Perverted Darting with Pesticide PZP

10 things you need to know about Pesticide PZP

1. PZP — The Pesticide: PZP is an EPA-registered pesticide manufactured from the ovaries of slaughtered pigs. Some persons argue that, because PZP does not kill the mare, it is not really a “pesticide.” Actually, PZP does kill. Stillbirths are associated with the pesticide’s use, meaning that some of its supposed contraceptive effects are actually feticidal.. In addition, over the long term, PZP weakens a herd immunologically, putting it at risk for eventual or even sudden extinction.

2. PZP — The Disproved Hypothesis: PZP’s manufacturer promoted the product as generating antibodies that “block sperm attachment.” But that marketing-hype was merely an untested hypothesis postulated three decades ago. Independent researchers found that PZP has a different effect, and many adverse effects.

3. PZP — The Actual Mode-of-Action: Behaving like a perverted vaccine, PZP tricks the mare’s immune system into making antibodies that cause ovarian dystrophy, autoimmune oophoritis, ovarian cysts, and premature ovarian failure. PZP quickly sterilizes mares that have a strong immune system but has no effect on those suffering from weak immunity. Thus, PZP both works and doesn’t work but, in the long run, selects for poor immune function. Weak immunity = weak resistance to infection, which could quickly wipe out a herd. PZP also affects the foals. If a mare is pregnant or nursing when darted, PZP antibodies are transferred to her offspring via the placenta and her milk. So, inadvertently, unborn and newborn foals receive a dose or two of the pesticide when their dams are injected.

4. PZP — The Danger to Humans: PZP is a powerful endocrine-disruptor. It causes a sharp drop in estrogen levels. Unfortunately, because the manufacturer misrepresented PZP as “so safe it is boring,” volunteer-darters have become lax in following safety-precautions. Accidental self-injection could result in severe adverse effects because the dose-in-question is sized for a horse.

5. PZP — The Year-Round Birthing-Season: A longitudinal study (Ransom et al. 2013) of three herds currently under treatment with PZP found that the the birthing-season lasts virtually year-round (341 days). Out-of-season births put the life of mares and their foals in jeopardy. Nature designed foals to be born in Spring, not year-round, and certainly not in Winter.

6. PZP — Prolonged Delay in Recovery of Fertility: Ransom et al. also found that, after suspension of PZP, it takes more than a year per each year-of-treatment before mares recover their fertility. PZP’s manufacturer conceded that it could take up to 8 years to recover fertility after just 3 consecutive years of PZP treatment.

7. PZP — Scientists Say Proceed with Caution: Ransom et al. warned: “The transient nature of … PZP can manifest into extraordinary persistence of infertility with repeated vaccinations, and ultimately can alter birth phenology in horses. This persistence … suggests caution for use in small refugia ….”

8. PZP — Contraindicated for Tiny, Isolated Herds: Several years ago, BLM convened a meeting of scientists on the topic of minimum herd-size for genetic fitness. Conclusion: “Smaller, isolated populations (<200 total census size) are particularly vulnerable ….” And that’s without PZP in the mix.

9. Slow Herd-Growth: Per independent research, wild-horse herds increase at a rate of only 5% a year; and wild-burro herds, just 2%. Such slow growth does not warrant pesticide treatments administered en masse every year. Eventual sterilization is inevitable, with extinction of the herd over the long term.

10. Predators: The right way to right-size the wild-horse population is Nature’s way — predators. But those predators — mountain lions, bears, wolves, and coyotes — are persecuted mercilessly. Wildlife Services exterminates what trophy-hunters don’t shoot. Predators help the herds by favoring survival-of-the-fittest and the best genetic adaptations. Predators are the “no-cost” solution.

by Marybeth Devlin
Wild Horse Advocate

This mare waits in the alley before being led into the chute where her age and body condition will be checked. After being treated with the PZP fertility control agent, this mare will be released back to the Owyhee HMA.

Protect Mustangs is a 501(c)3 nonprofit organization dedicated to the protection and preservation of native and wild horses.

Conflict of interest, wild burros and pesticide PZP


(Photo Credit Rylee Isitt/WikiCommons)

Deadline extended to August 22, 2016 so please get your comments in. Below is what Marybeth Devlin sent in. 

Postmarked or Received by:

August 15, 2016



State Office

Colorado River District Office

Kingman and Lake Havasu Field Offices

Copies to:

CEQ, DOI, and BLM National Office

with hard-copy via Priority Mail to:

Bureau of Land Management

Kingman Field Office

2755 Mission Boulevard

Kingman, AZ  86401

Subject: Black Mountain Wild Burros

Project: PZP Fertility-Management Pilot

Proposed by: Humane Society of the United States

Document: Environmental Assessment ( EA )

NEPA ID: DOI-BLM-AZ-C010-2016-0004-EA

This letter responds to the public-comment period currently underway regarding the management of the wild burros whose dedicated habitat is the Black Mountain Herd Management Area (HMA).  I submit these substantive comments — questioning the accuracy and integrity of BLM’s analysis — and new information relevant to the analysis that should have been considered but was not — as an interested party in behalf of the Black Mountain wild burros.  Please note that in all instances where text has been emphasized, either through bold and/or italics, the emphasis was added by me.  For ease of reference, below are the respective links to BLM’s press release and to the Webpage where the Dear Reader letter and the EA are posted.


