Cervus elaphus, known as elk or wapiti, is the most widely distributed cervid in the world. Wapiti were historically abundant in the southern Appalachians but are thought to have been eliminated from the region by the mid-1800s. Recently, there have been several efforts to reintroduce this species to the southeastern US, largely due to the conservation efforts of the Rocky Mountain Elk Foundation. Beginning in 1999, the Wildlife Management Department, Great Smoky Mountain National Park (GSMNP) and faculty of the Department of Comparative Medicine began interacting on veterinary aspects of an experimental release of elk into the GSMNP, scheduled to occur in 2001. Through this relationship, elk health and management concerns were intercalated into the comprehensive experimental release plan.
Initial discussions focused on the important diseases of elk,1 with emphasis on diseases not currently identified in the GSMNP or region. Diseases and parasites of concern included:
- Bovine tuberculosis (TB)
- Chronic wasting disease (CWD)
- Bovine brucellosis
- Parelaphostrongylus tenuis
- Echinococcus granulosis
- Fascioloides magna
- Dermacenter albipictus
- Psoroptes spp.
- Otobius megnini
The release plan addressed each pathogen of concern, via testing, treatment, or source herd health history.
A free-ranging enclosed herd of elk at the US Forest Service’s Land Between the Lakes National Recreational Area (LBL), Kentucky, was selected as the source of the release animals. This herd had been established in 1996 and 1997 with animals from Elk Island National Park, Alberta, Canada. The LBL herd has had no cases of TB, CWD, or brucellosis. The Elk Island National Park herd has been certified TB and brucellosis free since 1972 and there is no history of CWD in that herd. All elk were tested for TB and brucellosis prior to transfer from LBL. Each elk was treated for parasites with ivermectin (Merial, Iselin, NJ 08830 USA) and cloruslon (Merial) while held at LBL prior to transportation to GSMNP. Chronic wasting disease and Echinococcus granulosis infections remain concerns regarding the animals released in GSMNP. Any elk that dies or is euthanatized will be removed from the study site and necropsied. Carcasses will be specifically screened for CWD and E. graunulosis infection.
Development of chemical capture techniques was the other major area of veterinary involvement. Carfentanil citrate was chosen as the principal immobilization agent; however, ultra-potent opioids had not been previously used by GSMNP staff. The primary topics veterinarians were asked to address were immobilization regimens and personnel safety. Following an initial immobilization trial, the following regimens were utilized: adults (body weight range=124 to 269 kg, n=19): 1.5 mg carfentanil (Wildlife Pharmaceuticals, Inc, Fort Collins, CO 80524 USA) and 45 mg xylazine (Miles Inc., Animal Health Products, Shawnee Mission, KS 66201 USA) and 0.05 ml either saline or hyaluronidase (Sigma Chemical, St. Louis, MO 63178 USA; approx. 150 IU) suspended in sterile water, IM; and juveniles (body weight range=91 to 183 kg , n=7): 0.9 mg carfentanil citrate, 30 mg xylazine, and 0.05 ml of either saline or hyaluronidase in sterile water, IM. Agents were delivered by 1 ml darts and powder-charge rifle (Pneu-dart, Inc., Williamsport, PA 17703 USA). Twenty-two immobilizations were considered good to excellent (minimal running after darting, first effect within 4.5 min, lateral recumbency within 8.5 min of darting). One adult and one juvenile required a second dart (all darts contained the same amount as initial darts) to be captured and one adult required three darts to be immobilized. Mean (±SD) time to first effect was 2.7±1.0 min and mean time to lateral recumbency was 3.9±1.8 min, for immobilizations rated good or excellent. All elk were reversed with naltrexone (Wildlife Pharmaceuticals; 150 and 100 mg, for adults and juveniles, respectively; half the dose IV and half SC) and IV yohimbine (Sigma Chemical; 30 mg and 20 mg, for adults and juveniles, respectively). All animals recovered from immobilization satisfactorily and there were no mortalities associated with the chemical restraint.
As of 2 May 2001, all elk are doing well and there have been no mortalities.
The authors thank Mr. Steve Bloemer, Mr. Scott Ray, Dr. Loren Wagoner, and the other staff of the Land Between the Lakes National Recreation Area, Golden Pond, Kentucky for their assistance in this effort.
1. Nettles, V.F., and J.L. Corn. 1998. Model health protocol for importation of wild elk (Cervus elaphus) for restoration. Southeastern Cooperative Wildlife Disease Study, College of Veterinary Medicine, The University of Georgia, Athens, GA, p.22.