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Levonorgestrel implants as a contraceptive in captive white-tailed deer
L M White1, R J Warren, R A Fayrer-Hosken
1School of Forest Resources, University of Georgia, Athens 30602.
Journal of Wildlife Diseases
|April 1, 1994
Summary
Levonorgestrel (LNG) implants were tested for contraception in white-tailed deer. Despite achieving measurable serum concentrations, LNG implants did not effectively prevent pregnancy in captive deer, leading to a recommendation against their use.
Area of Science:
- Wildlife reproductive science
- Endocrinology
- Veterinary pharmacology
Background:
- Contraception in wildlife is crucial for managing captive populations and mitigating human-wildlife conflict.
- Levonorgestrel (LNG) is a progestin hormone used in human contraception, but its efficacy in non-human species requires investigation.
Purpose of the Study:
- To evaluate the efficacy of Silastic implants containing levonorgestrel (LNG) as a contraceptive method in captive white-tailed deer (Odocoileus virginianus).
Main Methods:
- Six adult and six fawn female white-tailed deer received either six or nine Silastic implants containing 36 mg of LNG each.
- Serum LNG concentrations were measured using radioimmunoassay for 5 months post-implantation to determine the release profile.
- Estrous cyclicity and pregnancy rates were monitored in implanted deer over one to two years.
Main Results:
- Serum LNG concentrations increased significantly within 3 days post-implantation and remained stable for 5 months.
- Higher LNG concentrations were observed in deer receiving nine implants compared to six, but levels did not differ between adults and fawns.
- Despite LNG administration, 50% of adult females and all monitored yearlings and adults became pregnant within one to two years.
Conclusions:
- Levonorgestrel implants did not demonstrate contraceptive efficacy in captive white-tailed deer.
- The study does not recommend the use of LNG implants for contraception in this species.
- Further research may be needed to explore alternative contraceptive strategies for white-tailed deer.