Reimmunization Increases Contraceptive Effectiveness of GonaCon-Equine Vaccine in Free-Ranging Horses (Equus caballus): Limitations and Side Effects

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Reimmunization Increases Contraceptive Effectiveness of GonaCon-Equine Vaccine in Free-Ranging Horses (Equus caballus): Limitations and Side Effects Investigators: D. Baker 1, J. Powers 2, J.

1 Reimmunization Increases Contraceptive Effectiveness of GonaCon-Equine Vaccine in Free-Ranging Horses (Equus caballus): Limitations and Side Effects Investigators: D. Baker 1, J. Powers 2, J. Ransom 2, B. McCann 2, M. Oehler 2, J.Bruemmer 1, N. Galloway 2, D. Eckery 3, and T. Nett 1 1 Colorado State University, 2 National Park Service, 3 United States Department of Agriculture/ Animal and Plant Health Inspection Service

2 Study Area Southwestern North Dakota 46,000 acres fenced 130 horses 15 bands Historical demonstration herd

3 Theodore Roosevelt National Park Diverse Badlands typography Multiple wild ungulate species Abundant year-round forage Few predators

4 Management Problems: Overabundant Feral Horses Alter native plant communities Compete for limited forage resources Limited methods of population control United States Geological Survey

GnRH Vaccine (GonaCon-Equine) Reproductive Pathway Vaccine Hypothalamus Brain GnRH antibodies Ovary Ovum BLOCK GnRH Anterior Pituitary FSH LH Testis testosterone Gonads spermatogenesis BLOCK

5 GnRH Vaccine (GonaCon-Equine) Reproductive Pathway Vaccine Hypothalamus Brain GnRH antibodies Ovary Ovum BLOCK GnRH Anterior Pituitary FSH LH Testis testosterone Gonads spermatogenesis BLOCK ovulation estrogen/progesterone Inhibits ovulation and spermatogenesis Tested in many wild ungulate species Single treatment multiple years Safe EPA approved for feral horses, burros, and white-tailed deer

6 Objective To determine the effective duration and safety of a single vaccination and subsequent reimmunization with GonaCon-Equine in free-ranging horses

7 Methods: Animal Capturing and Handling

Experimental Horses 2009 (October): Primary Vaccination 29 GonaCon-Equine; 28 saline Similar in age, pregnancy status, stage of gestation, body condition, general health 2013 (September):

8 Experimental Horses 2009 (October): Primary Vaccination 29 GonaCon-Equine; 28 saline Similar in age, pregnancy status, stage of gestation, body condition, general health 2013 (September): Reimmunization 4 years post-primary Same mares recaptured and processed 25 GonaCon-Equine; 26 saline control Similar in pregnancy status, stage of gestation, body condition, and general health

Methods: Reproduction Foaling Proportions:

Vaccine effectiveness as the proportionate

9 Methods: Reproduction Foaling Proportions: Weekly observations of each study mare for presence or absence of a foal during March 1- August 1 each year Vaccine Effectiveness: Vaccine effectiveness as the proportionate reduction in foaling between control and treated mares.

10 Scan sampling time budgets All-occurrence social behaviors Ransom et al Methods: Behavior

11 Methods: Injection Site Reactions

12 Results: Reproduction

13 Results: Behavior No difference in maintenance behaviors (feeding, resting, travelling) No difference in social behaviors (herding, agonism, reproductive)

14 Results: Injection Site Reactions ~70% swelling or abscess following a single vaccination ~50% similar reactions following reimmunization No evidence of lameness, or depression, was observed for any treated mare following either vaccination

Conclusions: GonaCon-Equine was demonstrated to be safe but minimally effective (30%) and short duration (2 yrs.) when administered as a single inoculation to free-ranging horses.

15 Conclusions: GonaCon-Equine was demonstrated to be safe but minimally effective (30%) and short duration (2 yrs.) when administered as a single inoculation to free-ranging horses. However, when the primary vaccination was followed by a booster immunization, four years later, it was shown to be highly effective (90%) and long-term (4 yrs.) without significant adverse side effects. Management implications?

16 Future Research: 1. Continue to monitor duration of effectiveness, return to fertility, and effects on the phenology of parturition 2. Continue to monitor the long-term side-effects of reimmunization on treated females 3. Develop and test remote dart delivery of vaccine 4. Determine the most effective reimmunization schedule 5. Conduct population level studies

17 Reimmunization Schedule? Objective: Determine the optimum interval between the primary and booster immunization. Hypothesis: Decreasing the interval between the primary and booster immunization will decrease effective duration of GonaCon-Equine. Experimental design: Years after 1 st vaccination: Sample size: Requires remote dart delivery of GonaCon-Equine Measure: foaling proportions, injection site reactions, body condition

18 Acknowledgements: National Park Service Animal Reproduction and Biotechnology Laboratory, Colorado State University Bureau of Land Management Morris Animal Foundation National Wildlife Research Center Deb Carson Photography Field Research Technicians and Volunteers the unsung heroes

19 Questions?

Delivery of GonaCon -Equine to Feral Horses (Equus caballus) Using Prototype Syringe Darts

National Park Service U.S. Department of the Interior Theodore Roosevelt National Park (THRO) Delivery of GonaCon -Equine to Feral Horses (Equus caballus) Using Prototype Syringe Darts B. McCann 1, D.