Abstract

With the increased interest in captive propagation of elephants, an increasing number of zoos are keeping, or anticipate holding, herds of breeding elephants. Many zoos will elect to handle these animals using protected or semi-protected contact. Both of these handling systems will increase the need to chemically restrain elephants for husbandry and medical procedures. Many procedures can be performed without need for lateral recumbency, but the literature regarding standing sedation or tranquilization of elephants, especially African elephants (Loxodonta africana), is sparse. This paper reviews 27 standing tranquilization and sedation events of eight (one male and seven female) African elephants held at the Knoxville (Tennessee) Zoo for immobilization dosages, rating, and adverse effects.

All elephants were considered sexually mature, with ages at time of immobilization ranging from 12 to 35+ yr. Actual weights were not available, so all dosages reported are estimations. Estimated body weights ranged from 3000-5000 kg. Food was withheld from the animals beginning the night prior to immobilization. Water was withheld, when possible, from early (0700 to 0800 hr) the day of the immobilization. Initial drug administration was by aluminum darts and CO₂ pistol (Palmer Cap-Chur Equipment Inc., Douglasville, GA 30133 USA) for non-tractable animals and by hand injection for more tractable animals. All animals remained standing throughout each procedure. Monitoring of the procedures was limited to visual observations. No adverse effects were observed during any immobilization.

Intramuscular azaperone (Stresnil®; Janssen, Toronto, Ontario M3C 1L9, Canada) was used to tranquilize seven animals for a total of 20 immobilizations (Table 1). Azaperone alone or in combination with local anesthesia (lidocaine blocks) was used 15 times. Reasons for tranquilization included treatment of tail folliculitis, treatment of abscesses, obtaining blood samples, intradermal tuberculin testing, and manual stimulation of ejaculation. Dosages for azaperone alone ranged from 0.056-0.107 mg/kg (median dosage = 0.08 mg/kg; total doses ranged from 240-400 mg/animal). One animal, which received an initial dosage of 0.04 mg/kg required supplementation, to a total dosage of 0.056 mg/kg, to be tractable enough, while in an elephant restraint device, for manual stimulation of ejaculation. All but one tranquilization were rated as good (sufficient tranquilization to accomplish the procedure) or excellent (sufficient tranquilization to perform the intended procedure and additional diagnostics). Tranquilized elephants stood, with minimal swaying, and did not make efforts to resist or pull away for the handler. Tranquilization of one female that received 0.075 mg/kg was rated as fair due to insufficient sedation for venipuncture. One tranquilization was rated good (dosage = 0.107 mg/kg) but a notation suggested the elephant was "too deep, tried to buckle" and a lesser dosage was used more satisfactorily on that animal for subsequent immobilizations. Tranquilizations ranked excellent were produced by dosages of 0.079-0.094 mg/kg (n = 4). Times from initial darting to adequate sedation and to recovery (normal behavior) were infrequently recorded but the author's impression is that animals became sedate for handling approximately 20 min after injection and recovered approximately 2 hr after initial dosing.

Intramuscular azaperone in combination with butorphanol (Torbugesic®; Fort Dodge Lab, Fort Dodge, IA 50501-0518 USA) was used on one female elephant for aggressive debridements of a facial abscess and on another aggressive cow. These azaperone dosages were slightly greater, ranging from 0.068-0.12 mg/kg, than those described above. In one immobilization 10 mg butorphanol was mixed with the azaperone (0.12 mg/kg) in the initial dart (tranquilization was rated good). In the other procedures butorphanol, 0.006-0.014 mg/kg (total doses = 20-50 mg), was given i.v. 24-73 min post-azaperone administration, to attain (0.006 mg/kg given at 24 and 25 min) or maintain (0.013 and 0.014 mg/kg given at 40 and 73 min, respectively) control. The azaperone and butorphanol combination sedation events were ranked good (n = 3) or excellent (n = 2). Naloxone (Abbott Laboratories, North Chicago, IL 60064 USA; 0.004 mg/kg i.v.; total dose = 12.8 mg) was used to reverse the effects of butorphanol in the animal receiving the highest butorphanol dosage.

Xylazine (Rompun®; Miles Inc., Animal Health Products, Shawnee, KS 66201 USA) at dosages of 0.18-0.33 mg/kg (total doses 600-1000 mg) was used alone (n = 3) to sedate three female elephants to load into a trailer. Each animal was walked approximately 50 m and stepped onto a trailer. These procedures were successful (the animals were ultimately loaded) but each sedation was rated fair.