The Proposal

BLM received an unsolicited proposal from Humane Society of the United States (HSUS) to conduct a pilot study on the use of porcine zona pellucida (PZP), also known as ZonaStat-H, an EPA-registered pesticide that induces infertility, on as many as 165 wild jennies of the Black Mountain herd.  HSUS would endeavor to determine the effects of PZP on individual jennies and on herd-structure following treatments.  HSUS would particularly focus on whether remote “opportunistic” retreatment methods could work.  HSUS would collect and maintain data-sheets, and submit them as well as an annual progress report to BLM for review.

HSUS has requested $33,695 in funding from BLM over 3 years.  BLM reviewed the proposal and has now issued a preliminary EA, accepting public comments before issuing a decision.

Captured and Held — Injected and Re-Injected — Branded and Disfigured

The jennies would be captured via bait-trapping and then transported to a holding facility for injection with PZP.  They would be held captive for the next several weeks in order to administer a second “booster” injection of PZP.  Most (70 to 100) of the jenny-subjects would also be freeze-branded with three digits on both hips for HSUS and BLM’s convenience in identifying them.  Such permanent freeze-marks are typically 3½ or 4 inches high, and the letters are wide.  Following the injections and branding, the jennies would be transported back and released into the HMA.

Annual Roundups Probable

Although field-darting would be attempted for the annual retreatments, the EA acknowledges that it might be necessary to bait-trap the jennies again for that purpose as well as in order to freeze-brand them a second time or to allow veterinary treatment of abscesses at the injection-sites.  Thus, program funds would be spent for rounding up the test-subjects yearly, and the costs thereof would be over-and-above the grant for which HSUS has applied to conduct its study.


HSUS — PZP’s Registrant

HSUS is a leading advocacy-organization for animal-welfare.  It provides leadership to advance the cause of humane treatment of animals.  In response to BLM’s abusive helicopter-roundups and scandals involving wild horses and burros being sold into slaughter, HSUS sought a compassionate way to manage the mustangs on the range.  It was a noble goal, and PZP was proffered as the answer.

PZP / ZonaStat-H was touted by its manufacturer as “so safe it is boring” [11] and its contraceptive effects, as reversible.  Relying on the manufacturer’s representations, HSUS applied to the Environmental Protection Administration (EPA) to have the product approved for use on wild horses and burros, which the EPA did — as a pesticide in cases where mustangs were deemed to have become a “nuisance.”  So highly respected was HSUS’ reputation, that EPA waived certain protocols that are normally required.  Unfortunately, HSUS failed to fully investigate the product beforehand, has not done so subsequently, and does not seem interested in knowing about any drawbacks to its use.  Consequently, HSUS is ignorant of the body of science weighing against PZP.

Now, HSUS is seeking to conduct a study of PZP on the subject herd of wild burros.  But because HSUS is the registrant of the pesticide PZP, a conflict of interest is apparent.  HSUS has a stake in the outcome of the proposed study, namely, to see it succeed and to ignore ill effects.  Lacking scientific impartiality, HSUS must be disqualified from studying its sponsored product and from using taxpayer money to experiment on America’s underpopulated wild burros.

BLM and HSUS — Rely on PZP’s Manufacturer for Safety Information

The EA relies heavily on reports issued by PZP’s manufacturer regarding product-safety and lack of adverse effects.  However, such data is suspect because the manufacturer has a stake in promoting its product.  Lacking scientific impartiality and having a financial interest in the outcome, the manufacturer has an apparent conflict of interest.  Therefore, independent studies should compose the majority of the references regarding the use of PZP; however, that is not the case.  Indeed, as will be addressed later in this letter, numerous independent studies have been conducted, and they revealed many adverse effects of PZP.

Mandate to Practice Scientific Integrity

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. [36]

BLM and HSUS have ignored and BLM has suppressed independent scientific findings about PZP’s adverse effects and unintended consequences.  Instead, BLM and HSUS continue to rely almost exclusively on the manufacturer’s claims regarding PZP’s safety for use on burros and horses, and for handling by humans.  In fact, independent research — and even one study by the manufacturer — disclosed that PZP is hazardous to burros, horses, and humans.  BLM and HSUS are thus non-compliant with the Policy and malfeasant in their responsibilities to protect staff, volunteers, and the wild burros and horses.


The rationale for using birth control on the Black Mountain burros is predicated on false assumptions — “virtually no natural predators” and “herd sizes can double nearly every four years” — and fraudulent figures — reported herd-growth numbers many times over the biologically plausible.  It is wrong to proceed when the premises-for-action are counterfactual and fraudulent.  In the EA, BLM attempts to separate the premises from the proposal; however, the two are inextricably linked.

