update on "super birth control pill"
-Senestech severs ties with 600 million stray dogs need you

April 8, 2011
(Click here to view as a PDF)

On April 4, 2011, SenesTech notified ACC&D that they have severed ties with the organization 600 Million Stray Dogs Need You (“600 Million”) and its founder, Alex Pacheco, and that “neither 600 Million nor Mr. Pacheco have any claim, right, title, license or interest in our ChemSpay™ product or any other [SenesTech] product.” (Although the separation is official, content on the 600 Million website still seems to refer to this technology in fundraising appeals.)

On December 22, 2010, ACC&D responded to claims being made by 600 Million and its then partner, SenesTech, about their non-surgical sterilant technology, ChemSpay. At that time, we expressed our concerns about the unfounded statements being made – especially by 600 Million – about the effectiveness and safety of ChemSpay. The treatment was being presented as proven and ready to be submitted for regulatory approval, but no data was presented to support those claims. Even lead SenesTech researcher Dr. Loretta Mayer conceded that the technology is still at an early stage for use in dogs.

Today, Dr. Mayer remains hopeful about ChemSpay and plans to continue work to advance this technology for dogs. In a recent interview for The Bark magazine, Dr. Mayer stated: “This isn’t a pill sitting on my desk: this is a technology based on scientific fact that we believe can be developed….We believe that anything that decreases eggs in the ovary of one mammal can also deplete them in another mammal, but that is an academic argument that hasn’t been tested yet.”

In communication with ACC&D, Dr. Mayer says she hopes to share new data from SenesTech with ACC&D.  ACC&D will continue to track progress with ChemSpay and will share updates as they become available.

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ACC&D’s December 22, 2010 release can be viewed below. The article in The Bark magazine can be accessed through this link.


The Science (lags) Behind the Story

-Data supporting claims of a “Super Birth Control Pill” leaves much to be desired

December 22, 2010
(Click here to view as PDF)

Animal advocates around the world are eager for safe, effective, affordable, non-surgical methods to prevent the births of unwanted puppies. And when 600 Million Stray Dogs Need You (founded by Alex Pacheco, co-founder of PETA) announced early this year that they had found a birth control pill that causes sterility and is completely safe and effective, it sounded like a dream come true. So is it a dream, or is it true? The president of the Alliance for Contraception of Cats and Dogs (ACC&D), Joyce Briggs, attended a briefing held by 600 Million Stray Dogs in Los Angeles on December 2, 2010, eager to find that this dog sterilization pill was indeed a reality. Unfortunately, it appears that the scientific data lags far behind the story being told by 600 Million Stray Dogs Need You.

The Alliance for Contraception in Cats & Dogs (ACC&D) first learned of this approach—called ChemSpay and developed by a company called Senestech—in 2004. We were intrigued by published data from studies in mice which showed that several weeks or more of daily treatments caused sterility, and by the company’s suggestion that this technology might also work in dogs and cats. Results that Senestech shared in 2007 from studies in a small number of dogs (supported in part by funding from ACC&D), were less promising, bringing to light some significant hurdles to demonstrating safety and efficacy. In 2008, Senestech’s research turned back to birth control for mice and rats (which are responsible for the devastation of rice crops around the world), though the researchers planned to return to work in dogs in the future. ACC&D remained interested in this technology, while recognizing that it was still in the very early stages of development and that success in rodents would not necessarily translate to dogs and cats.

Now ChemSpay for dogs is back in the limelight, thanks to a partnership between the nonprofit organization 600 Million Stray Dogs Need You and Senestech. (The fact that Senestech is the technology partner for this new non-profit was just revealed in late November in invitations to the December 2nd briefing.) But while 600 Million Stray Dogs Need You is quick to make specific promises that this technology works in dogs (and that, when work is completed, a single treatment will be effective), the scientific data shared to date do not support these statements. At the briefing, previously published results from studies in mice were described, but although over 270 dogs are said to have been included in studies, only a few examples were given of effects on dog ovaries, with little detail about dose, route of administration, number of doses used, or even number of dogs tested. ABC Los Angeles, which attended the December 2nd briefing and interviewed the researchers, reported that three or four oral doses sterilized just 20% of the dogs in one study. “Although we were hopeful that new data would be introduced at the briefing showing that Chemspay, given either as an injection or a pill, sterilized dogs, we were disappointed that there was no documentation of any significant achievements beyond what was shared with us in 2007,” commented ACC&D president Joyce Briggs. Even Dr. Loretta Mayer, lead researcher working on the ChemSpay project conceded that the technology is still at an early stage for use in dogs. But communications from 600 Million Stray Dogs Need You suggest that the technology is ready to be submitted for regulatory approval.

