PZP is dangerous for the last American herds of wild horses and burros
The old hypothesis — that PZP merely blocks sperm attachment — has been disproved.
Kaur & Prabha (2014) found that the infertility brought on by PZP is ” … a consequence of ovarian dystrophy rather than inhibition of sperm-oocyte interaction.” They reported thatPZP’s antibodies induce ovarian dystrophy, oophoritis (inflammation of the ovaries), destruction of oocytes in all growing follicles, and depletion of resting follicles.
Despite all the hype about PZP being non-hormonal, the manufacturer himself knew that it had an adverse hormonal effect — significantly-lowered estrogen. In 1992, he reported that ” … three consecutive years of PZP treatment may interfere with normal ovarian function as shown by markedly depressed oestrogen secretion.” Thus, PZP is an endocrine disruptor.
Worse yet, Sacco et al. (1981) found that PZP antibodies are transferred from mother to young via the placenta and milk. The transferred antibodies cross-react with and bind to the zonae pellucidae of female offspring. This is bad news because BLM regularly administers PZP to pregnant and lactating mares, who transfer the destructive antibodies to their filly-foals. Thus, the fillies get their first treatment with PZP in utero, while nursing, or both.
Nettles (1997) found an association between PZP and stillbirths. In 2015, the International Society for the Protection of Mustangs and Burros reported that 7 mares previously treated with PZP, when taken off it, were able to get pregnant. However, 6 of those 7 mares — that is, 86 percent — produced foals that were stillborn. All other ISPMB mares that had not been previously injected with PZP successfully birthed healthy foals. Environmental and other conditions were identical. The only variable was PZP. Meanwhile, over on the East Coast, the Corolla herd, long-managed with PZP, has recently experienced birth defects among its newborns.
Gray & Cameron (2010) questioned the supposed benefit of PZP-sterilized mares living much longer than their normal life expectancy, and and Knight & Rubenstein (2014) warned of unintended consequences of PZP’s ironic effect of extended longevity. Ultra-elderly mares take up scarce slots within AML-restricted herds. They consume resources but no longer contribute to the gene-pool. It is detrimental to a population’s genetic viability to carry significant numbers of sterile herd-members way-beyond their normal life-span. Meanwhile, those few foals that are born have to be removed to achieve AML because they’re more adoptable.
Ransom et al. (2013) conducted a longitudinal study of three herds currently being managed by PZP — Little Book Cliffs, McCullough Peaks, and Pryor Mountain. They found that the the birthing season lasted 341 days — nearly year-round — which puts the life of mares and foals in jeopardy. Nature designed the equine birthing-season to occur in Spring, not year-round, and certainly not in the dead of Winter.
Ransom et al. also found that, after suspension of PZP, there was a delay lasting 411.3 days (1.13 years) per each year-of-treatment before mares recovered their fertility. They warned: “Humans are increasingly attempting to manage the planet’s wildlife and habitats with new tools that are often not fully understood. The transient nature of the immunocontraceptive PZP can manifest into extraordinary persistence of infertility with repeated vaccinations, and ultimately can alter birth phenology in horses. This persistence may be of benefit for managing overabundant wildlife, but also suggests caution for use in small refugia or breeding facilities maintained for repatriation of rare species.”
PZP’s manufacturer conceded that it could take up to eight years to recover fertility after just three consecutive PZP treatments.
The study on PZP by Knight & Rubenstein (2014) found that ” … three or more consecutive years of treatment or administration of the first dose before sexual maturity may have triggered infertility in some mares.” These findings are particularly troubling. They suggest that, actually, only two consecutive PZP-treatments may be reversible. Except, that is, in the case of fillies who have not yet reached puberty — they could be sterilized by just one injection.
PZP’s manufacturer was quoted describing PZP as “so safe it is boring.” Independent research shows otherwise — that PZP is a powerful hormone disruptor that could sterilize a female with just one injection. If staff and volunteers believe that PZP is boringly safe, they will be less likely to protect themselves adequately from this dangerous pesticide. Indeed, many of the volunteers are women and, therefore, at risk. Accidental self-injection with PZP could cause them to suffer diseased ovaries and depressed estrogen-levels — in addition to infertility and, potentially, sterility.Consider the magnitude of the risk — the PZP-in-question is a horse-size dose.
~ Marybeth Devlin, Wild Horse Advocate
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Unions, wild equine advocates, scientists and Native Americans take a stand against experiments on wild horses and burros, PZP and sterilization
Redmond, OR (April 13, 2016)—Americans are outraged. A government agency is experimenting and exploiting federally protected wild horses and burros. Advocates, unions and Native Americans are boycotting the Bureau of Land Management’s (BLM) Wild Horse and Burro Advisory Board meeting in Redmond, Oregon today and Thursday. The primary stakeholder—the American public—is being ignored.
