Immunocontraception is non-hormonal form of contraception, based on the same principles as disease prevention through vaccination. An immunocontraceptive causes the production of antibodies against some essential element of the reproductive process, thus preventing pregnancy.

There are a variety of immunocontraceptive vaccines under development including vaccines against brain reproductive hormones such as gonadotropin-releasing hormone (GnRH); pituitary hormones such as luteinizing hormone (LH) and follicle-stimulating hormones (FSH); and vaccines against steroid reproductive hormones such as estrogen and progesterone. Thus far PZP has had the widest application to wildlife.

From: Frequently Asked Questions on IMMUNOCONTRACEPTION, Wildlife Fertility Control



  • PZP is a controlled substance regulated by the EPA
  • PZP innoculation means venison not suitable for human consumption.
  • PZP is not approved for use in Michigan
  • In March 2014, a 5-year clinical trial began in Hastings-on-Hudson, NY to test the efficacy of PZP on free-moving deer. Clinical trial must been completed 2019, and the results evaluated.
    • First year of Hastings trial cost $10,000 with only one doe treated (out of a target 60); Penn deer guide says ($500-$1300 per deer).
    • Second year of trial expected to cost the same.
  • MDNR and USDA NWRC do not regard immuno-contraception a viable way to reduce deer populations in free-moving populations.
  • Does have to be innoculated (darted) repeatedly for PZP to be effective; treated animals must be marked
  • Only effective up to 4 yrs– does reproduce for up to 15 years
  • Darts that might fall out or miss may be a safety hazard for other wildlife, pets, and humans.
  • Does continue to have a monthly estrus cycle, attracting bucks from miles away.
  • Does not address existing deer problems

Focusing on fertility control delays implementation of effective management programs (MDNR).

Note on Hastings-on-Hudson experience:

The Hastings-on-Hudson experience is important because HoH appears to be THE site studying the use of PZP with free-roaming deer, and PZP is, along with surgical sterilization, the non-lethal method of choice for the Humane Society of the US. It will take five years to come to conclusion about the effectiveness of PZP in a non-isolated setting, but year one does not seem to have been a success.
I’d like to note that the Humane Society studied PZP on Fire Island (off Long Island, NY) and cites that experience as a success for deer contraception. However, there are still too many deer on Fire Island and the National Park Service has now rejected PZP as a control method in the management plan for Fire Island now being developed. As reported on August 28, 2014 in Newsday.
“The Humane Society worked with the park service on a 15-year study of an immunocontraceptive vaccine on the deer population, and Griffin said the vaccine cut the deer population on Fire Island in half from 1995 to 2009. ((but))
“The park service said the vaccine used in the Humane Society study is unacceptable because of the short duration of a dose, the lack of federal approval for the vaccine, and breeding behavior in vaccinated does.”


  • Fort Thomas considering deer contraceptive program to control population, Fox19, NOv 22, 2017Around 10 years ago, the city introduced a bow and arrow deer hunting season to try to control the growing population but it hasn’t been working, so now are considering a deer birth control program. She said the injection lasts two years and the darts would cost around $75 a piece.**
    **Beware of reporters who do not do thorough research.
    Actual cost “Clifton’s program cost $975.61 per deer
  • Voters to decide fate of deer park, News-Review, Nov 3, 2016From 2013 to 2015, the city used the contraceptive program as a way of slowing the population growth, but it did not reduce the size of the herd. A yes vote would mean a vote to close the deer park and passing a law that would restrict and prohibit wild animal enclosures within the city.
  • GonaCon™ New GnRH Single Shot, USDA, July 15, 2015NWRC scientists are hopeful that the GnRH vaccine will soon be approved for use for wildlife fertility control. GnRH vaccines have an advantage over PZP because they prevent eggs from being released from the ovaries, thereby eliminating estrus and some undesirable behaviors (e.g., bucks chasing does across roads) associated with it.
  • Birth Control for Bambi, UnDark, April 15, 2016Working swiftly, Pereira clips a palm-sized yellow tag, stamped with the number 41, onto the doe’s right ear. Pauli carefully removes the dart and cleans the small wound it has gouged in 41’s hindquarters, then draws a blood sample, causing the doe to kick fitfully. Finally, it’s time for the pièce de résistance: A long needle containing a milky emulsion, which Pauli plunges into the deer’s tawny flank. This is the PZP — or porcine zona pellucida — a birth control vaccine.
    Over the past century, humans have created prime conditions for Odocoileus virginianus. We’ve wiped out their predators, enhanced their numbers for hunters, and planted trees and gardens on which they love to feed. With a population once as low as 500,000, the number of white-tailed deer in the United States is now more than 20 million. The unchecked abundance has produced ecological chaos.

