APHIS Factsheet

Wildlife Services January 2008

GonaConTM–Birth 

Control for Deer: 

Questions and Answers 

Q. What is GonaConTM?

A. GonaCon TM is a new gonadotropin-releasing 

hormone (GnRH) immunocontraceptive vaccine developed by scientists at the U.S. Department of Agriculture’s (USDA) Wildlife Services’ (WS) National Wildlife 

Research Center (NWRC). Presently, applications of 

GnRH are being researched in controlled field studies 

for potential use as a wildlife management tool. 

Q. How does GonaCon TM work?

A. The single-shot, multiyear vaccine stimulates the 

production of antibodies that bind to GnRH, a hormone in an animal’s body that signals the production 

of sex hormones (e.g., estrogen, progesterone, and 

testosterone). By binding to GnRH, the antibodies 

reduce GnRH’s ability to stimulate the release of 

these sex hormones. All sexual activity is decreased, 

and animals remain in a nonreproductive state as long 

as a sufficient level of antibody activity is present.

Q. How does GonaCon TM stimulate the production 

of antibodies?

A. GonaCon TM causes an animal’s body to make antibodies against its own GnRH. To do this, WS scientists synthesize and hook GnRH to a foreign protein. 

This material looks like a large, new molecule that the 

animal’s immune system has never encountered. As 

a result, when it is injected into the animal’s body, the 

body’s immune response neutralizes the hormone’s 

function, resulting in infertility.

Q. What are the health effects associated with 

GonaCon TM?

A. The health effects associated with GonaCon TM

are minimal. Vaccinated animals showed a decrease 

in sexual activity and breeding behavior. In field and 

pen studies, animals showed little to no visual evidence of inflammation at injection sites, and blood 

chemistry was similar among treatment and control 

groups. However, in some necropsied animals, 

granulomas were present at injection sites. 

Development of granulomas is a common side effect 

in vaccines with adjuvants, which are compounds 

used in many human and livestock vaccines to 

enhance a vaccine’s effectiveness. 

Q. Are there any dangers or secondary hazards to 

humans or other animals that eat meat from 

vaccinated deer?

A. There is no known danger associated to humans 

or wildlife from eating deer that have been vaccinated 

with GonaCon TM . In 2005, the U.S. Food and Drug 

Administration (FDA) informed APHIS that whitetailed deer vaccinated with GonaCon TM do not raise a 

human food safety concern. As with other vaccines, 

such as those used with livestock, both the vaccine 

and the antibodies produced are proteins. Once 

ingested, they are broken down by stomach acids and 

enzymes. In 2003, the FDA approved the slaughter 

of experimentally vaccinated pigs with GonaCon TM. 

Similar injectable hormone-altering products are used 

routinely in livestock applications. 

Q. How long does GonaCon TM last?

A. It depends upon the individual animal and its 

response to the vaccine. Long-term field efficacy data 

currently does not exist. However, in pen studies, a 

single-shot of GonaCon TM has successfully kept 4 out 

of 5 female deer infertile for 5 years. A second shot 

given the same year or in subsequent years can significantly increase effectiveness, potentially rendering 

deer infertile for life.

Q. Can GonaConTM be used with other wildlife 

species?

A. In addition to white-tailed deer, GonaCon TM has 

proven effective for use with other wildlife species, 

including California ground squirrels, Norway rats, 

feral cats and dogs, domestic and feral swine, wild 

horses, and elk. Since registering the contraceptive is 

time consuming and costly, WS has decided to focus 

registration efforts on use for female white-tailed deer. 

Future research will likely be directed toward registering GonaCon TM for use with other wildlife species.

Q. What are the benefits of GonaCon TM?

A. Because it is a single-shot, multiyear vaccine, 

GonaCon TM may be a practical management tool. 

Deer may need to be injected only once to become 

infertile for up to 5 years. A boost injection could 

increase effectiveness to almost 100 percent and 

increase longevity of the contraceptive effect. The 

vaccine can be used in urban and residential areas, 

where other management methods, such as hunting, 

are not an option. 

Q. What are the limitations of GonaCon TM?

A. GonaCon TM must be injected into the muscle or 
United States Department of Agriculture • Animal and Plant Health Inspection Service • Safeguarding American Agriculture

tissue of each animal. Eventually, WS scientists hope 

to produce an oral GnRH vaccine bait that will be 

attractive to deer but not other animals.