“Members of the livestock industry as well as members of the Wild Horse and Burro Advisory Board have suggested slaughter as a management tool for wild horses. Americans won’t stand for it. There would be an outbreak of protests nationwide. We will fight that abuse in the courts if the advisory board dare threaten the welfare of America’s wild horses.” —Stephanie Elias, community outreach organizer for Stop American Wild Horse Slaughter
“The Bureau of Land Management is usurping the caretaking role they have been mandated to uphold and are subjecting the mares in our nation’s wild horse and burro herds to pernicious and needless reproduction experimentation. The universities they are funding to do this research must acknowledge that this would never be of use or value in the domestic horse industry. I believe their agenda needs to be investigated before they are paid to do irrevocable harm to these horses. They have already changed the genetics and natural herd behavior. Ahimsa, do no harm, applies to animals as well as people. This is an abomination and must be stopped.” —Christine DeCarlo, Ph.D. in Zoology from Cornell, Advisory Board member for Protect Mustangs.
“The Wild Horse and Burro Advisory Board is useless, yet quite costly to the taxpayers. Circumventing the laws to protect America’s wild horses on public lands, this board represents ranchers who hold grazing permits on public lands only. The intent purpose of the WH&B Board was to protect and make sure wild horses remain safe and wild, and to regulate those ranchers who threaten, abuse, and even kill America’s wild horses. Not only does this board not protect the wild horses, their actual mission, but continues experimentation and using pesticides like PZP and GonaCon™ as birth control—darting the chemicals into wild horse mares. I speak for many Americans, in that humane principle’s and an ethic balance to manage our wild horses has been lost some time back. It’s time to restore them.” —John Cox, Oregonian and Vietnam Veteran
“The truth is, America’s wild horses are underpopulated on public land today. Even the National Academy of Sciences states there is ‘no evidence’ of overpopulation. The BLM’s arbitrary management levels (AML) are way too low for genetic diversity and survival. Fertility control and sterilization at this point endangers the survival of this cherished native species. Wild horses are indigenous to North America yet now the feds and special interest groups want to sterilize them and push them off public land. We offered to help adopt out all the pregnant mares from the last big Oregon roundup (http://protectmustangs.org/?p=8739) but our offer was ignored. The BLM doesn’t want to adopt out these wild horses they want to exploit them as lab animals. The advisory board is a joke. It’s biased towards slaughter, sterilization, pesticides for birth control and cattle as well as experiments.” —Anne Novak executive director of Protect Mustangs
“We want the burros to have the space they require under the law protecting them. In over a decade visiting the burro herds in the West, I don’t see any evidence of BLM’s claims of overpopulation. Everywhere I go it’s getting harder and harder to see burros and many have vanished all together. Why would people want to sterilize or inject the last surviving wild burro herds with pesticides like PZP for birth control? PZP is a slow road to extinction. What we need is creditable population counts for all the remaining burro herds. Advocates and BLM should work jointly for the census. Then we can find out what the real situation is.” —Carl Mrozek, filmmaker and contributor to CBS Sunday Morning
“The wild horse and burro program states that the number of adoptions have significantly gone downhill over a number of years because the market for them has decreased. But the truth is the BLM staff in charge of the BLM Internet adoption auctions do not make themselves available during the internet auction to process the applications required to bid. Since the BLM isn’t allowing employees to adopt loads of wild horses to sell them quickly for slaughter like they used to—adoptions have dropped. BLM’s forte is mismanagement whether it’s the horses and burros or their own staff.” —Afroditi Katsikis, founder of Tweet Equine
“We need to restore wild horse and burro areas as well as protections promised in the 1971 Wild Horse and Burro Protection Bill. I would like to see Craig Downer’s Reserve Design succeed. Let’s keep in mind that wild horses are a ‘climax’ species and predators must be allowed as nature intended. Given a balanced ecology, which can be restored, wild horse population will self-regulate.” —Susan Leffingwell, director of Wind Dancer Wild Horse and Burro Preserve
“We the people of the Alaskan Tlingit Nation stand against the use of PZP and the sterilization of wild mustangs. Like the buffalo, the wolf, the bear and other animals the horse is just as sacred to our people as the bible is to Christians, the Koran to Muslims, Buddha to Buddhists. The use of PZP, ovarian ligation, or any form of sterilization would be considered sacrilege and an insult to our people and the majority of native people everywhere.” —Rudy Al James, federal tribal judge (Tlingkit Nation)
