Science proves PZP is sterilizing wild horses

The truth

The Effects of Porcine Zona Pellucida Immunocontraception on Health and Behavior of Feral Horses (Equus caballus)

Authors: Knight, Colleen M.
Advisors: Rubenstein, Daniel I.
Department: Ecology and Evolutionary Biology

The horse population on Shackleford Banks, a barrier island off the coast of North Carolina, has been controlled using a program of porcine zona pellucida immunocontraception since 2000. Prior studies found no negative physiological effects of the immunization, but suggested some adverse effects on behavior such as increased harem switching and extended reproductive season. Although no mares were immunized in the year of study (2013), we examined the effects of past contraception and foaling on health and behavior of the mares in an attempt to better understand its impacts on both the individual and the population. Current lactation was found to be the best predictor of health and behavior: lactating mares were in worse physical condition, spent more time grazing, and switched harems fewer times. Mares that had never foaled also were in better physical condition than mares that had foaled in the past, but did not differ in behavioral measures. There were indications that the PZP treatment has had effects other than preventing pregnancy: an increased number of years since immunization was correlated with better body condition and fewer harem switches, independent of lactation. Contraception treatment intensity or timing did not have any significant adverse effects on health and behavior on its own. However, three or more consecutive years of treatment or administration of the first dose before sexual maturity may have triggered infertility in some mares. Inducing sterility, while relieving the mares from the energetic costs of lactation and reducing the stress from harem switching, may have unintended consequences on population dynamics by increasing longevity and eliminating the mares’ ability to contribute genetically.

Read more here:

Sign and share the urgent petition: Grant a 10-year moratorium on wild horse roundups for recovery and studies

PZP is an EPA approved restricted use pesticide and Protect Mustangs is against using it on wild mares especially when there is an underpopulation problem on public land despite government spin. The truth is most wild herds are being threatened with low numbers and a lack of genetic variability.

9 thoughts on “Science proves PZP is sterilizing wild horses

  1. The low viability is a reality in so many herds now. These past 5 years (and before when many herds were zeroed out and could not even be found in holding because there was none then…) we have seen the herds disappear and then others gutted of their old and young. The behavior of our wild horses is in jeopardy. They have yet to have ongoing studies. They need this. BLM wants them gone so fast that doing a census has become paramount. Independent study is sited in the 1971 Act. Why are people wanting to drug wildlife that the nation loves and have shouted out their support for wild horses and wild burros on their lands be saved and protected from BLM attacks, removals and preference to others who are only to be guests on the horses lands?

  2. I had read this awhile back. But here’s the problem — this finding is not the only negative published report, showing sterility of Wild Horse Mares being done — it is one of a few reports. But again, even though EPA approved “Restricted Use” parameters of PZP, it did not cloak or underestimate the facts about horse flesh being poisoned by the PZP — yes, even though the actual product of the PZP chemical itself is essentially out of a horses system, the flesh and meaty tissues, liver, et al. are still polluted with dangerous drug — thereby the warning “Not for Human Consumption” as well as “Harmful to Predators”, as well as “Harmful to Fish and Ecological Systems” and especially around water sources, and especially to general wildlife populations if digested! Consider this, if the idiots and criminals at the BLM say something positive about it, question it immediately, because they have no idea about the managing or taking care of wild horses or Public Lands and the wildlife out there! If you doubt that, drive by a BLM corral, or watch how they do roundups — these are the people some of you think are okay! To that I and many others say — BUNK!

  3. The BLM, government and the cattlemen all have never had the best interest of the horses period! The wild horses are NOT ferrel like they would like you to believe it is about land, money and pay offs. Yes pay offs! When it comes to kill buyers and PZP favors are called in and that is unacceptable! PZP sterilizes horses which leads to zeroing out of the wild horses. 80% of the US love the horses and do not want them harmed. Cattlemen call them cockroaches. The BLM has also used this same description to describe the wild horses. Leave OUR wild horses wild!

  4. We have to get through to the people who are suppose to care for the mustangs. I sure don’t have the answer but if they can’t destroy the herds with roundups they give young mares pzp and sterile them throwing of the whole band process that has worked for wild horses for way longer than any of us have been alive. Studies by the Department of the Interior and specifically the BLM are a waste of time and money. They do not proof anything useful to the horses only what they want to do to them and get rid of them anyway possible. These mustangs are being treated like test animals and I’m very sure that’s not what Mustang Annie had in mind when she fought so hard to pass the 1971 Mustang and Burro Act. Please stop destroying our horses there is absolutely no sense in it and as you reap you will sow.

  5. PZP is another aspect of a foolish government effort to interfere with nature. It would be far better to remove all cattle from the wild horse HMAs and disavow the concept of AMLs. Fiddling around with pesticides in an effort to reduce the wild horse population might temporarily satisfy welfare ranchers and their politicians, but their real goal is the removal of any competition for their grazing “rights”.

  6. Our WH&B’s are a NATIVE SPECIES proven by DNA and FOSSIL PROOF stop poisoning them. These magnificent horses and burros are a national treasure to most Americans we do not want them poisoned and sent to slaughter we want them FREE. BLM and welfare ranchers want them gone why…. MONEY. Our WH&B’S ARE NOT ONLY NATIVE TO OUR NORTH AMERICAN CONTINENT THEY ARE A PIECE OF OUR HISTORY SINCE THE LAST ICE AGE.

  7. Well well, sad state of affairs when birth control becomes an irreversible lack of fertility for a creature we should be revering – they helped us build our countries after all…in the days before machines. These are some of the best horses we have in our herds on Planet Earth – yeah some may disagree, but I know better having had some to compare them to – they have sustained their breed through the means of survival of the fittest, not by forced pedigrees! The human population will regret this medical intervention that has been taken against the wild horses one day, especially if we continue on this path. Hopefully we will realize it before it is too late, unlike other animals that have fallen into extinction.

  8. There is no need for drugging horses, they have maintained themselves for thousands of years and now we have hundreds of people willing to monitor and care for these beautiful beings there are no excuses other than GREED and LAND GRABBING and that is fact. The round ups need to stop its barbaric cruel and disgusting and done with lies to the public for a few extra bucks sad people indeed sad weak cowards that will pay for this in the end. Peace James.

Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.