Q. How much does GonaCon TM cost?

A. The vaccine itself only costs $2–$10 per dose. The 

main cost of using GonaCon TM is associated with the 

time and money required to capture and vaccinate the 

deer. This cost can be several hundred dollars per 

deer depending upon many factors, such as how many 

deer need to be captured and whether the deer are 

easy or difficult to catch.

Q. How does GonaCon TM differ from porcine zona 

pellucida (PZP)?

A. PZP, another immunocontraceptive vaccine, has 

been used to sterilize dogs, coyotes, burros, wild 

horses, and white-tailed deer temporarily. The PZP 

vaccine, also known as SpayVacTM, causes multiple 

estrus cycles in female deer. GonaCon TM, however, 

prevents female deer from entering estrus.

Q. Is GonaCon TM currently available to Federal, 

State, and local wildlife management agencies?

A. No. Once registered, GonaCon TM will be under 

the authority of the Environmental Protection Agency 

(EPA). The GonaCon TM studies underway in Maryland, 

New Jersey, and Pennsylvania are being conducted 

as part of EPA’s approval process. NWRC hopes to 

submit a registration application to EPA in early 2008 

and anticipates a product registration approximately 18 

months after submittal. NWRC is currently seeking a 

private-sector partner to take the vaccine to market.

Q. Who will be allowed to use GonaCon TM?

A. GonaCon TM will be registered as a “Restricted Use” 

product. Although final label language has not been 

negotiated with EPA, NWRC anticipates the product will 

be labeled for use by USDA–APHIS Wildlife Services 

or State wildlife management personnel or persons 

working under their authority. GonaCon TM users will 

need to follow State authorization processes. 

Q. Will GonaCon TM eliminate the need for hunting 

to control deer overpopulation?

A. No. Contraception alone cannot reduce overabundant deer populations to healthy levels. GonaCon TM

is a tool to be used in conjunction with other wildlife 

management methods.

Q. What studies are currently being done with 

GonaCon TM?

A. A field study near Silver Spring, MD, provided additional data on the efficacy of the vaccine on white-tailed 

deer. At a fenced military facility, 28 adult does were 

captured in the summer of 2004, equipped with 

eartags and radiotelemetry transmitters, and injected 

with GonaCon TM. The reproductive behavior and 

reaction of these does were monitored for 2 years and 

compared with those of 15 unvaccinated adult does that 

inhabit an adjacent, enclosed parcel of similar habitat. 

Data show the vaccine to be 88 percent effective the 

first year and 47 percent effective the second year in 

treated deer.

 In July 2005, a similar field study involving another 

28 deer was started in Morris County, NJ, that showed 

67 percent effectiveness the first year and 48 percent 

effectiveness the second year. Results from these 

studies will be submitted to the EPA during the 

registration process for GonaCon TM.

 WS scientists collaborated with Pennsylvania 

State University to conduct studies required by EPA on 

the toxicity and safety of GonaCon TM in captive deer. 

Responses of treated and control groups of deer were 

compared via blood and tissue analyses. Data showed 

no differences between treatment and control groups. 

Q. What does WS hope to accomplish with these 

studies?

A. Data from field and pen studies will aid in the final 

EPA process for approving GonaCon TM as a 

contraceptive for use in wildlife and feral animals. 

Q. What other agencies or organizations are 

involved in these studies?

A. USDA’s WS is working with the following agencies 

and organizations to develop and test GonaCon TM:

• Pennsylvania State University

• U.S. General Services Administration

• U.S. Department of Defense

• USDA’s Veterinary Services

Q. What is the NWRC mission?

A. The NWRC is the research arm of USDA’s WS program, a nonregulatory program that provides Federal 

leadership in managing conflicts with wildlife. NWRC 

applies scientific expertise to the development of practical methods to resolve human-wildlife conflicts and 

maintain the quality of the environments shared with 

wildlife. 

Q. How do I obtain more information on this 

subject?

A. For more information on GonaCon TM and WS’ 

National Wildlife Research Center, please go to 

http://www.aphis.usda.gov/wildlife_damage/nwrc/ on 

the Web.

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