    Hastings-on-Hudson, a Westchester County village 15 miles north of New York City, is no stranger to these perils. The town averages more than 100 cases of Lyme, 20 deer-related car accidents, and a half-million dollars in vegetation damage each year.

    Because immunocontraception, like tubal ligation, doesn’t prevent female deer from entering heat, Curtis is skeptical that PZP will work in open systems like Hastings. Instead, he recommends ovariectomies, which shut down hormonal cycles altogether. The phrase “rats with hooves” is not uncommon — they’ve embraced the project, perhaps out of desperation. Fluorescent flags granting biologists permission to treat deer on private property flutter on neighborhood lawns. Some homeowners have let Pauli use their garages and porches as makeshift hunting blinds. High school students are studying tree diversity in town woodlands to see whether saplings will bounce back during the experiment. “This project takes community effort as much as it takes our fieldwork,” Pereira said.

    The deer have not proved equally cooperative. White-tails are wily by nature, and they turn understandably skittish around gun-packing strangers; many also linger near schools, where the team can’t dart. After three years, the biologists have vaccinated a total of 48 deer, likely a bit less than half the population; this fall, they’ll return to Hastings to administer booster shots to the does treated in 2014, identifiable by their numbered ear-tags.
  • As I See It: Science tackles deer problem, Alan Rutberg, The Telegram, Jan 10, 2016Because it’s a natural protein vaccine, the contraceptive does not taint the meat; it’s destroyed in digestion. But confusion with steroid contraceptives has allowed the tainted meat argument to sit on the shelves long past its expiration date.
      Issues identified with PZP:

    • – It does not stop eggs from being released from the ovaries, and so does have continuing multiple estrus cycles.
    • – Cornell study found deer numbers did not decrease because does in heat attract bucks from neighboring areas and so adult buck immigration becomes a factor

  • Mark Blazis: Contraception won’t shrink deer population in Blue Hills,, Dec 17, 2015 At Fripp Island, the drug worked to a degree. After 5 years, it reduced the herd by half, which at first sounds very impressive, but while that accomplishment might appear to be a cause for celebration, Charles Ruth, the man in charge of South Carolina deer management, with whom I spoke at length this week, had less enthusiastic appreciation for the fertility treatment and strategy. He sees it valuable only in extremely small places that are very isolated.
  • Hastings deer control project looks for long-term results, Lohud, Oct 15, 2015 Deer are still very much at home in the village, chomping through vegetable gardens and munching on azaleas — but there are some early signs that there might be fewer of them.