False Premise #1 — Lack of Predators

Contrary to BLM’s assertion, burros do have natural predators: Mountain lions and coyotes.  Both species are present in Black Mountain HMA.  If BLM believes that inadequate numbers of these apex predators preventing them from fulfilling their population-control function, then BLM should take action to conserve them.  Collaborate with the Arizona Game & Fish Department (AGFD) to prohibit hunting of predators in the HMA, and negotiate with Wildlife Services, to stop that agency from killing them.  Put some healing balm on that “trigger itch” — as Aldo Leopold called it. [22]

Healthy Predators, Healthy Ecosystem

To achieve a “thriving natural ecological balance,” the Black Mountain HMA should be a safe-haven for predators.  Such an approach would help the burros by favoring survival-of-the-fittest and the best genetic adaptations, and by keep the herd-population in equilibrium with minimal human-interference, just as the Act envisioned.  Predators are the “no-cost” option.  Conservation Researcher Dr. Corey Bradshaw emphasizes just how important predators are to a healthy ecosystem:

Long story short – if your predators are not doing well, chances are the rest of the ecosystem is performing poorly.

Predators keep the ecosystem in balance.  Without them, prey species decline, as do the forage-production species on which the prey-animals feed.  Dr. Bradshaw warns: “Without predators, our feeble attempts to conserve ecosystems are doomed to fail.” [4]

Predator Reintroduction

Wolves also prey on burros.  However, Arizona’s wolves had been intentionally exterminated by the Federal and State governments to placate livestock-ranchers and to please trophy-hunters.  Both groups — ranchers and hunters — continue to oppose the wolves’ right-to-exist.  However, their reasons are self-serving.

Now that wiser minds have prevailed, initiatives to reintroduce wolves are ongoing. [22]  Mohave County does not yet appear to be participating in the Mexican Wolf Restoration Project.  However, again, if BLM believes there is a dearth of apex predators in the HMA, then reintroduction of Mexican Wolves is a logical solution.  Because the Federal government played a major role in the extermination of wolves, the moral imperative is for the Federal government — via BLM — to make restitution to the species.  The Black Mountain HMA could be designated a wolf-recovery area (WRA). [41]

False Premise #2 — High Reproductive Rate

First, some background facts.  Burros are a slow-growth species when it comes to reproduction. The gestation-period lasts an average of 12 months — although it can extend as long as 14 months.  A jennet produces just 1 foal, and she typically reproduces in alternate years.  Further, the conception-rate of jennies is lower than that of mares.  Thus, in contrast to wild-horse herds, wild-burro herds grow more slowly. [1, 31 and 46]

BLM uses a standard, assumed burro birth rate — 15% — as a proxy for the herd-growth rate.  However, for a herd-growth rate to be valid, the birth rate must be adjusted by the death rate.  To wit, …

Herd-growth rate Birth rate

Herd-growth rate = Birth rate Foal death rate Adult burro death rate

As is evident, BLM incorrectly equates births with herd growth.  BLM wrongly assumes that all foals survive and that all adult burros live forever.

BLM’s assumption regarding burro-foal survival has been falsified per a recent independent review of BLM records.  Gregg, LeBlanc, and Johnston (2014) found a high mortality rate for newborn burro-foals.  Their study concluded that, based on survival-data from birth-to-yearling status, the effective increase in a typical burro-population attributable to new foals is just 7%. [13]

However, adult mortality must also be taken into consideration when estimating herd-growth.  Adult wild burros succumb to illness, injury, and predation.  Others are shot and killed by unethical parties.  Still others perish from stochastic events — random catastrophes such as an epidemic or a wildfire.  Adult wild burros are believed to have a mortality rate of at least 5% a year.

So, what is a normal herd-growth rate among wild burros?  A good estimate would be about 2%, probably less.  Thus, a burro herd could not double in 4 years, debunking yet another false premise held by BLM.

Fraudulent Numbers

BLM’s press release starts off by announcing that there are 5,000 wild burros in Arizona.  The inescapable purpose of citing a state-level population instead of the subject herd’s population — which is the only one under analysis for the EA — is to prejudice the public against the burros, to “build a case” that the burros are seemingly “overpopulated.”  Such manipulation of the numbers evidences lack of scientific integrity on the part of BLM staff.

Figure 2 of the EA purports to show, in visual format, how “unchecked herds double in size every 4 years.”  Figure 2 is just another fraud perpetrated by BLM at the National level and now copied at the Field Office level.  It is disinformation — propaganda, not science.  Independent research and analyses have revealed that BLM falsifies its wild-horse-and-burro population-data.

Fraudulent Estimates

A review of BLM’s population-estimates for the Black Mountain herd disclosed biologically-dubious year-to-year growth data.  The figures reflect herd-growth way beyond the normative foal-survival rate, and adult mortality was evidently ignored. [40]

The chart below tracks BLM’s reported herd-growth estimates for the Black Mountain burros since 2013, which serves as the base, the starting point — assuming it is correct, which is probably not the case.  Deviations from three norms are calculated:

(1)  From BLM’s assumption of a herd-growth rate of 15%, which does not take mortality — either foal or adult — into account;

(2)  From the Gregg et al. study of BLM records, which found a 7% increase in burro herds attributable to new surviving foals but which did not take adult-mortality into account; and

(3)  From the Gregg et al. study’s finding of a 7% increase due to new surviving foals, but adjusted to take into account a conservative annual adult-mortality rate of 5%, which yields a net herd-growth rate of 2%.

