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And now a word from the wild horse scientist!


Dr. Jay Kirkpatrick, the scientist responsible for the success of PZP, is still very much at the center of contraceptive science for wild horses and other animals. His Science and Conservation Center, in Billings, Montana, not far from the famous Pryor Mountain wild horse herd, is a sort of ground zero for PZP, both its production and ongoing research. And because wild horses in America are at the heart of a complicated, hotly-debated controversy, he has written eloquently of that dilemma. He could write a book on this subject, and I think he should! Actually, he did write one, back in 1994, called Into the Wind, which I highly recommend if you can find it. It’s lovely and informative. But here is a brief update from Jay, director of the Science and Conservation Center in Billings, Montana, developer of the PZP vaccine, and one of the stars of Wild Horse Scientists. Thanks so much, Jay!

The work of the Science and Conservation Center (SCC) is focused on the non-lethal control of wildlife populations, through fertility control, with particular emphasis on horses. To that end the SCC produces the vaccine and trains people to use it properly. Certain wild horse populations are being managed through fertility control for the National Park Service, the Bureau of Land Management, the U.S. Forest Service, wild horse sanctuaries, preserves, and various Native American tribes.

Use of the fertility control vaccine PZP for wild horses has increased slowly over the past 25 years, but not as fast as it might have, largely because of the social, cultural, economic and political forces that oppose this approach. Often who uses the vaccine and who doesn’t depends on the progressiveness of thinking among local wild horse managers, and less on policies. This places much of the work for moving this form of management outside the purview of science.

The SCC also manages some urban deer populations, many zoo animals, free-roaming African elephants and bison with the contraceptive vaccine and it is interesting that this world-wide effort had its birth on the marshes of Assateague Island National Seashore so many years ago.

The SCC also engages in some research activities. One project is the testing of a recombinant form of the vaccine (rZP) as an effective booster inoculation. If rZP works, it will expand the ability to treat many more animals. Production of the native PZP at the SCC is a time consuming, labor-intensive endeavor and if the rZP works, the SCC would only have to produce primer doses (the initial dose) and that would increase dramatically the number of animals that could be treated. Other research includes species’ differences in the response of the PZP vaccine. For example, some recent research shows that it is much more effective in species of the goat and sheep families than in other mammals.

But, wild horses will remain the primary focus of work at the SCC.

For more, here’s a video interview with Jay.

by Kay Frydenborg

About Kay Frydenborg

Kay Frydenborg

Kay Frydenborg fell in love with horses at an early age, and now she often writes about them. She lives in Pennsylvania with her husband and three dogs, and rides her beloved horse, Remy, almost every day. The Wild Horse Scientists is her first book for Houghton Mifflin. Visit her website at

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