“PZP sterilizes our wild horses and destroys the wild mares’ reproductive organs. The pesticide disrupts the stability of the herds, causes fighting, still borns, birth defects, etc. and therefore we are against it.” —Tina Wooten, Salt River Wild Horse photographer and artist
“We have a lot to study and learn about America’s wild horses. If they are used as lab animals for experiments and sterilized then we can’t study their natural behaviors in the wild. —Anne Novak, founder of the American Wild Horse Institute
“Public land belongs to all of the American people not the livestock industry. There are 5 million cattle and very few Wild Horses. More than 80% of the American public wants our iconic wild horses to be wild and free—unencumbered by any government experimental birth control like the pesticides PZP, GpnaCon™, ovarian ligation or other heinous sterilizations. The livestock industry is the number one cause of global warming and is destroying America’s ecosystems and wildlife. Wild horses manage their own numbers and we want them left alone!” —Peter Souza, founder of the Wolf, Wildlife, Wild Horse Action Group (WWWHAG)
“As a person of Yaqui ancestry I am angered and saddened by the outrageous actions of our Government in their callous disregard and lack of respect for the wild mustangs in the western United States. These beautiful creatures need to exist unmolested and unfettered so they may live in harmony with nature, as it was meant to be. I implore you to cease your heinous acts of sterilization and blatant slaughter of these beautiful creatures in your grossly misguided efforts to control their population at the behest of disgruntled farmers or corporate interests.” —Debra Pavone (Yaqui Nation)
“As a collective of concerned union representatives, Native Americans and citizens, we strongly urge that the board and universities refrain from taking part in any practice of experimentation, sterilization or the use of PZP on any and all wild horses and burros.
We ask that you don’t play God, judge, jury and executioner.
Must we remind you that crimes against humanity also includes animals. It is not only wrong ethically and morally but once again it is wasteful spending of our tax dollars. The legal implications this can lead to will only cause millions of tax dollars to be wasted in the courts. PZP. sterilization and experimentation is bad for the economy, bad for the wild horses, bad for America and a bad idea!” —Randall Massaro, President of Unions for the Preservation of Wildlife
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FACT SHEET: The Truth about PZP
EXPANDED SUMMARY OF PZP’S ADVERSE EFFECTS, INCLUDING REFERENCES
PZP — The Pesticide
Porcine zona pellucida (PZP aka ZonaStat-H or Native PZP) is an EPA-registered pesticide derived from the ovaries of slaughtered pigs. PZP is approved for use on wild horses “in areas where they have become a nuisance ….” 
Some persons argue that, because PZP does not kill the mare, it is not really a “pesticide.” Actually, PZP does kill. As will be documented in this report, its use is associated with stillborn foals. In the long term, PZP will weaken a herd immunologically, which could swiftly lead to its extinction. So, yes, PZP is a real pesticide.
PZP — an Anti-Vaccine
While touted as a “vaccine,” PZP is actually a perversion of what a true vaccine is supposed to be. Instead of preventing disease, PZP causes disease — auto-immune disease. Thus, PZP is an anti-vaccine.
PZP’s Mode of Action as Stated in the Pesticide Registration Is a Disproved Hypothesis
The registrant of PZP advised the Environmental Protection Agency (EPA) that, based on information from the pesticide’s researcher-manufacturer, PZP works by generating antibodies that “block sperm attachment.” This representation of PZP as a sort of chemical condom was not fact but merely an untested hypothesis, postulated three decades ago. The old hypothesis was disproved by subsequent research. PZP’s manufacturer knew, or should have known, this. The manufacturer should also have been informed and up-to-date regarding the side effects and unintended consequences of PZP. Yet, the manufacturer continued to cite the disproved hypothesis and to deny that PZP has any adverse effects. [7 and 13]
PZP’s True Mode-of-Action
So how does PZP really work? PZP tricks the immune system into waging war on the ovaries. In a meta-analysis of ZP-type contraceptives, Kaur & Prabha (2014) reported that the infertility brought on by such products is ” … a consequence of ovarian dystrophy rather than inhibition of sperm-oocyte interaction.” Thus, PZP’s antibodies “work” not by blocking sperm attachment but by destroying the ovaries. Kaur & Prabha further disclosed that ” … histological examination of ovaries of immunized animals revealed the presence of atretic follicles with degenerating oocytes.”  [Atretic follicles are ovarian follicles in an undeveloped state due to immaturity, poor nutrition or systemic disease; manifested by prolonged anestrus.]
Kaur & Prabha’s review concluded that PZP’s antibodies induce ovarian dystrophy, oophoritis (inflammation of the ovaries), destruction of oocytes in all growing follicles, and depletion of resting follicles. The manufacturer of PZP as well as Bureau of Land Management (BLM) should have been aware of these and other findings about the pesticide. Yet they ignored or disregarded any information that was contrary to their personally-preferred but obsolete and false description of PZP’s mode-of-action.
