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SHORT COMMUNICATION |
National Park Service, Pictured Rocks Science Center, Box 40, Munising, Michigan 49862, USA (email: jerry_belant{at}nps.gov)
ABSTRACT:
The effectiveness of tiletamine plus zolazepam (Telazol) and xylazine was evaluated as an immobilizing combination for raccoons (Procyon lotor). Fifteen raccoons were injected intramuscularly with a 3:2 mixture of Telazol (3.2±0.6 mg/kg [mean±SD]) and xylazine (2.1±0.4 mg/kg) at Pictured Rocks National Lakeshore, Michigan, USA, during May–October, 2001–03. Mean induction time was 4.8±3.8 min; mean recovery time was 128.5±48.4 min. No linear relationships were found between the amount (mg/kg) of Telazol-xylazine injected and induction (r2 = 0.06, P = 0.40) or recovery times (r2 = 0.01, P = 0.78). Mean heart rate, respiratory rate, and body temperature declined through 20 min after induction (P< 0.05). No mortality occurred and no short-term adverse effects were observed in recaptured individuals. I conclude that a 3:2 mixture of Telazol-xylazine is a safe and effective immobilizing agent for raccoons when conducting nonsurgical field procedures. Immobilizing raccoons with Telazol at 3 mg/kg and xylazine at 2 mg/kg should provide up to 60 min of handling time and usually allow full recovery in about 120 min.
Key words: Chemical immobilization, field study, Procyon lotor, raccoon, Telazol, tiletamine, xylazine, zolazepam.
Field immobilization of raccoons (Procyon lotor) has been conducted with several injectable anesthetics, including sodium pentobarbital (Mech, 1965), ketamine (Bigler and Hoff, 1974; Gregg and Olson, 1975), ketamine-xylazine (Deresienski and Rupprecht, 1989; Belant, 1995), and Telazol (Gehrt et al., 2001). Kreeger (1999) recommended a 5:1 combination of ketamine at 20 mg/kg and xylazine at 4 mg/kg, with alternative drugs of ketamine at 20 mg/kg and acepromazine at 0.1 mg/kg or Telazol at 12 mg/kg.
Telazol (100 mg/ml, Fort Dodge Animal Health, Fort Dodge, Iowa, USA) contains a 1:1 combination of tiletamine and zolazepam and has been used effectively on numerous wildlife species (e.g., Mitcheltree et al., 1999; Golden et al., 2002). Advantages of Telazol include a high therapeutic index, minimal respiratory effects, and good cardiovascular support (Kreeger, 1999). Xylazine (Xyla-ject®, 100 mg/ml, Phoenix Pharmaceutical Inc., St. Joseph, Missouri, USA) is an alpha2-adrenergic tranquilizer also used to immobilize wildlife, typically in combination with other anesthetics (Kreeger, 1999). Telazol-xylazine has been used on several ungulate species, including white-tailed deer (Odocoileus virginianus) and bighorn sheep (Ovis canadensis) (Kilpatrick and Spohr, 1999; Merwin et al., 2000; Murray et al., 2000). For carnivores, Cattet et al. (2001) successfully used this immobilizing combination on grizzly bears (Ursus arctos); use of Telazol-xylazine for immobilizing raccoons has not been reported. My objective was to assess effectiveness of Telazol-xylazine for field immobilization of raccoons.
The study was conducted from May to October, 2001–03, at Pictured Rocks National Lakeshore, central Upper Peninsula of Michigan, USA (46°27'N, 86°33'W). Ambient temperatures during the study ranged from about 4 C to 30 C. Raccoons were captured in live traps (model 108, Tomahawk Live Trap Company, Tomahawk, Wisconsin, USA) baited with sardines or chicken and commercial trapping lures. Raccoons were captured incidental to a study of fisher (Martes pennanti) and American marten (Martes americana). After visually estimating body weight, all raccoons were intramuscularly injected in the gluteus maximus, gluteus medius, or vastus laterallis by using a 1-ml syringe containing a 3:2 combination of Telazol and xylazine. Each 500-mg vial of Telazol was reconstituted with 5 ml of sterile water to create the 100-mg/ml solution. Xylazine (333 mg; 3.33 ml) was then added to the Telazol solution to create the 3:2 Telazol-xylazine combination.
