PZP, the elephant in the room

“If you had a patient with a severed artery would you tourniquet the limb before addressing internal injuries? Or would you let the patient bleed out while you argue if you need x rays or a CT scan? PZP is a tourniquet to stop the bleed of wild horses leaving the range while we address other issues. Plain and simple.”

A proposal given in August of this year by Jeanne Nations of the NE Nevada Resource Advisory Council (RAC) and Laura Leigh of Wild Horse Education was barely noticed. However in October, right before the major “giving season” for non profits, an expanded proposal was given to the RAC and members of the Bureau of Land Management (BLM) by Nations, Leigh, Neda DeMayo and Dr, Jay Kirkpatrick (practices proposed endorsed by Return to Freedom, Animal Welfare Institute, The Cloud Foundation, Wild Horse Education and many more). That proposal quickly became the focus of a “bash campaign” by a small handful of competitive non profits and one of the BLMs roundup contractors (In a year that the contract is being modified to include humane care and access and roundups are at the lowest level since 1977). (you can read about the October meeting here: https://wildhorseeducation.org/2014/10/23/rac-ctr-wwww/ )

Although being used successfully in many areas like Assateague managed by the fire department (that became a joke, “How do you manage a wild horse population? You make the federal government and a local fire department switch places… but then our houses would all burn down). And is being used, minimally by the BLM, in places like McCollough Peaks that was the subject of this article in April that went completely without a “bash fest” in social media http://www.slate.com/articles/health_and_science/science/2014/04/wild_horse_population_crisis_birth_control_with_pzp_or_roundups_by_the_blm.html It is being used in multiple areas by lesser known sanctuaries as well like Sky Mountain in a cooperative with Forest Service at the Carson National Forest. (It has also been used on deer for decades and on elephants in African sanctuaries).

For years the advocate community has sent letters and commented that the BLM is addicted to roundups. That they (BLM) fails to address the program from anything but a “remove and warehouse” mindset with nearly ten thousand wild horses a year losing their freedom from 2009-2012, over 5000 in 2008, over 8000 in 2007… I think you get the picture. One of the admonishments was that BLM failed to use PZP appropriately (times of year) and in less than 3% of the wild population. In June of 2013 the National Academy of Sciences (NAS) in a million dollar study, admonished the BLM for failure to use birth control and a lack of data program wide.

So why all the huh bub this time? Maybe it was the unfortunate time of year of the proposal? Maybe it goes into a “personality” conflict? Or maybe it is that it might just work?

The proposal given in October was primarily focused on a small portion of the Antelope Complex on the eastern border of Nevada and pilot programs beginning in two other districts. The presentation itself was given by (or endorsed by) members of nationally known wild horse advocacy groups.

The use of a form of PZP (native) has multiple practical purposes for implementation. It slows population growth and allows data collection from herd structure, genetic map, migratory patterns (that include boundary issues), forage utilization. It adds the ability to create and track these aspects of the herd in a “trend map” to address the planning process from a scientific basis. Isn’t that what is lacking in the program? Wont that allow things like genetic bankruptcy to be addressed and any flaws like numbers of horses on the range to be modified?

What is PZP? (taken from the PNC project for wildlife contraception)

A non-cellular membrane known as the zona pellucida (ZP) surrounds all mammalian eggs. The ZP consists of several glycoproteins (proteins with some carbohydrate attached), one of which, ZP3, is thought to be the sperm receptor (the molecule which permits attachment of the sperm to the egg during the process of fertilization). The PZP vaccine is derived from pig eggs. When this vaccine is injected into the muscle of the target female animal, it stimulates her immune system to produce antibodies against the vaccine. These antibodies also attach to the sperm receptors on the ZP of her own eggs and distort their shape, thereby blocking fertilization (see Paterson and Aitkin 1990).

Thus far PZP has been a promising form of contraception in wildlife because

1. it has prevented pregnancy an average of 90% of the time in treated animals
2. it can be delivered remotely by small darts
3. the contraceptive effects are reversible
4. it is effective across many species
5. there are no debilitating health side-effects even after long-term use
6. it has almost no effects on social behaviors
7. the vaccine cannot pass through the food chain
8. it is safe to give to pregnant animals (see Kirkpatrick et al. 1996b).

