Immobilization of free-ranging moose ( Alces alces ) with medetomidine-ketamine and remobilization with atipamezole

Seventeen free-ranging moose {Alces alces) (2 adult males, 13 adult females and 2 female calves) were immobilized with a combination of medetomidine hydochloride (MED) and ketamine hydrochloride (KET) in early autumn (August-September). Drugs were administrated with plastic projectile syringes fired from a dart gun, either from a car or by approaching the animals on foot. MED at 30 mg/adult and 15 mg/calf in combination with KET at 400 mg/adult and 200 mg/calf induced complete immobilization with sternal or lateral recumbency and loss of the corneal reflex in all individuals. The mean ± SD time from darting to when the animals were found was 18.3 ± 8.7 min for adults and the mean distance covered by these animals between darting and recumbency was 320 + 200 m. No side effects of clinical significance were detected and registration of the rectal temperature (38.8 ± 0.5°C), heart rate (44 ± 7 beats/min), respiratory rate (31 ±20 breaths/min) and relative arterial oxygen saturation (89 ± 3 %, n=8) during immobilization in adults showed that these physiological parameters were within the safe ranges established for moose. Blood samples from adults were analyzed for 17 haematological and 33 serum biochemical constituents and the results were compared to corresponding values found in moose immobilized with etorphine (ETO). Although the lower levels (p<0.05) found for haematocrit, red blood cells, haemoglobin and Cortisol in the MED-KET group may indicate a difference in the stress response, the low muscle enzyme levels in both groups show that these immobilizing drugs and capture methods induce very little physical stress in moose. A hyperglycaemic response was found in MED-KET treated animals. Atipamezole hydrochloride (ATI) rapidly remobilized all animals and the time elapsing from ATI administration to standing was 3-9 ± 1.8 min after i.v./s.c. treatment (n=7) and 6.9 ± 3.4 min after i.m./s.c. injection (n=8). No side effects were detected after reversal. In conclusion, medetomidine-ketamine and atipamezole can be recommended for reversible immobilization of free-ranging moose in early autumn.


Introduction
Etorphine has been the drug of choice for immobilization of free-ranging moose (Alces alces), both in Scandinavia (Sandegren et al., 1987) and in North America (Franzmann & Lance, 1988).Carfentanil, a more potent opioid than etorphine, has been used for moose capture in U.S.A. and Canada since 1984, mainly because a concentrated solution of etorphine was not commercially available (Franzmann & Lance, 1988).However, both agents are extremely toxic for humans (Haigh & Hudson, 1993) and there is a great need for a non-opioid alternative.
In recent years, medetomidine, a more potent alpha2-adrenoceptor agonist than xylazine, has been used in combination with ketamine for immobilization of various captive, non-domestic mammals (Jalanka, 1993)-Atipamezole, a potent and selective alpha2-adrenoceptor antagonist, is available for rapid and permanent reversal of the medetomidineunduced effects (Jalanka, 1993).Jalanka & Roeken (1990) reported the use of medetomidine-ketamine in captive moose, but complete and reliable immobilization was not achieved with the doses tested.In other cervids like Svalbard reindeer (Rangifer tarandus platyrhynchus) and red deer (Cervus elaphus) medetomidine-ketamine was found to be effective for chemical capture of free-living individuals (Tyler et al, 1990;Arnemo et al, 1994).
The aim of the present study was to evaluate medetomidine-ketamine and atipamezole for reversible immobilization of free-ranging moose in early autumn.a Time from darting to when the animal was found.k Distance covered by the animal between darting and recumbency.c Time from darting to administration of the antagonist.d> e Times from administration of the antagonist to head-lifting and standing, respectively.* Significant difference (p<0.0.5) between routes of administration.

Material and methods
when the animal lifted its head (head-up time) and to when it was standing (on-feet time) were recorded.
The ambient temperature during the trials ranged from 12 to 20°C.The animals were periodically tracked by radiotelemetry for up to two years after treatment.
Statistical calculations were performed with NCSS® (Number Cruncher Statistical System, Kaysville, Utah 84037, USA).The two-sample ttest was used to compare the head-up and on-feet times after i.v./s.c. and i.m./s.c.administration of ATI, respectively, and to compare haematological and serum biochemical values from moose treated with medetomidine-ketamine and etorphine, respectively.Logarithmic transformation was used for parameters that were not normally distributed (white blood cell and neutrophil counts, aspartate aminotransferase and creatinine).P-values <0.05 were considered to be significant.