    (1)     (2)     (3)


from 15% from 7%             from 2%

per BLMper Studyper Study

without without with 5%

Foal orAdult Adult

PopulationGrowthAdult Mortality Mortality

Year Estimate Rate Mortality

2013   800   n/a    n/a    n/a    n/a

2014 1,000   25%   67% higher 257% higher 1,150% higher

2015 1,450   45% 200% higher 543% higher 2,150% higher

2016 1,551     7%   53% lower   0% equal   250% higher

Note that the implausible growth rates compound, as each successive year is calculated per those that preceded it.  The errors compound also, leading to population-figures that are biologically impossible, given the reproductive limitations of the burro species.

Arbitrary Management Level (AML)

The AML for the Black Mountain herd was set in 1996 at 382 to 478 wild burros.  Black Mountain HMA comprises 925,425 acres, or 1,446 square miles.  Thus, per the AML, BLM implies that each burro needs 1,936 to 2,423 acres, or about 3 to 4 square miles per burro.

That idea that every little burro would need 3 or 4 square miles of range is preposterous as well as unscientific.  Therefore, the AML is arbitrary and capricious.

Minimum Viable Population (MVP) — IUCN Says ~ 2,500

The AML must be reformed to set a baseline — a starting point — of at least 2,500 burros.  Where does this number — 2,500 — originate?  It is the recommendations of the International Union for Conservation of Nature (IUCN), the world’s oldest and largest global environmental organization.  The IUCN is a neutral forum for practical solutions to conservation challenges and a leading authority on the preservation of genetic diversity in wild equids, including horses and burros.  The IUCN notes that the selective pressures wild equids have endured in the wild are likely shaping them genetically to be hardy stock that could prove useful as a genetic resource. [8]

Note that 2,500 is not a maximum but a minimum size.  Higher numbers would be better.  Because neither the questioned population-estimate nor the present AML reaches the minimal threshold of 2,500 individuals, the herd is under-populated.  Therefore, the Black Mountain HMA needs to have its herd-size baseline expanded accordingly.

By increasing the AML, the HMA would be brought into compliance with scientific expertise concerning adequate herd size.  The properly-set AML would be foundational to BLM’s best management practices (BMPs) relative to protecting and preserving this wild burro herd.

Minimum Viable Population (MVP) — Meta-Analysis Says ~ 5,000

Just when you think the answer to MVP has been found, a newer study is published. Traill, Bradshaw, and Brook (2007) conducted a meta-analysis of the scientific literature spanning the preceding 30 years on the topic of MVP. [35]  The researchers filtered hundreds of studies and selected 141 sources covering 212 unique species whose distribution was skewed toward heavier animals, particularly mammals. The researchers found:

Across all species, the median MVP was 4,169.  The “bootstrapped 95% confidence bounds” MVP for all species ranged from 3,577 to 5,129.

With regard to mammals, the median MVP was 3,876.  The “bootstrapped 95% confidence bounds” MVP for mammals ranged from 2,261 to 5,095.

Their conclusions:  In general, conservation practioners should aim for an MVP of approximately 5,000.  Specifically, the authors state: “… we recommend the upper 95% confidence limit of MVP ….”  For all species and for mammals specifically, a round number — a numerical threshold — of approximately 5,000 can be used to inform conservation management practices.

A 2010 article in American Scientist discussed the meta-analysis’ findings and provided some additional information gleaned from an interview with the lead author. [5]

How Would the New Levels Look?

Here are some numbers to compare and contrast.

Black Mountain HMA

Size:  925,425  total acres

Current Maximum Management Level:   478  wild burros

Acres per burro:  1,936

Current Exaggerated Population Estimate: 1,551  wild burros

Acres per burro:     597

IUCN Minimum Herd Size: 2,500  wild burros

Acres per burro:     370

Meta-Analysis Minimum Level for Mammals: 5,000  wild burros

Acres per burro:     185

Genetic Health of the Black Mountain Burros

In order to make informed decisions and to manage responsibly, BLM must have specific genetic data on each member Black Mountain burro herd.  Therefore, BLM needs to conduct a 100-percent evaluation of the Black Mountain burro-herd’s genetic health.  This would be accomplished by taking DNA samples and sending them in a timely manner to the Equine Genetics Lab.  Per the test-results, and per guidance from Dr. Gus Cothran and other equine experts, BLM must then reform the AML and develop best management practices to restore and maintain gene-pool diversity via a robust population-level.

The AML must ensure an optimal burro-population — one that can easily self-sustain its diversity and viability, and that can bounce back from random catastrophic events.

The correct sampling approach and order are:

Sample current and continuing herd members.

Sample first, before considering any actions.

Sample large — 100 percent.

Test samples.

Manage per test-results and best-available science.


