Rebuttal of Misinformation Posted by Pro-PZP Entities
Issue # 1. Criticism of devoted scientists and advocates

Discussion: Sometimes the truth hurts, and sometimes the only way to wake misguided people out of their imaginations is to speak in the strongest of terms.
Issue # 2. Self-regulating herds.

Discussion: The pro-PZP groups parrot the BLM line that there is an insufficient number of large predators to effectively control wild horse populations. But what happened to the predators? They have been virtually exterminated due to excessive hunting by sportsmen and excessive culling by Wildlife Services, which kills on behalf of public lands ranchers. Instead of joining with conservation organizations and animal protection groups that are fighting for the predators, the PZP adherents want us to accept defeat. We won’t. We believe in a thriving natural ecological balance, which must include predators, large and small.
Issue # 3. Impact on genetics and social structure.

Discussion: The pro-PZP groups say it is too late, that the herds have already been genetically and socially disrupted by decades of roundups, removals, and relocations. Their solution? PZP. Thus, we are essentially being told that underpopulated herds suffering from genetic decline should have their numbers further reduced and their mares eventually rendered sterile. We say, “Absolutely not.” The answer is to fight for the herds, for viable populations, for genetic diversity, for normal behavior, for natural fertility.
Issue # 4. Economics.

Discussion: Pro-PZP groups want us to accept BLM’s mismanagement as a fact and learn to live with it. They say we should let wild fillies and mares be slowly sterilized. Using PZP will, “over time” reduce removals, they claim. If only that were so. A review of BLM’s population estimates for herds scheduled for gathers this year showed case after case of dizzingly inflated numbers, even for years in which PZP would have been at maximum effect. BLM is not a trusted partner! BLM is using PZP to accelerate the demise of the herds, combining slow sterilization with massive removals on any pretext. The pro-PZP groups are unwittingly playing into BLM’s nefarious schemes to wipe out the wild horses and burros.
Issue # 5. Whether PZP is a pesticide.

Discussion: The EPA classifies PZP as a pesticide for use on non-food animal pests. It exerts a contraceptive effect by inflamming the ovaries, causing ovarian dystrophy, destroying oocytes in growing follicles, and depleting resting follicles. The EPA warns that PZP is a biohazard are advises women that accidental injection could cause infertility. The EPA cautions pregnant women to avoid handling PZP, despite PZP’s supposed non-interference with a pregnancy in progress. Thus, the possibility is raised of harm to an unborn child by exposure to PZP in the womb.
Anne-Marie Pinter” The crux of this is; multiple attacks on the immune system; stress then a stimulant…..then you have the makings of “Autoimmune disease” as it is termed in today scientific world; “Autoimmune diseases are due to an overacting immune system, that starts attacking their own body”
Issue # 6. Whether PZP-22 is the best answer, if fertility control is to be used.

Discussion: No. PZP-22 has the same adverse-effects profile, except it is longer acting. Once “native” PZP opened the door to artificial population control, BLM looked for ways to make it last longer so they would have less work to do. Thus, one-year PZP is often rejected as “not feasible” and “not practical”. For the most part, BLM wants to keep holding helicopter roundups on a rotating basis every four years, as they’ve been doing. In BLM’s ideal world, they would continue conducting helicopter gathers to catch and corral the mares, shoot them up with “PZP-48”, remove most of the herd anyway based on exaggerated population estimates, and then retire to their offices to sit back for another four years.
Issue # 7. Whether “native” PZP is a sterilant.

Discussion: Ultimately, yes. But if a filly or mare has a strong immune system, even the first immuno-vaccination could provoke such a powerful immune response that she would immediately be rendered permanently sterile. With multiple consecutive injections, sterility is pretty much a certainty. Exceptions would be mares with a weak or depressed immune system, which would not respond to the PZP. That’s why some mares get pregnant in spite of PZP, and why PZP inadvertently selects for immumo-compromised horses. Over time, herd health would suffer and the population could be wiped out by an inability to fight off disease.
Issue # 8. Whether PZP is a chemical contraceptive and whether it poses a significant risk to inoculated mares and their foals.