Data on drug doses, induction times, physiological paramteres, times to reversal and head-up and onfeet times for adult animals are summarized in
Table 1.Medetomidine-ketamine induced complete immobilization with loss of the corneal reflex in both adults and calves.Due to the tracking procedure, the actual induction times are not known for all animals.However, three animals were observed going down, one adult female after 1.33 min and two calves close to their immobilized dams after 4.0 and 5.0 min, respectively.Most animals were found in sternal recumbency, they offered no resistance to handling and could easily be turned over to their sides.Examination of the calves revealed rectal temperatures of 39-9 and 40.0°C, heart rates of 58 and 68 beats/min and respiratory rates of 28 and 32 breaths/min.Clinical complications were not detected during immobilization.However, one adult female developed periodic apnoea 40 min after darting and was immediately given ATI i.v./s.c.without further evaluation of the severity of respiratory depression.This individual had twin calves and was in poor body condition.
Haematological and serum biochemical values are summarized in Tables 2 and 3, respectively.All treated animals recovered completely and no drug-related complications or behavioural changes were detected during the follow-up radiotracking study.In spring 1993, all females (n=4) with intact transmitters produced single calves.In spring 1994, only two out of seven females produced calves.Three females died from natural causes: one cow probably had dystocia and was found dead 9 months after tagging; one cow fell into a ditch 10 months after tagging and, although rescued, died within 24 hours; one cow drowned in a lake 17 months after tagging.One of the males lost the transmitter one month after tagging and was shot during the tegular hunt shortly afterwards.Both calves lost their transmitters during their first winter.One female was short during the regular hunt two months after tagging, while three females lost their transmitters 9, 10 and 15 months after tagging, respectively.