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 ….” [38]

Some persons argue that, because PZP does not kill the mare or jenny, it is not really a “pesticide.”  Actually, PZP does kill.  As will be documented herein, PZP’s use is associated with stillborn foals.  PZP is further correlated with stolen foals and out-of-season foals, who perish as neonates.  In the long term, PZP tends to 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 could be viewed as an anti-vaccine.

PZP’s Mode of Action as Stated in the Pesticide Registration Is a Disproved Hypothesis

HSUS, the registrant of PZP advised the Environmental Protection Agency 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. [11 and 19]  HSUS is remiss in not investigating PZP beyond the manufacturer’s claims before touting it as the solution to the non-existent burro-overpopulation “problem.”  BLM is irresponsible in ignoring research that has disclosed PZP’s risks.

PZP’s True Mode-of-Action

So how does PZP really work?  PZP tricks the immune system into waging immunological 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.” [16]  [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, destruction of oocytes in all growing follicles, and depletion of resting follicles.  The manufacturer of PZP as well as 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.

Kaur & Prabha warned that “… long term studies showed that immunization with zona antigens might induce immunological attack on many eggs in the ovary which might lead to premature ovarian failure.”

Included as a reference to the EA?  No.

EA Lists Older PZP Study, but not Newer One by Same Scientists Showing Ovarian Pathologies

One of the references cited in the EA was a study by Curtis, Pooler, Richmond, Miller, Matfield, and Quimby (2002) on the comparative effects of GnRH and PZP on white-tailed deer.  However, the HSUS proposal would only examine PZP, not GnRH; so the Curtis et al. (2002) study would not be the most appropriate reference to use, especially in view of the fact that lead-researcher Curtis, along with most of the same colleagues — Richmond, Miller, and Quimby — issued a newer study (2007) on PZP alone.

The Curtis et al. (2007) study disclosed that 75% of PZP-treated white-tailed deer — and 50% of re-treated deer — suffered eosinophilic oophoritis (inflammation of the ovaries).  Further, the re-treated deer that did not develop oophoritis had a different problem — significantly fewer normal secondary follicles than control females.  The study-authors concluded that PZP “elicited ovarian pathologies in deer similar to those observed in other species.” [7]

PZP Manufacturer’s Own Research Found Markedly Depressed Estrogen Secretion

In a telling study, Kirkpatrick, Liu, Turner, Naugle, and Keiper (1992a), the lead author and 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.” [17]  So, 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. [39]  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 24 years ago, PZP’s manufacturer continued to cite misinformation regarding the product’s mode-of-action and hid its endocrine-disruptor side-effects.

Included as a reference to the EA?  No.

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).” [12]  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.

Included as a reference to the EA?  No.

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: Abnormal 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. [26 and 42]  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 boasted 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:


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. [23]

Many of these findings were confirmed by Kaur & Prabha as well as by Gray & Cameron.  The focus now turns to certain of these key findings: Stillbirths, and auto-immune oophoritis.  However, in discussing the correlation between stillborn foals and PZP-use, a related abnormality will be addressed: Stolen foals — abducted by barren mares treated with PZP.

Included as a reference to the EA?  No.

Stillborn Foals — 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 (ISPMB), 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. [33]

Included as a reference to the EA?  No.

Stolen Foals — Dominant Mares Treated with PZP Steal Foals from Young Mares

Ms. Sussman of ISPMB further reported that several mares that are barren due to PZP treatments have stolen — and continue to steal — foals from first-time-mother mares. [34]  Although the kidnappers do care for the foals tenderly, they have no milk.  Consequently, the foals starve unless ISPMB discovers the “crime” and can intervene in time to save them.  However, when such stealing occurs on public lands, there is no one to rescue the foals. So, it is likely that PZP kills foals indirectly — by their being kidnapped by barren PZP-treated mares, further confirming its status as a pesticide.  We can also infer that PZP’s population-reduction effect is probably due, in part, to foal deaths.

Included as a reference to the EA?  No.

Why Do PZP-Treated Mares Steal Foals?

Ms. Sussman has observed that the PZP-treated mares appear to suffer psychologically from their barrenness.  They seem unhappy and frustrated that they don’t have foals of their own.  So, they steal foals to fulfill that unmet maternal need.

Foal-stealing is yet another behavioral abnormality associated with PZP-use.  Thus, PZP wreaks havoc beyond just the individual mares treated with it, disrupting the life of non-treated mares and threatening the life of innocent new foals. It is likely that the apparent “contraceptive” effect of PZP is due, in part, to the death of stolen foals on the range, where no one is there to save them.

Foal-Stealing — Hormonal Hypothesis

In the literature, it is noted that foal-stealing is not as common among horses as in some other species.  However, when foal-stealing does occur, Waring (2003) [44] — citing Crowell-Davis and Houpt (1986) [6] — reported that foal-stealing typically correlates with a mare …

Who is close to giving birth or

Who is separated from her own neonate or

Whose foal has recently died.

