Search Our Site

Search form


Spring 2006 - Act•ionLine

by Daniel Hammer | Spring 2006

Putting Other Animals on the Pill

Putting Other Animals on the Pill: Should We, or Shouldn’t We?

Friends of Animals has enabled the neutering of over two million cats and dogs — domestic animals that humans brought into society as dependent beings. Does this imply that it’s ethically justifiable to control the births and populations of animals living independently of us?1 Here, Daniel Hammer argues that birth control of naturally existing populations falls short of respecting their basic interests.

Over the last quarter-century, advocates have come to view reproductive control as a practical, non-lethal way to manage free-living animals. It’s not often discussed in action alerts, except when offered as an immediate way to avoid killing. For example, in areas where hunting is debated, or where great numbers of animals are being hit by cars, advocates may propose, or even insist, that officials consider reproductive control as a solution.

If the individuals involved in pilot reproductive control projects were from particular human populations, questions would be asked about the rights of the community being invasively controlled. Regarding nonhuman animals, though, this discussion hasn’t emerged. Reproductive control is, for the most part, considered a benign intervention. Animal experimenters Jay F. Kirkpatrick and Allen T. Rutberg insist: “Not only is this ethically defensible, but (more to the point) it is also widespread, and we do not see this consensus changing in our lifetime.”2

When communities perceive conflicts between the animals around them and their own needs and desires, we, the human beings who make decisions, have a responsibility to ensure that our proposed answers reflect our values.3 Can we claim to value the “intrinsic rights of all wild creatures to live out their lives unmanipulated by humans,” as Kirkpatrick and Rutberg put it, but, “as a practical matter,” give into “public demands that action be taken when public health, safety, or subsistence are threatened by wildlife”?4

If we think other animals have intrinsic rights — interests that are due serious moral consideration — then public demands do not settle the matter. Rights can be inconvenient, yes. But that’s when they count. The point of rights is to protect individuals against intrusions that might be convenient to others. Here, then, is an analysis of this oft-overlooked issue, beginning with a review of its factual background and concluding with some thoughts on the need for a more enlightened advocacy when it comes to respecting the basic rights of free-living individuals.

Reproductive Control: What’s Available

A variety of reproductive controls exist as an alternative to lethal control over free-living animals. They include sterilization, contraception, and contragestation.


Sterilization is usually surgical and permanent. In 1997, the Alaska Board of Game authorized the experimental sterilization of the alpha pairs in 15 wolf groups with territory in the Fortymile region of central Alaska. Scientists cut and plugged the wolves’ reproductive tubes. The other group members were relocated or killed off under the wolf-control scheme in the interest of providing human hunters greater opportunities to kill caribou.5 In 2004, state biologist Jeff Gross touted the scheme as “a real viable management option.” Gross exclaimed, “It’s shown it’s got some longevity. It really is a cost-effective means to reduce the numbers in the long run.”6

The idea wasn’t a new one. It’s based on similar projects in Minnesota and the Yukon. The Yukon, which pioneered it, is now experimenting with immunocontraception. 7


Immunocontraception is one of the newest and most fashionable forms of reproductive control for free-living animals.8

Immunocontraception is now being tested on deer, elephants, bears and birds, and, most of all, on free-living horses. Federal legislation designed to protect the lives of horses on public lands led the Bureau of Land Management be one of the first agencies to back experiments contraception as a way to continue aggressive management practices.

In 1977, the BLM offered $300,000 for experiments, led by Jay Kirkpatrick, to test the effects of large doses of testosterone in stallions. Infertility was established, but the public backlash over the treatment of horses doomed the experiment.