Xylazine in combination with butorphanol was used to sedate 2 animals, twice each. The adult male elephant (estimated weight = 5000 kg) received a total dose of 800 mg (0.16 mg/kg) xylazine i.m., and 26 min later received 180 mg (0.036 mg/kg) butorphanol i.v. for radiology, performed outside of the elephant restraint device. This immobilization was rated excellent but when same dosages were used 2 yr later, the immobilization was initially rated as only good. Supplemental butorphanol (20 mg) was given during the second immobilization 77 min after the xylazine injection and the subsequent phase of the immobilization was rated as fair. One female elephant (estimated weight = 3500 kg) received 100 mg (0.035 mg/kg) xylazine i.v. mixed with 15 mg (0.005 mg/kg) butorphanol i.v. Fourteen minutes later an additional 50 mg xylazine and 10 mg butorphanol were given i.v. A local block was subsequently used to lance a subcutaneous abscess on the abdomen and this immobilization was rated good. On a subsequent immobilization for physical examination and blood collection, this animal received 500 mg (0.14 mg/kg) xylazine i.m., followed 44 min later by 50 mg (0.014 mg/kg) butorphanol i.v. This immobilization was rated only as fair.

Yohimbine (Spectrum Quality Products, New Brunswick, NJ 08901 USA; 60-72µg/kg i.v.) was used to reverse the effects of xylazine in three immobilizations. Naloxone (2.8 µg/kg i.v.) was used in the first immobilization of the male elephant to reverse the effects of the butorphanol. It was the author's impression that both drugs, particularly the naloxone, decreased the duration of sedation.

Discussion

The azaperone dosages used at the Knoxville Zoo are similar but slightly less than those reported by others for African elephants. Page reviewed MedArks records and reported on sedations and tranquilizations rated good or excellent, which had normal recoveries, and without complications.² Using these criteria in African elephants, he found a mean azaperone dosage (±SD) of 0.1 ± 0.030 mg/kg (range: 0.06-0.150 mg/kg; n = 13). Raath suggests a dosage of 0.1 mg/kg i.m. for tranquilization of African elephants for transportation and discusses use of haloperidol in combination with azaperone for large or wild young elephants.³ Kock et al. recommends 120-760 mg, 120 mg, and 3-120 mg (total doses) of azaperone for adult, juvenile-adult, and baby-juvenile elephants (species and route of administration not stated), respectively.¹ Generally, all these dosages are much greater than those describe by Schmidt for standing sedation of Asian elephants (0.03 mg/kg azaperone; range: 0.017-0.046 mg/kg).

The xylazine dosages used at the Knoxville Zoo tend to be less than those reported by Page.² For sedations using xylazine alone, Page identified a mean dosage of 0.22 ± 0.13 (range: 0.11-0.55 mg/kg; n = 10). He describes use of a combination of xylazine, butorphanol, and ketamine but does not state route of administration, if these animals remained standing, nor how many procedures were performed. For xylazine sedation, Kock et al. suggests total doses of 700 mg, 200-600 mg, and 20-160 mg, for adults, juveniles and babies (species and route not stated), respectively.¹

Conclusions

In summary, it is the author's preference to use i.m. azaperone at total doses of 280-320 mg per even-tempered adult African elephant (approximate dosages of 0.08-0.09 mg/kg) for minor medical procedures, such as venipuncture or trunk wash-cultures. For aggressive animals or more noxious procedures, the author prefers i.m. xylazine at total doses of 700-1000 mg/adult animal (approximate dosages of 0.2-0.3 mg/kg) followed by intravenous butorphanol at doses of 50-180 mg/adult elephant (approximate dosages of 0.01-0.03 mg/kg), depending on size and temperament.

Table 1. Summary of approximate dosages and ratings of standing sedation and tranquilization of captive African elephants (Loxodonta africana).

a. Actual weights were not available on the animals, so all dosages are approximations.

References

1.  Kock RA, P Morkel, MD Kock. 1993. Current immobilization procedures used in elephants. In: Fowler, M.E. (ed.). Zoo and Wildlife Medicine, Current Therapy 3. W.B. Saunders Co., Philadelphia, Pennsylvania. Pp. 436-441.

2.  Page CD. 1994.In: Mikota, S.K., E.L. Sargent, and G.S. Ranglack (eds.). Medical Management of the Elephant. Indira Publishing House, West Bloomfield, Michigan. Pp.41-49.

3.  Raath JP. 1993. Chemical capture of the African elephant Loxodonta africana. In: McKenzie, A.A. (ed.). The Capture and Care Manual Capture, Care, Accommodation and Transportation of Wild African Animals. Wildlife Decision Support Services and The South African Veterinary Foundation, Pretoria. Pp. 484-493.

4.  Schmidt DL, JP Bradford, DA Hardy. 1996. Azaperone for standing sedation in Asian elephants (Elephas maximus). Proc. Am. Assoc. Zoo Vet. Puerto Vallerta, Mexico. Pp. 48-51.