Sue McDonnell, PhD, a certified applied animal behaviorist and the founding head of the equine behavior program at the University of Pennsylvania’s School of Veterinary Medicine, states:

The explanation proposed (but not known for sure) for this in a mare just before she foals is that her hormones might be a bit misaligned, such that the hormones of bonding prevail a bit earlier than they should and maternal interest and bonding occur prematurely. [21]

However, the kidnapper-mares in question are neither pregnant, nor separated from a neonate, nor grieving the death of a foal.  If the unusual behavior is hormonally-induced, then it would seem that PZP has another endocrine-disrupting effect — and additional unintended consequences — causing social disruption and foal deaths.

Foals May Be Their Dam’s and/or Sire’s Only Offspring

In view of the fact that PZP eventually — if not immediately — causes sterility, any foal could be genetically rare and precious.  In many cases, a foal may be the only offspring of a certain jenny or jack.  By using PZP on the Black Mountain burros en masse, BLM could endanger the herd’s genetic diversity.

Autoimmune Ovarian Disease — Known to Cause Premature Ovarian Failure — Induced by PZP

Tung, Agersborg, Bagavant, Garza, and Wei (2002) found that autoimmune oophoritis (ovarian inflammation) could be induced by injecting test-animals with ZP3 peptide. [36]  The researchers noted that autoimmune ovarian disease is a known cause of human premature ovarian failure.  Here again, is causation of autoimmune disease by a ZP-type product.  Humans and horses are both mammals.  It is logical to conclude that ovarian failure also occurs in horses.  This study confirms other research cited herein.

Included as a reference to the EA?  No.

Autoimmune Oophoritis and Risk of Other Autoimmune Diseases

Varras, Anastasiadis, Panelos, Balassi, Demou, & Akrivis (2013) disclosed that, in humans, autoimmune oophoritis carries the risk of the patient developing other autoimmune diseases. [43]  The correlation between autoimmune oophoritis and subsequent other autoimmune disorders weighs against injecting 165 jennies with PZP.

Prolonged Breeding Season, Unusually-late Parturition Dates with PZP

Nettles’ (1997) previously-mentioned meta-analysis on PZP disclosed additional 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 by Ransom, Hobbs, Bruemmer (2013) of three herds currently being managed by PZP — Little Book Cliffs, McCullough Peaks, and Pryor Mountain — found a prolonged parturition-season — it lasted 341 days. [29]  Ransom et al.’s finding of a nearly year-round birthing season supports the earlier finding by Nettles (1997).  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.

Included as a reference to the EA?  No.

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 described 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 6-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 8 years to recover fertility after just 3 consecutive PZP treatments. [27]

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 80 percent of the herds — including the Black Mountain burros — at levels below minimum-viable population (MVP) per the IUCN, most herds qualify as “small refugia.”

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 or burros 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 et al. (2013) 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.

I note that the Black Mountain EA also omitted the Ransom et al. (2013) study as a reference but did include an earlier study by Ransom, Cade, and Hobbs (2010) on PZP’s influence on issues of lesser importance: Time budgets, social behavior, and body condition.  The 2013 study is certainly more relevant in terms of PZP’s potential impact to the very existence of the Black Mountain burros than was the 2010 report.  The 2013 study’s important scientific findings should inform the decision-making process, but were left out.  Thus, BLM did not use the best-available research.

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. [20]

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. [9]  And as we shall see later in this report, that first shot of PZP may not be their first shot of PZP.

Included as a reference to the EA?  Yes, but the EA said: “However, Knight and Rubenstein (2014) speculated that three consecutive years may trigger infertility in some mares.” (pdf-page 35)

Black Mountain’s EA Lifted Passages Wholesale from Another Fertility-Control EA

When I read the sentence referenced immediately above — that Knight and Rubenstein had “speculated” about PZP triggering infertility in as few as 3 years — it had a déjà vu quality.  I knew I had encountered just that same dismissive-to-science word-choice before.  Indeed I had.  The 2015 Pryor Mountain Wild Horse Range Fertility Control Environmental Assessment DOI-BLM-MT-0010-2015-0006-EA contained that same sentence, word-for-word, on pdf-page 14. [3]  In fact, the entire paragraph that ends in that sentence was lifted directly from the Pryor Mountain EA.  What’s more, most of the paragraph preceding that one was taken directly from the Pryor Mountain EA.  Continuing on, I found example after example of such copying, with minor additions and modifications here and there referencing jacks and jennies instead of stallions and mares.

Questions as to scientific integrity: The fact that the team of 9 BLM-Arizona staffers who prepared the EA copied extensively and word-for-word from another EA suggests that no true analysis was conducted.  I wonder: Did they even read the studies they cited?  Probably not.

More questions as to scientific integrity:  Pdf-page 48 of the Black Mountain EA identifies the BLM National Office staff who reviewed it.  One of the reviewers is the former Wild Horse Specialist for the Pryor Mountain Wild Horse Range, and held that position at the time that the 2015 fertility-control EA was issued.  Did the W. O. Senior Wild Horse and Burro Representative supply his old EA for the convenience of BLM-Arizona staff?  Did he essentially approve his own EA, modified slightly to reference Black Mountain wild burros instead of Pryor Mountain wild horses?