In 1985, the BLM allocated $750,000 for more experiments. Kirkpatrick’s team lost out to an experiment on surgically implanting steroids in mares. So the team applied to the National Park Service for clearance to continue testosterone experiments on the stallions of the Assateague Island National Seashore, off the coast of Maryland. Here again, the experiments showed contraceptive promise, but Kirkpatrick noted that “the stresses for the animals were significant.” There were further questions as well. Kirkpatrick added, “At this point, no one had even considered the passage of the drugs through the food chain… Nor did anyone consider the long-term pathologies associated with these hormones.” 9

Following the testosterone experiments, Kirkpatrick’s research team joined with researchers at the University of California (UC-Davis) to subject the Assateague horses to a study of the immunocontraceptive porcine zona pellucida, or PZP. After the researchers published their findings in 1990, the immunocontraceptive idea found support in several key sectors, from the National Institutes of Health to the American Zoo and Aquarium Association. Starting in 1991, with the support of Senator Harry Reid of Nevada, “a large sum of money — perhaps a million dollars — was appropriated to the BLM over the next ten years for the development if a one-inoculation vaccine that would have contraceptive effects for two to three years.”10

The U.S. Food and Drug Administration hasn’t approved the drug, but it has granted Kirkpatrick an Investigational New Animal Drug exemption to use PZP on deer, free-living horses and zoo animals — a permission which Kirkpatrick turned over to a sponsorship by the Humane Society of the United States.11 In 1992, the Humane Society and the BLM signed a Memorandum of Agreement to cosponsor the first immunocontraception experiments using PZP in the free-living horses of the west. As Jay Kirkpatrick explained it, “The HSUS provided [the BLM] with the political cover needed to pursue contraception after the humane catastrophe of the 1980s steroid studies.”12 In November 2005, HSUS announced a new Memorandum of Understanding to cooperate on “further development and wider use of contraception in wild horse populations.”13


Also in November 2005, the federal Environmental Protection Agency approved registration of the pesticide OvoControl-G14, a nicarbazin-based chemical used on Canada geese. A contragestative, it prevents gestation after conception has already taken place. According to the EPA, the registration of OvoControl-G was strongly supported by the Humane Society of the United States, as well as the U.S. Department of Agriculture’s National Wildlife Research Center, which conducted field experiments with the chemical.

In addition to promoting PZP and nicarbazin, the U.S. Humane Society has been a strong proponent of egg addling as a contragestative method for controlling Canadian geese and other wild birds. The new chemical means, in the Humane Society’s view, “In a sense, the egg is addled inside the goose.”15

For its part, the National Wildlife Research Center experiments extensively on the reproductive control of free-living animals, applying SpaVac and other hormone-based immunocontraceptives primarily on deer, but also developing such drugs for other animals. Then there is DiazaCon, a cholesterol reducer that blocks hormones and is being developed to control small birds and mammals such as monk parakeets and prairie dogs.

Researchers, Control Thyselves

Let’s return to the statement of researchers Kirkpatrick and Rutberg: “The public demands that action be taken when public health, safety, or subsistence are threatened by wildlife. Not only is this ethically defensible, but (more to the point) it is also widespread, and we do not see this consensus changing in our lifetime.”16

While the Humane Society supports the manipulation of horses and geese, these animals pose no serious conflicts. Along with Kirkpatrick and Rutberg, the Humane Society takes for granted the need to control animals, so that it’s ethically defensible to override the interests of nonhuman animals wherever humans perceive a conflict. Thus, horses should be rendered infertile where their presence interferes with cattle ranchers — and what threat exists there, other than the “health” of the ranchers’ profit? The gestation of goose eggs can be hindered when the birds’ presence annoys golfers or the landscapers at business parks. Bears are deemed too numerous for New Jersey residents’ risk-averse views; the Humane Society has, therefore, been conducting contraceptive experiments on bears at a Jackson, NJ amusement park. This discounts the interests of free-living animals to experience life on their own terms. And it's aligned with the prevailing wildlife management view, a view imbedded in the structure of state and federal agencies: that wildlife should be managed for the use, benefit and enjoyment of people. This view is undeniably widespread; however, contrary to what Kirkpatrick and Rutberg state, appealing to the status quo fails to make reproductive control ethically defensible.

Terms like “overabundant” and “overpopulation” are liberally applied wherever free-living animals are deemed inconvenient. The underlying message is that, if not controlled, free-living animals will take over. This both reflects and supports the systematic acceptance of control, and treats all of nature as a zoo. By focusing on questions such as how will we or where will we use reproductive controls, proponents are able to avoid confronting the ethical question: the question of will we or won’t we accept the systematic manipulation of free-living animals.17 This is the precise question that Kirkpatrick’s team ruled out; deciding that public demands automatically answered it. In reality, the public has never seriously thought about the issue, mainly because many of the animals’ advocates have taken control for granted.