PZP Manufacturer’s Own Research Found Markedly Depressed Estrogen Secretion
In a telling study published back in 1992, the manufacturer of Native PZP, along with colleagues, reported that ” … three consecutive years of PZP treatment may interfere with normal ovarian function as shown by markedly depressed oestrogen secretion.”  Thus, despite all the hype about PZP being non-hormonal, the manufacturer knew that ZonaStat-H has an adverse hormonal effect, causing significantly-lowered estrogen. Thus, PZP is an endocrine disruptor.  The plummeting estrogen-levels may also reflect the ovarian dystrophy and oophoritis now known to be caused by PZP. Despite personally discovering negative hormonal impacts 23 years ago, PZP’s manufacturer continued to cite misinformation regarding the product’s mode-of-action and endocrine-disruptor side-effects.
PZP Causes Ovarian Cysts
In their 2010 meta-analysis, Gray & Cameron cited a number of studies that found ” … alterations to ovarian function, oophoritis, and cyst formation with PZP treatment (Mahi-Brown et al.1988, Sehgal et al. 1989, Rhim et al. 1992, Stoops et al. 2006, Curtis et al. 2007).”  These findings support those of Kaur & Prabha while introducing yet another adverse effect: ovarian cysts. Gray & Cameron’s review also noted that increased irritability, aggression, and masculine behavior had been observed in females following PZP-treatment.
PZP → Endocrine Disruptor → Elevated Testosterone → Masculinizing Effects
Recall that PZP has endocrine-disrupting effects that result in lowered estrogen. Per the observed masculine behavior of treated mares, PZP seems to have a testosterone-elevating effect too. A deficit of estrogen alone would not necessarily manifest in the masculinization of treated females, but an excess of testosterone would. So, it appears that PZP disrupts at least two hormones: estrogen — by substantially lowering it — and testosterone — by substantially elevating it. Adverse effect: Unnatural behavior.
PZP → Ovarian Cysts → Elevated Testosterone → Masculinizing Effects
As discussed above, PZP correlates with abnormal masculine behavior on the part of treated females, a side-effect likely due to elevated testosterone. But in addition to the endocrine-disruption caused by PZP, there could be a second way for testosterone levels to become elevated. Recall that PZP causes ovarian cysts. An Internet search on “ovarian cysts and testosterone” yielded results for polycystic ovary syndrome (PCOS) in women. Interestingly, one of the symptoms of PCOS is high testosterone levels. [12 and 22] The connection between ovarian cysts and elevated testosterone suggests that the ovarian cysts caused by PZP could — either alone or in combination with PZP’s endocrine-disruptor effects — lead to high testosterone levels in treated females, as evidenced by their masculinized behavior.
PZP Causes Additional Adverse Effects
Gray & Cameron’s review also disclosed that, when PZP was administered to the females of a herd, males lost body condition while the oft-claimed improvement in female body condition did not hold up. Further, mares remained sexually active beyond the normal breeding season and had more estrus events.
PZP Selects for Weak Immune Function
Gray & Cameron’s analysis raised the possibility of PZP selecting for immuno-compromised individuals. Here’s why. Because PZP stimulates the immune system, it ironically works “best” — sterilizes faster — in mares that have strong immune-function. Such mares respond to the anti-vaccine and produce quantities of PZP antibodies that destroy their ovaries. But, conversely, PZP may not work at all in mares whose immune-function is weak or depressed. Those mares fail to respond to PZP. They keep getting pregnant and producing foals who, like their dam, suffer from weak immune-function. So, the PZP pesticide works against the very horses that Nature has best equipped for survival against disease while favoring and selecting for the immuno-compromised. Thus, a herd being treated with PZP is undergoing selective breeding for weak immunity, which puts the population at risk for disease — and ultimately, for extinction.
PZP Confers Dubious “Benefit” of Increased Longevity
Gray & Cameron also cited a study that found that “… PZP treated feral horse mares lived longer, resulting in a new age class (>25 years) not present before treatment ….” Exceptionally-long life is an ironic effect of PZP treatments. PZP’s manufacturer actually boasts about it, as if the anomaly were a good thing. However, Gray & Cameron questioned the supposed benefit of mares living much longer than their normal life expectancy. Indeed, such mares take up scarce slots within size-restricted populations. The ultra-elderly mares continue to consume resources for many years, but they no longer contribute to the gene-pool. It is detrimental to a population’s genetic viability to carry significant numbers of sterile herd-members way-beyond their normal life-span.