So why are these points being either misrepresented or ignored?

It may be the use of terminology used in research and implementation documents. We will try to explain some of the terms and why.

“Overpopulation.” This seems to be the most recent “buzz word.” There are accusations that if you support PZP you agree to “overpopulation.” This is a spin worthy of Maytag. The term overpopulation (in discussions on BLM land) arrives from another term “Appropriate Management Level” or AML. This is the number of animals BLM says the land can sustain. The levels are set in a land use planning process (for decades not engaged by the advocacy community). The term creates a legal definition, not a justified one. If we go back to what WHE has been saying (as an example in court documents on Owyhee) is that AML is not based on any scientific equation. The NAS concurred in their report that also admonished BLM for not using birth control. Litigation is pending in two states that centers around AML from the livestock interests wanting horses off the land in Utah and in Nevada under the Nevada Association of Counties (NACO). In the NACO action we are Intervenors and point out that there is no data to support AML and the no data to support the over allocation of forage to private livestock interest.

So where in this mix do we support an assertion of “overpopulation?” The implementation of native PZP will allow the opportunity to gage population levels in a scientific fashion. (We use the term “overcrowded” by too much given to other interests and explain that distinction here: https://wildhorseeducation.org/2014/11/10/overcrowded-vs-overpopulated/)

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

Soil and water contamination. PZP is a protein that breaks down. It has been used for decades in deer, wild horses, elephants etc. We do not have birds and fish and squirrels dying in Assateague from PZP use or lions or coyotes from the use on deer and elephants. Scientifically this is purely not the truth.

“Feral.” This is another term that can make a wild horse advocate see red. But the use of PZP does not change the legal definition of a horse. A horse (or burro) is legally designated by where it stands on the land. A horse on state land or Fish and Wildlife is legally designated as “feral.” A horse on BLM land has the legal definition of “wild.” Treating a mare at McCullogh Peaks does not change her status to feral under law. So if you read the word in research documents please understand why before reacting to it.

“Behavior Changes.” All kinds of behaviors are being attributed to PZP use from gang rape to foal murder. At Assateague we do not see tourists running screaming after watching the horses, we see them taking their children and the community getting a great reputation. In wild, untreated populations, stallions have been documented killing foals (although rare) and mares are mounted by more than one stallion (again rare, but documented). PZP also wears off and any stressor associated with any lack of fertile mares could be relieved in contrast to surgical techniques like those used at Sheldon National Wildlife Refuge (we documented how vasectomies keep males thinking they are fertile and a lack of fertile females due to hysterectomies create an intensity in behavior we, personally, have witnessed nowhere else).

Harder to Catch and will make “gathers” more difficult. This assertion has no basis in any factual information as no widespread use of PZP has been implemented. And if PZP native is successful? Helicopter removals would be increasingly diminished in any area treated.

Assertions in the “bash the concept game” even include those that claim payoffs by BLM to those making the proposal. BLM has never used PZP as an appropriate tool. At each turn there are obstacles in gaining understanding of the benefits of implementation and data collection. If we were into a “spin machine” of our own we could assert payoffs to those opposing the programs by BLM (because they are addicted to roundups), the contractor (because a horse not born is one they can not be paid to remove), the livestock industry (that wants no data collected so they can continue to use the horse as a scapegoat), but that is not what we do.

We are on the ground continuing to monitor multiple herds, animals in holding, fight for humane care and access and are addressing issues in land use planning to protect our wild horses and burros and keep them free on the range.

This post is made by request by several people asking us to. Addressing this has taken time from our work and away from the multiple threats facing our wild ones that we are in the field addressing.

We ask that YOU keep in mind the “big picture” of 50,000 wild horses in holding facilities, proposals to surgically sterilize wild horses, legal actions against horses by the livestock industry, changing public land policy, sage grouse, etc, etc. Then we ask that you put PZP in perspective as one of the tools that can be utilized to satisfy legal requirements and gather real data that can then be used to create sound management plans.

If you look at the work of WHE… all of our work… are we spending the vast majority of our time on PZP? Or are we working very hard on multiple levels to actively engage to protect wild horses and burros from abuse, slaughter and extinction?