobilized with intramuscular (IM) detomidine and ketamine by a darting system. Based on estimated weights, doses administered were 50 μg kg^?1 detomidine and 4 mg kg^?1 ketamine in groups 1 and 2, and 60 μg kg^?1 and 5 mg kg^?1 respectively in group 3. Eight minutes in group 1 and 15 minutes in groups 2 and 3 were allowed from the time of apparent immobilization before removing the animals from their enclosures. Body temperature, arterial haemoglobin saturation and pulse rate were measured. The time from injection to induction (recumbency and absence of voluntary movement), total anaesthetic and recovery times (with or without atipamezole) were recorded. Results Immobilization occurred within 5 minutes after darting in most animals. Early handling of the chimpanzees often resulted in arousal and required further doses of ketamine IM. Most animals were hypoxaemic and hypothermic. Occasionally, bradycardia was observed. Atipamezole resulted in an acceptable quality of recovery 10 minutes after IM injection. The duration of immobilization varied widely when no antagonist was administered. Conclusions and clinical relevance The combination detomidine (60 μg kg^?1) and ketamine (5–6 mg kg^?1) can be used for the immobilization of chimpanzees for non‐ to minimally invasive procedures. A period of 15 minutes should be allowed before handling to avoid unwanted arousal. Oxygen administration is recommended to reduce hypoxaemia. Administration of atipamezole is justified to hasten recovery.