Discussion
The medetomidine-ketamine combination was very efficient for the capture of free-ranging moose.All animals became completely immobilized after one injection and no side effects of clinical significance were detected.Absence. of the corneal reflex in immobilized animals indicates that the depth of anaesthesia may be suitable for surgical intervention (Booth, 1988).
Rapid induction is essential in the chemical capture of wildlife so that the animals can be found, handled and monitored within a short time after drug administration.Due to the tracking procedu-  Although the normal body temperature in unmedicated free-ranging moose is not known, Franzmann et al. (1984) considered the safe range and the critical value for the rectal temperature in moose to be 38.4 -38.9 and 40.2°C, respectively.In the present study, immobilization with medetomidine-ketamine did not produce critical hyperthermia in any of the animals, even on sunny days with an ambient temperature of up to 20°C.Franzmann et al. (1984) reported the safe ranges and critical values for the heart and respiratory rates to be 70-91 and 103 beats/min, and 13-40 and 40 breaths/min, respectively.The bradycardia seen in all animals in the present study is probably a medetomidine-mediated effect (Jalanka, 1993).Although tachypnoea was recorded in a few individuals, a high relative arterial oxygen saturation was registered in all animals, indicating that ventilation is adequate during immobilization with medetomidin-ketamine.
The diuretic effect of alpha-2 adrenoceptor agonists is well established (Maze & Tranquilli, 1991;Jalanka, 1993) and explains why all the animals in the present study passed copious amounts of urine shortly after reversal.
Reference ranges for some blood values in moose have been reported by Franzmann & LeResche (1978).However, results from their study should be interpreted with caution, because pooled data from animals immobilized with different drugs and from animals killed during hunting were used.
According to Wesson et al. (1979), it is undesirable to combine and compare blood samples obtained by different methods such as shooting, immobilizing drugs or physical restraint.
Several blood stress parameters were significantly lower in animals treated with medetomidineketamine than in animals treated with etorphine.An increase in the haematocrit, red blood cell count, and hameoglobin and Cortisol concentrations is part of the animal's normal stress-response (Franzmann et al., 1975;Arnemo et al., 1994) and may indicate that etorphine-immobilization is more stressful to the animal.The hyperglycaemia found in animals treated with medetomidine-ketamine is a well-knwon alph^-adrenoceptor-mediated effect (Jalanka, 1993).Low levels of aspartate aminotransferase, creatine kinase and lactate dehydrogenase indicate that physical stress associated with capture was minimal in both groups of animals, and that muscle damage did not occur (Spraker, 1993).
Significant differences in some of the other blood parameters are probably unrelated to the drug effects: nutritional factors and body condition may influence the serum levels of proteins, minerals and metabolites (Franzmann & LeResche, 1978), while the difference in eosinophilic cell counts may indicate different parasitic burdens (Jain, 1986).Although Franzmann & LeResche (1978) did not find any sex differences in blood values during the summer/autumn season, the skewed sex distribution between animals treated with medetomidineketamine (mostly females) and those treated with etorphine (mostly males) may have influenced som of the results in the present study.
It is highly desirable that an effective reversal agent is available to shorten the recovery in captured wildlife, especially in ruminants which may develop life-threatening bloat and regurgitation while recumbent.In the present study, atipamezole rapidly remobilized the moose, both after i.v./s.c. and i.m./s.c.administration, and side effects were not seen.Because i.v.administration of atipamezole may cause ataxic recovery (Jalanka, 1993), I suggest that the i.m./s.c.route should be used on a routine basis.
Garner & Addison (1994) used yohimbine to reverse xylazine-ketamine immobilization in moose.Although yohimbine was given partly intravenously, the recovery was slow, the mean time from injection to standing being 22.8.min.The authors did not include information on side effects such as resedation.Yohimbine is a less potent and selective alpha2-adrenoceptor antagonist than atipamezole, especially in ruminants (Arnemo & Søli, 1993;Jalanka & Roeken, 1990), and may cause heavy resedation after the initial arousal effect (Jalanka & Roeken, 1990).
In conclusion, the present study showed medetomidine-ketamine and atipamezole to be excellent drugs for the reversible immobilization of freeranging moose under the described circumstances.
15 mg MED and 200 mg KET.To avoid disturbance during the induction phase, the standard procedure was to wait for 10 min after darting before tracking the animals with dogs (Norwegian elkhounds).The time from darting to when the animal was found («induction time») was recorded and the distance covered by the animal after darting (walking distance) was estimated.Immobilized animals were monitored (body posture and regularity and amplitude of respiration) to avoid clinical complications such as bloat and regurgitation and to detect signs of respiratory depression.The corneal reflex was used to assess the depth of anaesthesia in immobilized animals.five times the dose of MED (i.e. 150 mg ATI/adult and 75 mg ATI/calf) was administered to all animals for reversal of immobilization.The time from darting to injection of ATI (time to reversal) was recorded.The ATI dose was divided and given half i.v. and half s.c. in seven adults and one calf and half i.m. and half s.c. in eight adults and one calf.The times from ATI administration to

*
Significant difference (p<0.05) between groups.re, the actual induction time is unknown for most of the animals in the present study.However, the fact that three individuals were seen going down and that all the other animals were completely immobilized when found, strongly indicates that the actual times from darting to recumbency were probably much shorter than the recorded «induction» times (x=18.3min).Garner & Addison (1994) reported that the mean time from the first injection to recumbency for 22 free-ranging female moose immobilized with xylazine-ketamine in spring was 18.4 min and that all animals required multiple injections.Although these authors concluded that xylazine-ketamine was suitable for the immobilization and capture of moose, my data clearly indicate that medetomidineketamine is a better combination.There is no doubt that etorphine is an extremely safe drug for the immobilization of moose in winter.Approximately 970 captures of free-ranging individuals with etorphine have been carried out in Norway and only two drug-related fatalitites have occurred (M.Heim, pers.comm.1995).However, a major side effect of etorphine is hyperthermia and Franzmann (1982) discouraged immobilization of moose at ambient temperatures above 10°C.Reports on the use of xylazine in August -September(Miller & Litvaitis, 1992) and of xylazine-ketamine in May -June(Garner & Addison, 1994) did not include information about the body temperature or other physiological parameters in immobilized moose, or the ambient temperature during the studies.

Table 1 .
Summary of drug doses, induction times, walking distances, physiological parameters, times to reversal and head-up and on-feet times in adult, free-ranging moose immobilized with medetomidine-ketamine and remobilized with atipamezole in early autumn (Augst-September) 1992-1993 in Aust-Agder County, Norway.

Table 2 .
Haematological values in chemically immobilized free-ranging moose (Alces alces): a comparison between medetomidine-ketamine and etorphine.Data are given as mean + SD.