Researchers Again Express Concerns about the Abnormal Life-Spans of Sterilized Mares

Returning to the subject Knight & Rubenstein study, the researchers 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.  The same concern should be taken seriously with regard to jennies, especially in light of their lower fertility and alternating-year breeding cycle.

PZP’s Destructive Antibodies Are Transmitted via the Placenta and Mother’s Milk

It gets worse.  Sacco, Subramanian, Yurewicz (1981) 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. [30]

These findings were disclosed in 1981 — 35 years ago.  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. [19]  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.

Fillies whose dams were injected with PZP while pregnant or nursing will already have PZP antibodies cross-reacted with and bound to their zonae.  Therefore, when those same fillies are injected later, 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.

Likewise, if the Black Mountain jennies were injected while pregnant and / or nursing, their filly-foals would have PZP antibodies inflaming their little ovaries.  Subsequent injections could easily sterilize them in one shot, especially if given prior to puberty.

Included as a reference to the EA?  No.

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. [28]

Imagine if such a catastrophe were to befall the Black Mountain burros, whose herd-immunity would be eroded by PZP.  Note that the Saiga deaths involved antelope-mothers and their calves.  If Black Mountain’s few fertile jennies and their foals perished all of a sudden, that would leave just jacks and sterile old jennies.  The herd would be composed of the living dead, reproductively speaking, its rare alleles extinguished.  BLM would be failing to proactively manage the Black Mountain herd with stochastic events taken into consideration.  That would constitute 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 roundup and remove “excess” wild horses from the range — gathers and 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 3 years, the latest one in 2015.

But evidently every 3 years, in BLM’s mind, wasn’t often-enough.  BLM announced plans to conduct removals every year in the Pryor Mountains despite recently-intensified PZP-treatments.  Friends of Animals, a reknowned animal-advocacy organization that opposes PZP, sued to prevent BLM from initiating the accelerated schedule of gathers.  Friends of Animals prevailed, and the annual removals were blocked.  The Court directed BLM to fulfill its commitments to reevaluate the Pryor Mountain AML. [11 and 15]

As the EA acknowledges, the Black Mountain herd would likely also be subject to annual roundups in order to re-inject the jennies, to re-brand them, and to render veterinary treatment of injection-site abscesses.  What the EA refers to as “opportunistic” field-darting would probably not be adequate to “re-booster” enough of the test-subjects.  Roundups are stressful on burros and costly to taxpayers.  The better and no-cost population-control method is predation by mountain lions, coyotes, and perhaps even reintroduced wolves.


Risks to Humans Who Administer PZP Injections

For BLM and HSUS 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. [38]

However, EPA’s Fact Sheet, the manufacturer’s training, and BLM’s operating procedures fail to inform …

Pregnant women of the reason 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 inform …

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 inform …

All women of the reason why to avoid PZP — due to the risk of ovarian dystrophy, oophoritis, ovarian cysts, depressed estrogen 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 further fail to emphasize the magnitude of the risk — the PZP-in-question is a dose meant for a horse — or, in this case, a burro.

Mandate to Practice Scientific Integrity

Let us return to the Department of the Interior’s (DOI) Code of Scientific and Scholarly Conduct, which 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. [37]

In the EA, BLM has omitted independent scientific findings about PZP’s adverse effects and unintended consequences.  Instead, BLM continues to rely almost exclusively on the manufacturer’s claims regarding PZP’s safety for use on horses or burros and for handling by humans.  BLM and HSUS are thus non-compliant with the Policy and malfeasant in their responsibilities to protect staff, volunteers, and the wild horses and burros.

PZP Manufacturer Violated the DOI Code of Scientific and Scholarly Conduct

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 wild-horse-and-burro advocacy groups that oppose PZP, such as Friends of Animals and Protect Mustangs, and independent researchers whose findings did not fully support his claims.  Indeed, he submitted an Op-ed to The Salt Lake Tribune wherein he accused Friends of Animals and Protect Mustangs of citing “dubious and distorted” data about PZP.  He belittled the research of fellow scientists whose studies on PZP yielded results somewhat different from his own. [19]  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. [24]  The manufacturer also disparaged members of the public — one of whom was appointed to the Pennsylvania Game Commission — that 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.” [18]  By these actions, the manufacturer violated the DOI Code of Scientific and Scholarly Conduct.

PZP Manufacturer Misled Trainees into Believing that PZP Was Safe

BLM and HSUS staff and volunteers receive their training from PZP’s manufacturer in how to handle and administer the pesticide.  BLM and HSUS are 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.

Recall that the manufacturer claimed PZP is “so safe it is boring.” [11]  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-and-burro advocates are lulled into complacency, trusting that PZP is harmless.  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.” [10]  Key words: “no side effects.”  It is disturbing that a person who was, no doubt, motivated by a desire to help the wild horses and burros has been disinformed regarding PZP’s safety-hazards to humans as well as to horses and burros.

PZP — Conclusions about

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.


EA Includes a Reference that Cannot Be Verified and that Perpetrates a Fraud

The APA Publication Manual “contains the complete guidelines on how to cite research in text as well as formatting of material for publication.  It is a set of style rules that codifies the components of scientific writing in order to deliver concise and bias free information to the reader.” [2]

One of the references BLM cited in the EA is listed thusly:

Cothran.  2010.  Personal Communication.  Conversation regarding genetics and related testing.