Research on Wildlife Contraceptives Revealed Stillbirths and Auto-Immune Oophoritis from PZP
There was an even earlier, definitive meta-analysis on wildlife contraceptives. Nettles (1997) reviewed 75 studies available at that time on the subject. Among his findings regarding PZP-use across different species, including horses, were: Stillbirths; altered ovarian structure and cyclicity; interference with normal ovarian function; permanent ovarian damage; and some cases of irreversible sterility due to auto-immune oophoritis, which suggested that PZP can be selective against a certain genotype in a population.  Many of these findings were confirmed by Kaur & Prabha as well as by Gray & Cameron. Please keep in mind these key findings: Stillbirths, and auto-immune oophoritis.
Recent Stillbirths Correlated with PZP
There is recent evidence confirming Nettles’ finding of a correlation between PZP treatments and subsequent stillbirths. In June 2015, Karen Sussman, President of the International Society for the Protection of Mustangs and Burros, reported that 7 mares previously treated with PZP at ISPMB, when taken off PZP, were able to get pregnant. However, 6 of those 7 mares — that is, 86 percent — produced foals that were stillborn. All other ISPMB mares that had not been injected with PZP successfully birthed healthy foals. Thus, given that environmental and other conditions were identical, the only variable was PZP. The dead foals have been sent to a university pathology department for autopsy. 
Autoimmune Oophoritis Induced by PZP
Research by the Rose-Cihakova-Caturegli Laboratory at Johns Hopkins Pathology found: “Automimmune oophoritis can be induced by immunization with testis and ovarian antigen murine human zona pellucida 3 peptide (pZP3) in adjuvant.”  Here again, is causation of autoimmune disease by a ZP-type product. This finding confirms other research cited herein.
Autoimmune Oophoritis and Risk of Other Autoimmune Diseases
A study by Varras et al. disclosed that, in humans, autoimmune oophoritis carries the risk of the patient developing other autoimmune diseases.  The correlation between autoimmune oophoritis and subsequent other autoimmune disorders weighs against injecting fillies and mares with PZP repeatedly and en masse.
Prolonged Breeding Season, Unusually-late Parturition Dates with PZP
Nettles’ meta-analysis on PZP disclosed other adverse effects: A prolonged breeding season and unusually-late parturition dates. (Parturition is the formal term for “giving birth.”) These findings have recently been confirmed, as is discussed below.
Parturition-Season Extends to Nearly Year-Round When a Herd Is Treated with PZP
A longitudinal study (Ransom et al. 2013) of three herds currently being managed by PZP — Little Book Cliffs, McCullough Peaks, and Pryor Mountain — found that the the parturition season lasted 341 days.  Ransom et al.’s finding of a nearly year-round birthing season supports the earlier finding by Nettles. Thus, during its period of potential reversibility, PZP’s effects wear off unpredictably. Out-of-season births put the life of both the mare and the foal in jeopardy. Nature designed the equine birthing-season to occur in Spring, not year-round, and certainly not in the dead of Winter.
Prolonged Delay in Recovery of Fertility
The same longitudinal study by Ransom et al. found that, after suspension of PZP, there was a delay lasting 411.3 days (1.13 years) per each year-of-treatment before mares recovered their fertility. What this means is that it takes that long, on average, for the ovaries to heal, to clear out all those cysts, and to regain some degree of normal hormonal function.
The question is: How is the delay in recovery-of-fertility addressed by BLM management practices? Answer: BLM ignores it. For instance, BLM currently administers PZP to Pryor Mountain’s fillies and mares starting at age 1½ — whom BLM artfully describes in the Environmental Assessment as fillies “becoming two year olds” — through age four. Thus, these fillies and mares receive intentional treatments for four consecutive years before being allowed the privilege of reproductive potentiality. Per Ransom et al.’s study, the Pryor Mountain fillies and mares would be expected to need 1,645.2 days (4.51 years) to regain reproductive capacity. But BLM gives the Pryor Mountain mares only 5 years off PZP before they are put back on it again — for the rest of their life. Thus, these fillies and mares might have just a six-month window — at best — in which to conceive. Due to the unpredictable timing of PZP’s wearing off, for some mares that window of fertility will close before they get a chance to produce a foal. Those mares’ genetic contribution will be zero.
As if the above scenario were not bad enough, PZP’s manufacturer conceded that it could take up to eight years to recover fertility after just three consecutive PZP treatments. 
