Wild Horses: Randy Harris Photo

EPA classifies wild horse birth control drug PZP as a pesticide

WILD HORSES (US) — This is not news; simply a clarification. Certain readers have questioned our reference to PZP (Porcine Zona Pellucida) as a pesticide which is used as a type of birth control on wild mares living on federal lands.

EPA Pesticide Fact Sheet p. 1.
Click image to view the EPA’s full Pesticide Fact Sheet on PZP (pdf, 9 pp).

As Protect Mustangs state:

Pests are invasive species. Wild horses are native.

Drugging up wild horses with a dangerous pesticide sterilizes after multiple uses. The pesticide also ruins natural selection and wrecks havoc with native wild horses’ immune systems putting them at risk of massive die-offs.

Protect the Harvest writes:

When it comes to the feral horse issue in the American West, the only thing that needs to be sterilized are the bad ideas coming from animal rights activists.

That hasn’t stopped groups such as Wild Horse Education from muddying the debate over how to handle feral horse overpopulation. A group that is assisting WHE in its foolishness and has only served to make things more difficult for these horses and the people who are trying to help them is the Humane Society of the United States (HSUS).

The Horse Fund are against the use of PZP on wild horses not only because it is a dangerous pesticide but also because of the federal government’s continuous interference and mismanagement has them on the verge of extinction.

The Department of Interior’s Bureau of Land Managment’s Wild Horse & Burros Management Program has decimated entire herd management areas leaving the few existing herds in danger of being wiped out.

Food for thought.

We also notice that it states “nonfood use” twice on the EPA’s PZP cover page (above). Since wild horses are sent to slaughter from time to time for for human consumption, wild mares treated with PZP are barred from entering the human chain.

Wild Horses: Randy Harris Photo.

25 thoughts on “EPA classifies wild horse birth control drug PZP as a pesticide”

    1. We appreciate your comment but facts are facts. There are no alternative facts or differing facts – a popular notion at the moment. There are however differing views whether or not to use them and we say absolutely not. We will continue to cover this issue.


  1. Protect the Harvest and Dave Duquette are laughing at you for writing this article. In fact, they’re likely cheering!! Allow me to state this: pzp is NOT a pesticide. It was labeled as such by the EPA where the deer population was rampant. Get your facts straight. Herds are not purposively inoculated to sterilize them, that’s the kind of bs frank Lucas, Dave Duquette, and Anne Novak love. I’m disappointed your publication has stooped so low, so long! Won’t be reading your publication any longer and discouraging others as well to avoid

    Liked by 1 person

      1. from reading the comments, the pattern of response is clear; horse lovers who have no scientific background cheer the prospect of herd control and thus keeping the BLM away. Those with a background in Biology or Medicine have detected a large potential problem with PZP, it works by causing inflammation and thus can sterilize the mare especially if used multiple times. The chemical also causes some behavioral problems and should never be given to a mare who has recently foaled! She may literally walk away from her foal. There is no question that we need a compound that is contraceptive in nature, but safe. As a Doctor, I compare the road that we are now traveling with horses to be not unlike the early contraceptive approaches in humans not that many years ago. There may be better products and we must stay objective and keep looking.

        Liked by 2 people

  2. This entire becomes null and void as soon as you make the statement that PZP is a pesticide, without the qualification that it is only a pesticide by category and not by content. You also post a fact sheet, where the red lettering saying sterilizes after multiple use had been ADDED to it.

    I have always admired your articles, but see that I will have to unsubscribe and tell our readers from Citizens Against Equine Slaughter, Oregon Wild Horse & Burro Association, Wild Gorse Action Group, Public Lands Truth Campaign, and our partners that this publication now spouts alternative facts.

    Yes you are stating your opinion, but you have not stated it and presented all the facts have you?

    To the person with the comments about Assateague having mare inflammation and foals born with abnormalities, will you please provide proof of where you found this information because I am not able to verify it, and I work closely with those who oversee the PZP program there. I also have worked extensively with Cornell U and will be calling them in the morning to discuss your claim about deer because I cannot find those results listed anywhere either.

    We all know wild horses are not overpopulated when you add the total on the range. But there are some herds that are too large for the area they are in. And the very plain, simple fact is that an herd that is over AML is subject to roundups for removals. So, the fight is better spent increasing AML’s and using PZP native (which fyi is NOT in the experimental stage any more), while we fight to increase those AML’s. Fighting PZP applications is only going to do one thing…send them to slaughter.

    With this administration in power if you fight the absolute ONLY tool we have to preserve genetics on the range while we fight to increase their land, remove livestock and increase those AML’s, then you have given our wild horses a death sentence.

    And citing Protect the Harvest….any real advocate knows they do not want PZP used because IT WORKS! They want the horses gone, not managed.

    Liked by 2 people

  3. It is amazing how so many people identifying themselves as wild horse lovers and advocates spend so much time defending PZP. Can you not see that it is being used as a propaganda tool?

    Even a group like Protect the Harvest can see what’s going on and they aren’t even on the side of the horses. That’s why we included them in our post.

    In the past the big selling point trotted out by the big groups for the use of PZP is it would mean fewer helicopter roundups; maybe eventually no helicopter roundups.

    BOTTOM LINE: If it is not (and not not been) necessary for wild horses to be removed from federal lands, why would it be necessary to give mares a pesticide/drug/vaccine to keep them from reproducing which if used incorrectly my make them sterile.

    See what Craig Downer says about it here http://protectmustangs.org/?tag=craig-downer . Downer is a celebrated scientist and an expert on this issue who is on the side of the horses and not a puppet of the big name groups.