This citation does not comply with APA standards for a proper scientific reference because a conversation is not “findable” or “retrievable” or “recoverable.” [2]  Thus, the above personal communication cannot be verified.  It should have been mentioned only in text, not in References.  It was also odd that, in the intervening 6 years, a better reference was not secured.

Evidently, the citation was intended in support of the following sentence, found on pdf-page 38.

Extended length between generations provides for lengthening generation time and slows the rate of genetic loss (Cothran, personal communication 2010).

But this sentence, too, had a déjà vu feeling to it.  Sure enough, it was taken directly, word-for-word, from pdf-page 16 of the 2015 Pryor Mountain Fertility Control EA.  In fact, the entire paragraph that contains the above sentence was lifted from the 2015 EA.

What is more troubling is that the reader is led to believe that someone from BLM-Arizona actually had a personal communication with Dr. Cothran back 6 years ago.  Surely, no such conversation happened.  Thus, a fraud is being perpetrated against the reader in violation of scholarly-integrity principles.

Bighorn Sheep — Study Shows No True Competition from Burros

Black Mountain is home to bighorn sheep, prized trophy-targets for hunters.  Extraordinary efforts have been made to translocate sheep into suitable habitat in the state and to augment their numbers.  On pdf-page 25 of the EA, BLM implies that burros compete with bighorn:

Over the very long-term (20 years or longer), if the results of the project are found to be effective in reducing jenny fertility rates (through extrapolation), there could be the potential for a reduction in competition for forage resources between ungulates (desert bighorn sheep, cattle, and burros).

BLM assumes — incorrectly — that burros disadvantage bighorn (and cattle).  That false assumption has been debunked.  Wehausen (1998) concluded that “a negative influence of burros on bighorn sheep demography has not been shown as support for true competition.” [45]  As to the alleged competition with cattle, that false assumption has been debunked too.

Facilitation and Commensalism — Equids Enhance Livestock Production

Some species thought to compete actually facilitate one another’s well-being.  They interact positively and reduce physical stress. [32]  For instance, commensals are animals that eat “at the same table” but without competing.  Such is the case for burros and bovids.  Counter-intuitive but true, research has shown that cattle gain more weight when grazed with donkeys. [25]

BLM neds to stop the range-war, pitting burros against bovids.  Forage-grazing is not a zero-sum game.

Symbiosis — Burros Graze Old Growth — Cattle Prefer New Growth

Wild burros utilize coarse, old-growth forage.  They are like lawn mowers.  They take off the top growth — the dry, unpalatable layer.  This grazing method enables the plants to put down deeper roots, and it prevents weeds from maturing to produce seeds.  Grasses are encouraged by the burros’ frequent “mowing.”  In addition, the fuel-load is reduced, helping to prevent wildfires.

Livestock, in contrast, prefer tender new growth.  They will even return to patches previously grazed — not rested — to get at that new growth. [14]  Thus, by consuming the old growth and making available the new growth, wild burros make conditions better for the range and better for livestock.  Arizona needs more burros, not fewer.


Scarlet Letters

BLM procedures would call for the 165 jennies treated with PZP to be freeze-marked with three letters on both sides of their hips — left and right.  Each of the letters would be 3½-4 inches in size.  The purpose of these huge brands is to make it easy for HSUS researchers to spot and dart the jennies from a distance.

First, please note that the Act prohibits the branding of wild horses and burros.  The Act provides no exemption for BLM or HSUS.  The disfigurement of burros is unacceptable.  Surely, no jennies uglified with such blemishes would ever be adopted.  Their marred appearance would also spoil the wilderness experience of eco-tourists who come to see the lovely burros in their natural habitat.  Like Hester Prynne, the Black Mountain jennies would wear their prominent “scarlet letters” to announce their shameful status for the rest of their life, their only “sin” being their fertility, for which they would be punished.

With regard to tracking and locating wild horses, BLM should employ inconspicuous electronic devices, such as tracking tags.  The use of disfiguring freeze-marks must be prohibited.  It should be noted that electronic tracking can also provide a record of each burro’s personal data for longitudinal studies.  It is time for BLM to use modern methods instead of destroying the jennies’ beauty.

Recreation and Wild Burro Viewing

As it is, most wildlife-tour visitors have to search long and hard to find any wild burros to view in the Black Mountain HMA.  So, with 165 of the jennies injected with PZP, there would be fewer families, and especially, fewer darling “babies” frolicking on the range.  The presence of foals delights recreational visitors; the absence of foals disappoints them.  Forelorn, childless jennies disfigured with huge freeze brands on their rumps would be repulsive, and not what the public wants to see.  Esthetics count, and recreation is fast-becoming the predominant use of our public lands.  Please don’t ruin it for us.


Marybeth Devlin

Protect Mustangs is an organization who protects and preserves native and wild horses.


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Protect Mustangs is an organization who protects and preserves native and wild horses.