Discussion: PZP is a chemical, classified by the EPA as a pesticide, approved for use against “feral” horses deemed to be pests. Let it be understood that our wild horses are Federal, not feral. PZP works to provoke an immune response that has been shown to target the ovaries, causing inflammation and dystrophy. PZP destroys oocytes in growing follicles and depletion of resting follicles. So, yes, it does pose a significant risk to mares injected with such a powerful and destructive “vaccine.” Because pregnant women are strictly warned against handling PZP, even though PZP is said not to interfere with a pregnancy already in existence, the possibility of ovarian or testicular degeneration in the developing embryo or fetus is of concern. Therefore, a pregnant mare’s unborn foal could potentially be affected. The cautionary principle would call for rejection, not injection, of such a substance.
http://www.publish.csiro.au/?paper=R96054
Issue # 9. Whether PZP causes ovarian damage and other pathologies.

Discussion: Yes, it does. The pro-PZP groups endeavor to differentiate “native” PZP from other PZP formulations and claim that “native” PZP works completely differently from the rest of the PZPs and ZPs. Not so. Recent studies have disproven the theory that ZPs block fertilization. Instead, ZP vaccines cause ovarian dystrophy, oophoritis (inflammation of the ovaries), destruction of oocytes in all growing follicles, and depletion of resting follicles. That is why, regardless of PZP type, it takes years for fertility to be restored (if ever) and why eventual sterilization occurs with certainty after multiple inoculations. Kirkpatrick, Liu, Turner, et al. (1992) found that ” … three consecutive years of PZP treatment may interfere with normal ovarian function as shown by markedly depressed oestrogen secretion.”

http://www.pubfacts.com/detail/1317449/Long-term-effects-of-porcine-zonae-pellucidae-immunocontraception-on-ovarian-function-in-feral-horse

Certainly ovarian damage should have been suspected 23 years ago and investigated, in light of “markedly depressed oestrogen secretion” in PZP-treated mares. Yet despite the developer’s own finding in 1992 that PZP appeared to “interfere with normal ovarian function,” the product was promoted as a safe vaccine that merely blocked fertilization. Recent independent studies, based on examining the reproductive organs of sacrificed experimental animals [note: whether they were “sacrificed” to determine the organ-damage has to be verified], revealed the ovarian destruction, clearly disproving the previous assumption.
Issue # 10. Whether PZP is paving the way for use in humans.

Discussion: No, it’s not. Interesting choice of argument that PZP’s 95 percent efficacy rate would be too low for human contraception. Compare PZP’s rate with that of birth control pills, which are only 91 percent effective unless perfect compliance is achieved, no conflicting medications are taken, and no conflicting health issues are present. And compare PZP’s efficacy rate to that of condoms. With typical use, 85 percent of women relying on prophylactics worn by their partners successfully prevent pregnancy. Interesting choice of argument also in comparing PZP to the influenza vaccine, whose efficacy is reportedly in the 10-60 percent range.

http://www.webmd.com/cold-and-flu/news/20150115/flu-vaccine-effectiveness
Issue #11: Whether 150 is the lowest viable population of a wild horse herd to be genetically healthy.

Discussion: The International Union for Conservation of Nature has determined that 2,500 is the minimun viable population for a wild horse herd. A recent meta-analysis suggested that number should be doubled. Interestingly, the Pryor Mountain herd, which the pro-PZP groups cited, is in genetic decline, according to the most recent report from Dr. Cothran. His recommendation? Increase the size of the herd.
Issue #12: Whether or not the NAS recommended fertility control in Federal wild horse herds.

Discussion: The NAS researchers were prohibited by BLM from collecting their own data. They were required to base their recommendations on BLM’s wild horse population estimates, which are exaggerated by more than double. So, it was to be expected that NAS would recommend fertility control. What else could they be expected to do?

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The Example of Assateague Island National Seashore
Examining PZP through the eyes of the Assateague horses themselves:

Horses have not been handled.

Reply: Right. They are shot with a dart gun, so human hands do not touch them, although the PZP causes their ovaries to become inflamed.