In addition to a shortage of data showing the technology works, there are also some key questions about safety that remain unanswered. Senestech asserted at the briefing that since the targeted reproductive pathways are conserved across all mammalian species, this chemical will certainly sterilize female dogs as it does mice. However, oddly, they also stated that the chemical does not have any effects in primates and is completely safe for humans (also mammals). The chemical in Chemspay is 4-vinylcyclohexene diepoxide (VCD), used widely in manufacturing products such as tires, polyesters, and epoxy resins. Other work with VCD showed that it does in fact impact fertility in monkeys(1) although subsequent work was not been able to replicate this result(2). VCD has also been shown to be a dermal carcinogen in mice and rats after multiple applications to the skin(3), which raises questions about safety in other species. Given such findings, much work will be needed to substantiate the claims being made that this compound is safe and effective for use in dogs and that it will have no impact on women handling it.

The invitation to the briefing noted that that “Cheetah, one of the first dogs in the world to be sterilized without surgery, [would] be available for visits.” Dr. Mayer shared that Cheetah was treated nearly six years ago with multiple injection treatments of ChemSpay and then surgically had her ovaries removed to examine the effects of the treatment. Yet, those results showed 67% depletion of primordial follicles, with no data to show sterility. Cheetah is sterile now, since her ovaries were removed after treatment.

ACC&D is committed to basing our communications and actions on sound science. Our Board of Directors and Scientific Advisory Board include experts in animal welfare, animal health, veterinary medicine (including dog and cat reproduction), international dog and cat population control, regulatory requirements for animal health products, and public health. “We believe it's critical that stakeholders in this work are provided with accurate information and a realistic picture of the most promising paths toward more humane and effective methods of controlling unwanted cat and dog populations,” writes ACC&D board chair Linda Rhodes, a veterinarian and PhD specializing in the regulatory submission and review process for animal health products. “We’re concerned to see these statements being made about this technology unsupported by facts and data. Based on what has been shared publically, there is still a long way to go to prove that this approach is as safe and effective as claimed by 600 Million Stray Dogs and Senestech. ACC&D will seek clarification and new information about this technology, and will share important updates.”

ACC&D hopes to see technologies advance that can provide safe and effective sterilization for dogs as well as cats. We look forward to seeing more data to demonstrate that this chemical may become a new tool for those working to humanely control pet populations everywhere, and we encourage 600 Million Stray Dogs Need You and Senestech to share that data with the public as they ask for donations. While there are many unanswered questions here, what is not in doubt is the critical need for faster, easier, less expensive and less invasive methods for sterilizing cats and dogs and preventing unwanted litters.

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The Alliance for Contraception in Cats & Dogs (ACC&D) is a nonprofit animal welfare organization based in the U.S. but with global scope. Our mission, pursued over the last 10 years, is to expedite the successful introduction of methods to non-surgically sterilize dogs and cats and to support the distribution and promotion of these products to humanely control cat and dog populations worldwide. ACC&D’s efforts are supported by over 120 Organizational Partners: animal welfare, animal health, and public health organizations from around the world. Please see www.acc-d.org for a list of our Board of Directors and Scientific Advisory Board and to learn more about our work.


1.Amppt SE, Kaplan JR, Clarkson TB, Cline JM, Christian PJ, Hoyer PB, Destruction of primordidal ovarian follicles in adult cynomolgus macaques after exposure to 4-vinyl cyclohexene diepoxide: a nonhuman primate model of the menopausal transition. Fertility and Sterility, v. 86, issue 4, supplement, pgs 1210-1216, 2006. (Full article available at http://www.fertstert.org/article/S0015-0282(06)01185-X/abstract)

 2. http://www.flinn.org/news/756

 3. Maronpot RR, Ovarian toxicity and carcinogenicity in eight recent National Toxicology Program studies, Envirn Heatlh Perspect v. 73, pgs 125-130, 1987. (Full article at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1474570/)