    Liked by 4 people

  4. Just so people know, Protect the Harvest (PtH) is against PZP NOT because they’re the good guys. If anything, they are one of, if not, the most extreme anti-animal welfare group in the country. They oppose PZP because A: HSUS supports its usage and because hating on them is a cornerstone on PtH’s philosophy, they will attack them on anything regardless if they’re in the right and B: PtH doesn’t want wild horses and burros to be managed. They don’t even want low herd numbers. To them, so much as one wild Mustang is a threat to their so-called “way of life” (AKA: grazing their livestock on public lands at the expense of the American taxpayer) and as a result want them completely gone. The “people who are trying to help them” line really translates to the people who support slaughtering and euthanizing them. Just look up Protect the Harvest and horse slaughter. A little digging quickly reveals that their intentions are actually insidious. They are the very group lobbying to return horse slaughter back to American soil and our remaining free-roaming horses and burros are their main target.

    Liked by 2 people

    1. You are right on. Protect the Harvest is not who they really are. Big lie and deception! It is all about cattle money for them. And whose pockets are the big cattle companies. I get so sick of hearing the wild horses are at fault….they they pull out the grass by the roots! Not True! It is the other way around. Equines are on the move continuously; cattle stay in one place and don’t leave until it is bare and pulled out of the ground. Someone needs to get this out in the media!

      Liked by 3 people

      1. So true. And I can personally testify to the fact that wild horses are nomadic. When I saw the Salt River wild horses back in November, they typically didn’t spend more than about five minutes in one spot and then they were on the move again. They grazed along and didn’t leave any of the trees barren. It’s almost as if big-ag proponents believe that wild horses are as sedentary as domestic horses who, unlike their free-roaming counterparts, don’t constantly have to be on their move for their survival. I wonder how many of these folks have seen wild horses or burros in their natural habitat. Not from afar as their cattle graze, but up close and personal. And I’m right with you on the media being educated on this, but unfortunately many anti-Mustang groups are powerful lobbying organizations that have a stronger influence over the media.

        Liked by 4 people

      2. The cattle, originally imported from Europe, enjoy standing in cool riparian areas leaving hoof prints and breaking down the slopes and vegetation. Of course, horse haters blame wild horses for these footprints which are nothing like the single hoof prints horses leave.

        Liked by 2 people

  5. Protect the Harvest…..interesting! That would be oil mongrel from southern Indiana with all the big bucks! Seems like those with the big bucks like to throw their weight around! And stop sterilizing our wild horses! And how about getting some actual TRUE numbers out there instead of all the lies they seem to like putting out there. This is all about money; always has been; and always will be as long as corruption, deception, deceit, lying, is allowed to take root. They have absolutely no interesting in the welfare of these wild horses. And if we as Americans remain silent and do nothing, then the wild horses’ blood is on our hands as well. God help us for this travesty. If only we could get someone to tell the truth. Again…..all about the money/greed. Please share these posts with your friends/family. The only way they will know what exactly happened to our national treasure…..the Mustangs! My rant for the day…..

    Liked by 2 people

  6. They’ve been using PZP since the early 1990’s for the Assateague wild horses and it does control the popualtion. https://www.fort.usgs.gov/wildhorsepopulations/contraception

    What is PZP and How Does It Work? http://www.pzpinfo.org/pzp.html

    PZP is not DDT. PZP is a protein that breaks down. That is one of the reasons it is only effective for one year (one reproductive cycle for wild horses, they do not breed like rabbits). The classification is because of the purpose of use and was “put on the books” first in the US for dealing with deer populations for “pest control.” We might not like the term, but the classification is not because this is like DDT or RAID.

    Liked by 1 person

    1. Sorry. No sale. But for argument sake say you are right.

      The BLM have zeroed out entire HMA’s. We have other HMA’s which are close to being zeroed out. Herd numbers are at the lowest they have ever been. There is no reason to use PZP. Absolutely none. It is still in the experimental stage. And the same problems with the deer has happened with horses.

      There is absolutely no reason to treat these horses with PZP. Or spay them in the field. Or any other ideas cruel and dangerous treatments to be carried out on these horses.

      We say it is wrong. Period. We are only presenting our view here because not to would imply we agree with you. And we do not. Nothing personal.

      Liked by 2 people

    2. What we need is a true wild horse population count instead of extrapolation based on 10 year old data. Where is there evidence that wild horses “breed like rabbits”? Assateague Island is being over populated by humans and their structures, therefore any horse that gets fed by humans is removed. Foals are born with abnormalities that should be acknowledged; mares have inflamation. Wild mares are still captured for Pzp injections and some are released back with skewed male/female ratios.
      Regarding the deer population, Pzp caused females to travel much farther to attract bucks than without the pesticide. Normal breeding days for white-tailed deer is 45 days which extends to over 150 days. Cornell U and USDA captured 21 white-tailed deer and discovered after “euthanizing” them that “most of the vaccinated group had lived with pelvic inflammatory disease, and abscesses the researchers called “remarkable”—tubercular in appearance even two years after the injections. The body of Deer Number 188 showed bone marrow fat depletion with “classic signs of malnutrition normally seen in deer struggling through an extremely harsh winter.” http://www.counterpunch.org/2014/01/03/free-living-animals-on-birth-control/

      Liked by 3 people

  7. Every big wild horse organization acknowledges the use of PZP being a safe alternative than roundups of wild horses and burros… The Cloud Foundation, Return To Freedom Wild Horse Sanctuary & Preservation, Wild Horse Freedom Federation and American Wild Horse Campaign… they can’t all be wrong…


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