Ransom Advises Proceeding with Caution regarding PZP
The Ransom et al. study warned: “Humans are increasingly attempting to manage the planet’s wildlife and habitats with new tools that are often not fully understood. The transient nature of the immunocontraceptive PZP can manifest into extraordinary persistence of infertility with repeated vaccinations, and ultimately can alter birth phenology in horses. This persistence may be of benefit for managing overabundant wildlife, but also suggests caution for use in small refugia or breeding facilities maintained for repatriation of rare species.” 
Because BLM keeps over 70 percent of the herds at levels below minimum-viable population (MVP), most herds qualify as “small refugia.” Pryor Mountain WHR is a small, isolated refuge, and its wild horses carry genes with rare alleles.
Ransom’s Exclusion of Seven Mares Evidences PZP’s Non-Effect on Immunocompromised Mares
In the “Data Collection” methodology section of the Ransom et al. report, the authors advised: “We omitted data for one female from the Little Book Cliffs and six females from McCullough Peaks because they produced offspring in every treatment year and thus were never effectively contracepted.”
This fact is important because it evidences PZP’s lack-of-efficacy on immunocompromised fillies and mares. To review: Because PZP activates the immune system, mares with naturally-low or depressed immune function do not “respond” to the treatment. It’s as if they had been injected with saline — their immune system is so weak that it does not react to the PZP by producing antibodies. The good news is such mares’ ovaries are saved from PZP’s destructive effects. The bad news is that these mares continue to become pregnant year after year, producing foals that will also tend to inherit low immune-function. Over time, the herd will become populated with more such low-immune horses because those with strong immunity get sterilized. Thus, PZP selects for horses with low immune function, which is bad for a herd in the long term. Even a routine infection could spread quickly and wipe out a population of horses with weak immune-function. If the goal is to preserve a herd, the use of PZP constitutes a worst management-practice.
BLM Was Fully-Aware of the Ransom Study but Suppressed the Findings
In their report, the authors of the Ransom et al. study gave a shout-out to BLM “for administrative and technical support throughout this project.” Thus, BLM was fully aware of the multi-year study while it was in progress and even lent support to it administratively and technically. Yet, in the case of the Pryor Mountain herd, BLM omitted this important report as a reference for the 2015 Environmental Assessment, which proposed intensifying the PZP “prescription.” Thus, BLM pretended that there was no such report and unethicallly suppressed it. Consequently, the public could not comment knowledgeably and appropriately on the continued use of — let alone the accelerated application of — PZP.
Three PZP Injections Can Trigger Sterility in Mares, or Just One Shot in Fillies Before Puberty
Disturbingly, another recent study on PZP (Knight & Rubenstein, 2014) found that ” … three or more consecutive years of treatment or administration of the first dose before sexual maturity may have triggered infertility in some mares. 
These findings are particularly troubling. They suggest that, actually, only two consecutive PZP-treatments may be reversible. Except, that is, in the case of fillies who have not yet reached puberty — they could be sterilized by just one injection. Recall the Pryor Mountain fillies, whose PZP treatments begin when they are just 1½ years old. They may not have reached puberty when they are initially treated.  And as we shall see later in this report, that first shot of PZP may not be their first shot of PZP.
Researchers Again Express Concerns about the Abnormal Life-Spans of Sterilized Mares
Knight & Rubenstein warned: “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.”
Knight & Rubenstein’s concerns support those of Gray & Cameron, who also questioned the supposed benefit of sterile mares’ extended life-spans. The abnormal numbers of aged, sterile mares count for census-purposes; but their presence disadvantages the younger horses, who become tageted for removal in order for BLM to achieve arbitrary management levels. Further, such mares no longer belong to the viable gene-pool.
PZP’s Destructive Antibodies Are Transmitted via the Placenta and Mother’s Milk
It gets worse. Sacco et al. reported that, per radioimmunoassay, PZP antibodies are transferred from mother to young via the placenta and milk. The transferred antibodies cross-react with and bind to the zonae pellucidae of female offspring, as demonstrated by immunofluorescent techniques.  These findings were disclosed in 1981. PZP’s manufacturer must have known about this dangerous effect, and certainly BLM should have investigated on its own whether there was any risk to the unborn or the nursing foal. Yet, the manufacturer continued to insist that there was no danger to the foal, whether born or unborn. [7 and 13] And in fact, BLM regularly administers PZP to pregnant and lactating mares, who transfer the destructive antibodies to their fetus, via the placenta, and to their foal, via mother’s milk.
Recall again the Pryor Mountain fillies. If their dams were injected with PZP while pregnant or nursing, such fillies will already have PZP antibodies cross-reacted with and bound to their zonae. Therefore, when those same fillies are injected at age 1½, it will be their second treatment, or potentially even their third. In fact, they could already have been sterilized in utero or while nursing, the treatment having been received prior to puberty, about which Knight & Rubenstein warned.