The policies of the Humane Society of the United States, like those of the agriculture department’s Wildlife Services and other management agencies, dismiss the intrinsic interests of free-living animals. For the avoidance of death is not the only interest animals have at stake. The quality of life, including the opportunity to enjoy that life on nature’s terms and not our terms, is, from an animal rights perspective, just as significant as the opportunity to experience life itself.

What’s more, reproductive controls and other invasive manipulations disregard free-living animals’ vital interests simply to gratify human profit or convenience. And increasingly they reinforce the idea that nature poses problems, warranting pharmaceutical solutions. An enlightened advocacy will have to start asking basic questions about that idea. Let’s begin at the beginning: Will we or won’t we accept the systematic manipulation of free-living animals?

  • 1. An editor’s note in the Winter 2005-2006 issue of Act•ionLine states: “It’s entirely rational to oppose the sterilization of deer, wolves, bears, and other free-living animals. We respect their interests in living on their own terms. If there is a conflict, it’s due to our own roads, strip malls, and enormous agribusiness sites — combined with cyclical attempts to manage and control other animals. Birth control efforts should focus on domestic animals — and that includes Homo sapiens, too.” (Response to letter Re: “How to Help Your Community Live With Deer.”)
  • 2. Jay F. Kirkpatrick and Allen T. Rutberg, “Fertility Control in Animals,” The State of the Animals 2001 (Humane Society Press, 2001).

    See, e.g., Ingrid J. Porton, “Ethics of Wildlife Contraception,” in Cheryl S. Asa and Ingrid J. Porton, eds., Wildlife Contraception: Issues, Methods, and Applications (Smithsonian Institution, 2004)

  • 3. “Fertility Control in Animals” (note 1 above).
  • 4. Hunting was a major factor in reducing the Fortymile caribou herd from an original 500,000 members to 5,000 members by 1975. “Wolf Sterilization Program Helps Caribou Herd,” Associated Press (9 Nov. 2002).
  • 5. Tim Mowry, “Sterilized Wolves Seem to Live Longer in the Wild,” Associated Press (7 Apr. 2004).
  • 6. “Wolf Sterilization Program Helps Caribou Herd,” Associated Press (9 Nov. 2002)
  • 7. Other experimental contraceptive controls include non-hormonal chemicals, steroid hormones, non-steroidal hormones, and barriers.
  • 8. Jay F. Kirkpatrick, “The Elusive Promise of Wildlife Contraception: A Personal Perspective,” in Allen T. Rutberg, ed., Humane Wildlife Solutions: The Role of Immunocontraception (2005).
  • 9. Ibid.
  • 10. Ibid.
  • 11. Ibid.
  • 12. Humane Society of the United States press release, “Plan to Increase Wild Horse Contraception Announced” (30 Nov. 2005).
  • 13. U.S. Environmental Protection Agency Office of Prevention, Pesticides and Toxic Substances Pesticide Fact Sheet (Nov. 2005). OvoControl is a trademarked product of Innolytics, LLC.
  • 14. Humane Society of the United States, “Controlling the Hatch May Open New Doors,” Goose Tracks (Winter 2004).
  • 15. “Fertility Control in Animals” (note 1 above).
  • 16. See R. Bruce Gill and Michael W. Miller, “Thunder in the Distance: The Emerging Policy Debate Over Wildlife Contraception,” Symposium: Contraception in Wildlife Management (26-28 Oct. 1993, Denver, Colorado), stating: “Left unmanaged, the wildlife contraception controversy will devolve into confrontational question of will we or won’t we. The challenge of the wildlife policy decision process will be to focus the debate on circumstantial questions such as how will we or where will we.” (Emphasis in original.) On the issue of pet cloning, Lee Hall has written: “The issue deserves much more morally serious consideration. The public needs to think hard about the boundaries being crossed in this peculiar legal sphere where property meets personality. It’s time to ask not just whether we can clone pets but whether we should.” Lee Hall, “Carbon Copies,” Legal Times (5 Dec. 2005; emphasis in original). The same ethical question must be posed with regard to the deliberate manipulation of free-living animals.
  • 17.
Daniel Hammer

Act•ionLine Spring 2006

lineBack to Top
line line Page 7 of 9 line line