    The community is getting ready to start the third year of a five-year experiment to reduce its deer population through the use of birth control on local does. Researchers hope to prevent the births of at least 27 deer this year and another 27 the following year. There are some 100 to 120 deer in the 2.9-square-mile village. “Right now, more deer are being born every year than are dying,” Griffin said. “The goal is to have a lower birth rate than attrition rate.”
  • Single Injection Could Sterilize Large Invasive Species Populations, BioScience Technology, Oct 7, 2015Scientists from the California Institute of Technology have tested the injection on a group of mice. The shot contained a small amount of DNA that can make muscle cells create specialized antibodies to attack GnRH. It took two months for the mice’s bodies to produce enough antibodies to render them completely infertile (for 10).
  • Vectored antibody gene delivery mediates long-term contraception, Current Biology, October 5, 2015Development of non-surgical methods of long-term or permanent contraception remains a challenge. Towards this objective, we show that intramuscular injection of a replication-incompetent, recombinant adeno-associated virus (rAAV) designed to express an antibody that binds gonadotropin-releasing hormone (GnRH), a master regulator of reproduction in vertebrates, results in long-term infertility in male and female mice. Female mice are also rendered infertile through rAAV-dependent expression of an antibody that binds to the zona pellucida (ZP), a glycoprotein matrix that surrounds the egg and functions as a sperm-binding site.
  • Sterilization/Contraception, presentation to Mt. Lebanon, June 22, 2015, Dr Anthony DeNicola, Founder/President, White Buffalo Inc.Powerpoint presentation on costs/issues, status of response to previous PGC questions and other deer management issues.
  • What PZP Pushers Don’t Want You To Know, ActionLine, Spring 2015It didn’t surprise Friends of Animals that a lot of the research touting the advantages of PZP has been conducted by those with a vested interest in it— the Humane Society of the United States, which has to approve the use of PZP on wild horse herds—and Jay Kirkpatrick, HSUS consultant for contraception and director of the Science and Conservation Center in Billings, Montana, which produces the active ingredient in PZP.
  • Hastings to Begin Deer ‘Darting’ Project Feb. 2,, Jan 25, 2015Hastings-on-Hudson will begin conducting its second Deer Immunocontraception Study on Feb. 2, Mayor Peter Swiderski announced in an email to residents Sunday.
  • Cornell University’s Expensive “Birth Control for Deer” Program Proves Effectiveness of Hunting in Wildlife Management, AllOutdoor, Oct 23, 2014The failure of Cornell University’s “birth control for deer” experiment is an example of how traditional hunting practices are more sound than ideologically driven wildlife management decisions.
    A total of 77 does were captured and sterilized by tubal ligation at a cost of about $1,200 per deer. While tubal ligation is an effective birth control method for humans or captive animals, it doesn’t work so well on wild animals. Why? Because they move. In fact, the sterilization had an unintended consequence: Because the does could not get pregnant, they entered heat month after month, and this brought more bucks onto the campus.
  • DEC green-lights plan to inject deer with birth control, Rivertown Enterprise, Jan 3, 2014The DEC permit gives permission to tranquilize, tag and inject the deer with PZP, a widely used animal immunocontraceptive, to determine whether the drug can reduce the deer population over a five-year period. The actual licensee is Dr. Allen Rutberg, director of the Center for Animals and Public Policy at the Cummins School of Veterinary Medicine at Tufts University in Grafton, Mass. Rutberg has been affiliated with the Humane Society of the United States on deer vaccination projects since 1991, and has designed the protocols for the program to be used in Hastings. This will be the first time Rutberg will be conducting deer contraception in a dense suburban area.
  • National Park Service considers ways to reduce Fire Island deer herd, Newsweek, August 28, 2014
  • East Hampton Village Preservation Society Donates $100K To Deer Spaying Program,, Sept 5, 2014
  • City uses birth control to limit nuisance deer herd, USAToday, March 18, 2015To reduce those numbers, Hastings is trying to keep its female deer from getting pregnant by injecting them with a contraceptive vaccine. That has researchers from the Humane Society of the United States cruising the village’s streets.
    The Teatown Lake Reservation in Yorktown recently enlisted specially trained biologists to shoot 11 deer. Some Westchester County parks and the Mianus River Gorge Preserve have used bow hunters to reduce their deer numbers.
    Researchers hope to treat 60 deer this year and during the next two winters, and to continue to monitor them. Captured does — tranquilized first with a drug-filled dart — will have a numbered ear tag attached, blood drawn for a pregnancy test and an initial vaccine dose. Known as PZP, the vaccine uses a doe’s immune system to stop her eggs from being fertilized.
    But after about a week of looking for deer, Naugle and Grams had tagged and treated just one. They can fire at deer no more than 20 yards away with their air-powered rifles, and they are still learning where the animals spend their days.
  • The Deer Wars Part 2: Mad Science, Outdoor Life
  • Wild Contraception: The Pests, Popular Science, June 23, 2014One reason that other places haven’t jumped on the PZP bandwagon is that Fire and Fripp Islands have a very particular advantage: they are home to isolated populations—the deer are stuck there and can’t leave.
  • Deer: Contraception, City of Bloomington
  • Deer: Contraception, City of BloomingtonEFFICACY: As a stand-alone management strategy, contraception does not reduce overabundant deer populations.
  • Porcine Zona Pellucida Immunocontraception in Mammals, USDA APHIS, Jan 30, 2014
  • IDNR’s Policy on Deer Contraception, Deer Relocation, and Tick Control Using the 4-Poster Deer Treatment Bait Station, City of Bloomington, IN, 2012
  • Not tonight deer: A new birth control vaccine helps reduce urban deer damage, ACS: Chemistry for Life, Aug 31, 2011
  • Md. approves use of deer birth control, Washington Post, May 5, 2011Maryland has become the first state to approve the use of Gonacon, a deer birth control product, but the state’s director of wildlife said Friday he can’t imagine it ever being used in what he termed the open landscape.

    “This is the only immuno-contraceptive for deer that has federal approval,” said Paul Peditto, director of the Wildlife and Heritage Service. “It was developed by the U.S. Department of Agriculture and is registered with the Environmental Protection Agency.

    Peditto said the manpower and expense of applying the birth control chemical will limit its use. “It will cost up to $1,000 to apply it to a deer,” Peditto said. The deer must first be shot via dart gun to tranquilize it before Gonacon can be injected. EPA requires that the deer be tagged so that it can be identified as having been treated. Another tag will state that the meat of the animal should not be consumed by humans.