PZP Weakens Herd-Immunity, Posing Risk of Stochastic Events Leading to Herd-Extinction
To be self-sustaining, a herd needs to possess good immunity to withstand random catastrophes — known as stochastic events — such as contagious infections. There was such an event recently in Kazakhstan, where 120,000 endangered Saiga antelope — half the world’s population — died off suddenly and inexplicably within a two-week period. Scientists think a common bacterial infection was the cause of this mass-mortality event, but are unsure why the antelope were unable to fight off the disease immunologically. 
Imagine if such a catastrophe were to befall the Pryor Mountain horses, whose herd-immunity is being eroded by PZP. Note that the Saiga deaths involved antelope-mothers and their calves. If Pryor Mountain’s few fertile mares and their foals perished all of a sudden, that would leave just stallions and sterile old mares. The herd would be composed of the living dead, reproductively speaking, its rare alleles extinguished. BLM is failing to proactively manage the Pryor Mountain herd with stochastic events taken into consideration. That is malfeasance. PZP is a tool of immunological destruction, not of proper management.
PZP Continues the Use of Roundups and Removals
If the promise of PZP were true — if PZP really did eliminate the need to remove “excess” wild horses from the range — removals would have ended long ago in the Pryor Mountain Wild Horse Range, where PZP has been in use for approximately two decades. Yet removals are scheduled there with regularity every three years, the latest one in 2015.
Risks to Humans Who Administer PZP Injections
For staff and volunteers who inject wild horses with PZP, EPA’s Pesticide Fact Sheet advises that Personal Protective Equipment requirements include long sleeved shirt and long pants, gloves and shoes plus socks to mitigate occupational exposure. EPA specifically warns that pregnant women must not be involved in handling or injecting ZonaStat-H, and that all women should be aware that accidental self-injection may cause infertility. 
However, EPA’s Fact Sheet, the manufacturer’s training, and BLM’s operating procedures fail to inform pregnant women why it is so important that they strictly avoid PZP — because PZP’s antibodies cross the placenta and cross-react with and bind to an unborn female child’s own little zonae pellucidae. The baby-girl could be “anti-vaccinated” with PZP and even sterilized before birth.
EPA’s Fact Sheet, the manufacturer’s training, and BLM’s operating procedures fail to warn lactating women to avoid PZP and why — because PZP’s destructive antibodies would be passed along to a nursing female child via mother’s milk. The baby-girl could be “anti-vaccinated” with PZP and possibly sterilized simply from nursing.
EPA’s Fact Sheet, the manufacturer’s training, and BLM’s operating procedures fail to warn all women of the risk of ovarian dystrophy, oophoritis, ovarian cysts, and elevated testosterone-levels — in addition to infertility and, potentially, sterility — from unintentional self-injection.
EPA’s Fact Sheet, the manufacturer’s training, and BLM’s operating procedures fail to emphasize the magnitude of the risk — the PZP-in-question is a horse-size dose.
But Is There a Mandate to Practice Scientific Integrity?
Yes. The Department of the Interior’s (DOI) Code of Scientific and Scholarly Conduct applies to all staff members as well as to contractors, partners, permittees, and volunteers. The Code states: “Scholarly information considered in Departmental decision making must be robust, of the highest quality, and the result of as rigorous scientific and scholarly processes as can be achieved. Most importantly, it must be trustworthy.” 
BLM has ignored and suppressed independent scientific findings about PZP’s adverse effects and unintended consequences. Instead, BLM continues to rely almost exclusively on the manufacturer’s claims — shown and known to be false — regarding PZP’s safety for use on horses and for handling by humans. BLM is thus non-compliant with the Policy and malfeasant in its responsibilities to protect staff, volunteers, and the wild horses under its jurisdiction. BLM is also misleading and disinforming Congress and the American public about the PZP pesticide.
The manufacturer of PZP — a partner to BLM — misrepresented the pesticide as safe for use on animals by humans. The manufacturer knew or should have known that the former hypothesis regarding PZP’s mode-of-action had been disproved, and that PZP has dangerous side effects, safety-issues, and unintended consequences. Yet he hid and denied that information and failed to warn about PZP’s adverse effects. The manufacturer cited his own research as if it were definitive, and aggressively criticized independent researchers whose findings did not fully support his claims. Indeed, he recently submitted an Op-ed to The Salt Lake Tribune wherein he belittled the research of fellow scientists whose studies on PZP yielded results somewhat different from his own.  His accusations were so unreasonable that the scientists felt it necessary to submit an Op-ed in response to defend the integrity and validity of their work.  The manufacturer also disparaged members of the public — one of whom was a member of the Pennsylvania Game Commission — who expressed concerns about PZP. He dismissively accused them of “an attempt to mislead,” of “hyperbole,” of “knowingly manipulating information,” of “attempts to frighten people,” and of indulging in an “anti-intellectual approach to debates.”  By these actions, the manufacturer violated the DOI’s Code of Scientific and Scholarly Conduct.