Procedures used to document raccoon response to immobilization followed those of Belant (1991). Induction time was defined as the interval between injection and lack of responsiveness to tactile stimuli. Recovery time was the interval between immobilization and the animal’s ability to maintain an upright posture and respond to external stimulation, including moving within the live trap to different positions. Rectal temperature, respiratory rate, and resting heart rate were recorded as soon as practical after immobilization (
3 min) and at 10 and 20 min after induction. Rectal temperature was recorded with a digital thermometer. Respiratory rate was determined by counting complete thoracic cycles (inhalation and exhalation) for 30 or 60 sec. Resting heart rate was determined by placing fingertips against the raccoon’s chest and counting beats for 30 or 60 sec. Each raccoon was weighed and received a tag in each ear (model 1005-1, National Band and Tag Company, Newport, Kentucky, USA). Three raccoons received radiotransmitters attached with a collar (Advanced Telemetry Systems, Inc., Isanti, Minnesota, USA). Raccoons were returned to their live traps after handling procedures were completed. Animals were released at the capture site upon full recovery. Linear regression (Zar, 1984) was used to determine the relationships between dose and time to first effect, induction time, and recovery time. Repeated measures analysis of variance (Zar, 1984) was used to compare heart rate, respiratory rate, and rectal temperature at 0, 10, and 20 min after induction. Means are reported with ±1 SD; statistical significance was established as P0.05.
The 15 raccoons (11 males and four females) that were captured and immobilized weighed 2.2–9.3 kg. Mean doses of Telazol and xylazine injected were at dosages of 3.2±0.6 and 2.1±0.4 mg/kg, respectively. No additional injections were required to sustain sedation during handling procedures.
Mean time to first effect of the drugs was 1.7±0.6 min and mean induction time was 4.8±3.8 min (Table 1
). Full recovery from immobilization occurred in 128.5±48.4 min. No linear relationships were found between dose and time to first effect (r2 = 0.01, P = 0.84), dose and induction time (r2 = 0.06, P = 0.40), or dose and recovery time (r2 = 0.01, P = 0.78). No differences were found in mean heart rate (F = 1.18; df = 2,41; P = 0.32), respiratory rate (F = 0.54; df = 2,41; P = 0.59), or body temperature (F = 0.41; df = 2,41; P = 0.67) from 0 min to 20 min after induction. Physiologic parameters of one raccoon recorded at 30 min after induction demonstrated it remained stable after 20 min. Although depth of anesthesia was not evaluated quantitatively, raccoons did not respond to attachment of ear tags.
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Telazol and xylazine doses used for live-trapped raccoons in this study provided satisfactory induction times and adequate anesthesia for minor field procedures. Cattet et al. (2001) successfully used a 3:2 combination of Telazol and xylazine at 5 mg/kg to immobilize grizzly bears. Gehrt et al. (2001) used Telazol 5 mg/kg to immobilize raccoons in Illinois but provided no data on induction or recovery times. Based on available literature, Kreeger (1999) recommended ketamine at 20 mg/kg and xylazine at 4 mg/kg. That lower doses were used successfully in this study is in part because Telazol is about 2.5 times more potent than ketamine (Beck, 1972).
Although recovery times I observed were not unusually long, additional studies could be conducted to assess effects of varying doses and combinations of Telazol and xylazine on recovery time. The lowest dosage used on a raccoon in this study was Telazol and xylazine at 2.3 and 1.5 mg/kg, respectively. Induction and recovery times for this individual were 10 and 125 min, respectively. Thus, lower mean doses than reported in this study may provide adequate anesthesia in raccoons. Use of an antagonist such as yohimbine could further reduce recovery times. Finally, use of a Telazol-medetomidine combination for raccoon immobilization should be explored.
A 3:2 mixture of Telazol and xylazine is a safe and effective immobilization agent for raccoons for minor field procedures. Although raccoons in this study were immobilized with this mixture at dosages ranging from 3.8 mg/kg to 8.2 mg/kg, I recommend using combined drugs at 5 mg/kg (Telazol at 3 mg/kg and xylazine at 2 mg/kg) for standard field procedures (e.g., tooth extraction, radiotagging, and blood sampling). This dosage will provide 60 min of handling time and allow full recovery in about 120 min.