  • Survival analysis and computer simulations of lethal and contraceptive management strategies for urban deer, MARRETT D. GRUND, Human–Wildlife Interactions, Spring 2011I recommend removing 20% of adult females from an urban deer population with similar demographic parameters to stabilize population growth and about 40% of the female population to decrease population numbers. Similar to conclusions made by Swihart and DeNicola (1995), I conclude that almost all adult females in a healthy population of deer need to be administered contraceptives for population growth to decrease.
  • PZP Study Raises Concerns for Use on Wild Horses , Straight from the Horse’s Heart- blog, Oct 29,2010
  • The Princeton University researchers studied the foaling data, and found that since the contraception programme began in January 2000, foaling has occurred over a significantly broader range than it had before the program.

  • Porcine Zona Pellucida Immunocontraception in Mammals, US APHIS, March 23, 2010The PZP vaccine is a highly effective contraceptive, but unfortunately it causes multiple estrous cycles in female deer. These multiple cycles and the recurrent sexual activity (and deer movements) associated with them may increase deer-vehicle collisions and other deer-human conflicts. The PZP vaccine does not seem to cause multiple estrous cycles in other species on which it has been tested, and it may prove to be a highly useful infertility agent for other wildlife.
  • Contraceptive efficacy of a novel intrauterine device (IUD) in white-tailed deer., Anim Reprod Sci. 2010 Feb, 117(3-4):261-5 (Abstract only) Intrauterine devices show potential as a tool for small-scale deer population management via non-steroidal reproductive inhibition.
  • Factors contributing to the success of a single-shot, multi year PZP immunocontraceptive vaccine for white-tailed deer, Digital Commoms, 1-4-2009PZP-treated deer had multiple estrous cycles every year of the 5-year study, with the multi-cycling ceasing only when they became pregnant. The number of estrus events for all PZP-treated deer ranged from 1.5 to 3.0 per season, with an average breeding season length of 150 days. This compares to 0.2 to 0.5 estrus events for does in the untreated herd and an average breeding period of 42 days per season. The 4 does in IVT-PZP Group 2 averaged 1.75 estrus events in year seven of the trial, demonstrating that cycling was still occurring, although none of the does had fawns.
  • Wildlife Contraception, University of Wisconsin, Contraception, July 29, 2008
    Similar limitations apply to deer in North America. Although deer control remains a goal in dozens of states, contraception will never keep the lid on 25 million deer. Bullets can whittle down deer numbers in a way that darts can’t, and people are lining up to pay license fees for the privilege of doing it. “It’s much cheaper,” concludes Turner, “to put a bullet in a deer than it is to contracept it.”

  • Pathophysiology of white-tailed deer vaccinated with porcine zona pellucida immunocontraceptive, Vaccine, 2007
  • Contraception & deer: the Irondequoit report, William F. Porter and H. Brian Underwood, Roosevelt Wild Life Station, State University of New York College of Environmental Science and Forestry, 2001Irondequoit was the first study in an environment typical of most suburban communities facing the dilemmas of deer management. At the outset of the study no one had direct experience with using contraception to control growth in a free–ranging deer population. Earlier work at Front Royale had focused on behavioral impacts of contraception.

    Other trials at Fire Island were not applicable because of the unique nature of the deer population and the geography of the island. Studies at the National Institute of Standards and Technology, and in Connecticut focused on small populations in environments with excellent access to deer. No one had attempted to deal with a population numbering hundreds of deer in an environment ranging from flat, grassy backyards to rugged, wooded ravines
  • Evaluating Immunocontraception for Managing Suburban White-Tailed Deer in Irondequoit, New York, The Journal of Wildlife Management, Apr 2000
  • Deer Population Control (Non-Lethal): An Animal Rights Article from
  • WHITE-TAILED DEER ACTIVITY, CONTRACEPTION, AND ESTROUS CYCLING, SHUMAKE & KILLIAN, Great Plains Wildlife Damage Control Workshop, 1997Although Porcine Zona Pellucida
    (PZP) treatment has been demonstrated to be a highly effective immunocontraceptive for preventing pregnancies in white-tailed deer, treated does also show extended estrous cycling beyond the normal rut season (Turner et al. 1992; Shumake and Wilhelm 1995) and 3 or 4 extra cycles are not uncommon. Bucks are normally attracted to powerful chemosignals generated in does at the time of estrus (Murphy et al. 1994) and their behavior toward individual does can be used to detect receptive animals.

Comments are closed.