PZP Manufacturer Misled Trainees into Believing that PZP Was Safe
BLM staff and volunteers receive their training from PZP’s manufacturer in how to handle and administer the pesticide. BLM is remiss in delegating the training to the manufacturer without verifying the adequacy of the instruction and the truthfulness of it. Two comments recorded recently in the media suggest that PZP’s manufacturer misled not just the public-at-large but those who received training therefrom in how to administer PZP.
First, the manufacturer has been quoted as saying that PZP is “so safe it is boring.”  Independent research shows otherwise — that PZP is a powerful hormone disruptor that could sterilize a female with just one injection. If trainees believe that PZP is boringly safe, they will be less likely to protect themselves adequately from this dangerous pesticide. Indeed, many of the trainees are women and, therefore, particularly at risk. Likewise, wild-horse advocates are lulled into complacency, trusting that PZP is harmless to the Pryor Mountain horses and their rare genetic alleles. Of course, none of that is true.
Second, a PZP supporter, who self-identified as a recent completer of the PZP-darting training program conducted by the manufacturer, said in a comment posted to a news article: “I just received my FDA certification to handle and administer Native PZP. Would you be so kind to provide a link to the study you keep referencing? To my knowledge, and those teaching the Native PZP certification class, there are no side effects of the PZP produced by Dr. Kirkpatrick and his team, which is Native PZP.”  Key words: “no side effects.” It is disturbing that a person who was, no doubt, motivated by a desire to help the horses has been disinformed regarding PZP’s safety-hazards to humans as well as to horses.
BLM Fails to Maintain Proper Supervision of the PZP Volunteers
The issue of safety is not the only concern. As BLM has admitted, volunteers darted the wrong mares on Pryor Mountain. These errors evidence that BLM has failed to maintain supervisory control over the volunteer-inoculators, allowing them to conduct the PZP-darting by themselves. The mistakes further evidence that the volunteers do not understand what is expected of them. Who can say whether other procedures were not complied with either. The fact that mares were darted who were ineligible for PZP per the then-current protocol, but who would be eligible under the proposed-but-not-yet-promulgated new “prescription,” suggests that the volunteers may have concluded — from BLM’s open contempt for the Constitution and disrespect for the NEPA process — that was okay for them to start darting otherwise-ineligible mares right away. Not surprisingly, BLM blames the volunteers for these mistakes, but probably has not informed them that they are being made to take the rap for management’s shortcomings.
PZP is appropriately categorized as a pesticide by the EPA. PZP “works” by tricking the immune system into attacking and destroying the ovaries. PZP has many adverse effects as well as unintended consequences. PZP presents safety-hazards to humans who handle it. PZP is a dangerous pesticide whose use is antithetical to the spirit and intent of the Wild and Free-Roaming Horses and Burros Act. BLM’s continuing to use PZP while ignoring and suppressing the evidence of its harmful effects constitutes malfeasance.
This report was completed by Marybeth Devlin on December 24, 2015. Copyright Marybeth Devlin and Protect Mustangs 2015.
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Education is important when there is so much spin out there selling PZP as the drug to end roundups/slaughter. Read what Wikipedia says http://en.wikipedia.org/wiki/Immunocontraception
Be sure to visit the Forum on PZP at Facebook for a lot of information: https://www.facebook.com/groups/ForumPZPWildHorsesBurros/
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Does PZP result in wild herds with lower immune systems and potential for die-offs?
PZP is an immunocontraceptive and pesticide which causes an immune reaction to reject fertilization, while the females still come into estrus. Besides wrecking havoc on the immune system, injecting herds with PZP results in more fighting between males and many other behavior abnormalities. Tule elk in … Continue reading
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Lies, subterfuge and PZP
By, Carl Mrozek Unfortunately, the secret mandate to turn our public lands into vast oil, gas and coal fields–interspersed with millions of cattle under Bush–Cheney has continued unabated under Obama with geothermal fields, plus solar and wind farms being added …Continue reading
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Fear of sterilization used to push PZP on free roaming wild horses
BLM’s plans for sterilization include the slow extinction drug called PZP which sterilizes after multiple use Since 2009 and surely earlier, the Bureau of Land Management (BLM) has always said they want to sterilize wild horses and burros. BLM and … Continue reading
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Protect Mustangs is an organization who protects and preserves native and wild horses.