Funding for this study was provided by Pictured Rocks National Lakeshore and the National Park Service Challenge Cost Share Program. A. Hales, N. Lapinski, L. Kainulainen, L. Kruger, and K. Stanley provided field assistance. Trapping and handling procedures conformed to the American Society of Mammalogists Guidelines for the Capture, Handling, and Care of Mammals (Animal Care and Use Committee, 1998) and Pictured Rocks National Lakeshore Capture Operations Protocol.
ANIMAL CARE AND USE COMMITTEE. 1998. Guidelines for the capture, handling, and care of mammals as approved by the American Society of Mammalogists. Journal of Mammalogy 79:1416–1431.
BECK, C. C. 1972. Chemical restraint of exotic species. Journal of Zoo Animal Medicine 3: 3–66.
BELANT, J. L. 1991. Immobilization of fishers (Martes pennanti) with ketamine hydrochloride and xylazine hydrochloride. Journal of Wildlife Diseases 27: 328–330.[Abstract]
———. 1995. Field immobilization of raccoons with ketamine hydrochloride and xylazine hydrochloride. Acta Theriologica 40: 327–330.
BIGLER, W. J., AND G. L. HOFF. 1974. Anesthesia of raccoons with ketamine hydrochloride. Journal of Wildlife Management 38: 364–366.
CATTET, M. R. L., N. A. CAULKETT, AND G. B. STENHOUSE. 2001. The comparative effects of chemical immobilizing drug and method of capture on the health of grizzly bears. Thirteenth International Conference on Bear Research and Management, May 20–26, Jackson, Wyoming, p. 40 [Abstract].
DERESIENSKI, D. T., AND C. E. RUPPRECHT. 1989. Yohimbine reversal of ketamine-xylazine immobilization of raccoons (Procyon lotor). Journal of Wildlife Diseases 25: 169–174.[Abstract]
GEHRT, S. D., L. L. HUNGERFORD, AND S. HATTEN. 2001. Drug effects on recaptures of raccoons. Wildlife Society Bulletin 29: 833–837.
GOLDEN, H. N., B. S. SHULTS, AND K. E. KUNKEL. 2002. Immobilization of wolverines with Telazol from a helicopter. Wildlife Society Bulletin 30: 492–497.
GREGG, D. A., AND L. D. OLSON. 1975. The use of ketamine hydrochloride as an anesthetic for raccoons. Journal of Wildlife Diseases 11: 335–337.
KILPATRICK, H. J., AND S. M. SPOHR. 1999. Telazol-xylazine versus ketamine-xylazine: A field evaluation for immobilizing white-tailed deer. Wildlife Society Bulletin 27: 566–570.
KREEGER, T. J. 1999. Handbook of wildlife chemical immobilization. 3rd Edition. Wildlife Pharmaceuticals, Fort Collins, Colorado, 342 pp.
MECH, L. D. 1965. Sodium pentobarbital as an anesthetic for raccoons. Journal of Mammalogy 46: 343–344.
MERWIN, D. S., J. J. MILLSPAUGH, G. C. BRUNDIGE, D. SCHULTZ, AND C. L. TYNER. 2000. Immobilization of free-ranging Rocky Mountain bighorn sheep, Ovis canadensis canadensis, ewes with Telazol and xylazine hydrochloride. Canadian Field-Naturalist 114: 471–475.
MITCHELTREE, D. H., T. L. SERFASS, W. M. TZILKOWSKI, R. L. PEPER, M. T. WHARY, AND R. P. BROOKS. 1999. Physiological responses of fishers to immobilization with ketamine, ketamine-xylazine, or Telazol. Wildlife Society Bulletin 27: 582–591.
MURRAY, S., S. L. MONFORT, L. WARE, W. J. MC-SHEA, AND M. BUSH. 2000. Anesthesia in female white-tailed deer using telazol and xylazine. Journal of Wildlife Diseases 36: 670–675.[Abstract]
ZAR, J. H. 1984. Biostatistical analysis. 2nd Edition. Prentice Hall, Inc., Englewood Cliffs, New Jersey, 718 pp.
Received for publication 3 July 2003.
This article has been cited by other articles:
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  J. L. Belant Tiletamine-Zolazepam-Xylazine Immobilization of American Marten (Martes americana) J. Wildl. Dis., July 1, 2005; 41(3): 659 - 663. [Abstract] [Full Text] [PDF]
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