Mortality rates have declined significantly, especially among foals.

Reply: Nature operates by survival of the fittest, which means those that are not fit, perish. Reduced mortality may not correlate with a herd being self-sustaining because most of the herd is not reproducing.

Body condition scores have improved.

Reply: Mares in good or improving body condition have a hugely increased tendency to produce colts. This could lead to a gender imbalance. Having too many colts negatively impacts the genetic diversity of a herd.

Longevity has increased dramatically, with mares living three times longer than pre-PZP.

Reply: Longevity, combined with sterility, reduces a herd’s viability in both the short-term and the long-term. Here’s the analogy. On average, American women live about 75 years. If PZP caused them to live three times longer, for 225 years, would that be a good thing if none were allowed to have more than one child?
Discussion: Let’s take a look at another East Coast wild horse herd being managed on “native” PZP: Corolla. The low population limits imposed on that herd have led to birth defects. To increase gene pool diversity, a stallion from the Curritick herd, 150 miles south of Corolla, was translocated. However, he may never win a band and, besides, the mares are contracepted, which makes his job more difficult.

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Issue #13: Whether PZP inoculations can introduce pathogens, and whether administering PZP will cause laminitis, resulting in horses’ hooves to fall apart.

Discussion: This is a two-part issue. As for the first part, yes, it is possible for any inoculation, including PZP, to introduce pathogens. However, the second part appears to be a straw man story invented by pro-PZP parties and falsely attributed to PZP’s critics.
Issue #14: Whether PZP-mares stay in perpetual estrus, causing unrest in the herd.

Discussion: The incorrect word above is “perpetual.” Studies have found that mares on PZP have more estrus events and cycle beyond the normal breeding season. Mares in estrus give off pheromones [note: verify this], which are attractants for stallions. With more estrus events occurring in his mares, the band stallion will likely experience more challenges to his leadership. Yes, foals can get hurt when stallions do battle. A recent study by Ransom et al. showed that herds managed by PZP have a breeding season of 341 days. So, by “perpetual” we mean nearly year-round: 365 days minus 24 days.
Issue #15: Whether pharmaceutical companies are involved with the Assateague Herd project and other native PZP projects.

Discussion: This appears to be a straw man accusation. Pharmaceutical companies have no interest in PZP in any of its various iterations because of the long time it takes to restore fertility (four to eight years), the risk of irreversible sterility, and as has been pointed out, the prospect of settling bad-drug lawsuits.
Issue #16: Predation is the only viable ecological solution.

Discussion: To have a thriving, natural ecological balance (TNEB), an ecosystem must have predators.
Issue #17: The allegation that anti-PZP groups claim PZP, specifically “native” PZP, is patented.

Response: This appears to be another straw man accusation. ZonaStat-H is a proprietary product registered with the EPA by the Humane Society of the United States. It is possible that some persons confused “proprietary” with “patented.” Merck originally held the patent but let it lapse due to the adverse effects listed herein.
Issue #18: Some organizations appear to support perpetuating the problem or creating a new problem.

Response: If your income or your funding depends on there being a problem, you will do things that keep that problem going or create new problems to take its place. Once PZP has sterilized one herd after another, and once BLM zeroes out such HMAs, then these groups will surely take up a new rallying cry: Recreate the herds! They’ll say that no one knows why the herds are dying out (yes, you do; it was the PZP), but let’s sign petitions to bring in substitute horses to reinvent such and such herds. Of course the original herd and its unique genetics will be lost forever, but now these groups will have a new life with a new cause.
Issue #19: BLM is not managing wild horse HMAs according to the Law.

Response: The clear intent of the Act was that mustangs would benefit from the principal use of their dedicated range and its resources. Yet, within 98 percent of their legally designated habitats, wild horses and burros are relegated to a minority share of the forage.
Issue #20: Wild horse sanctuaries are pale imitations of real wild horse herds.

Response: The Law provides for eco-sanctuaries. They are called HMAs. The need for private sanctuaries is due to BLM’s mismanagement, to inadequate AMLs, to removals in numbers that deluge the adoption market.

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© Protect Mustangs, May 17, 2015