Wild horses have potential to stem killer toxins on American rangelands

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Most Americans have heard of ebola, anthrax and the Spanish flu, all of which are deadly pathogens and all of which have killed millions of people over the decades.

However, there are some diseases caused by toxins that are not so well-known, yet have capacity to sicken and kill both people and animals in great numbers.

Prions are such a toxin and pose a serious health risk to humans, cervids (deer, elk and moose) and also to livestock, where in cattle, prions manifest as ‘mad-cow’ disease (BSE).

It seems we are currently faced with a new and emerging challenge to our North American deer, elk and moose herds, locally and nationally from such a prion-based disease.

The prion infections in deer, elk and moose (‘cervids’ collectively) is causing Chronic Wasting Disease (‘CWD’); a very serious illness that can kill. And recent experiments with monkeys suggests it may be communicable to humans.

And it may only be a matter of time before it starts moving from cervids and their grazing environments into our livestock, if livestock are commingled with cervids grazing upon infected grasses and brush (suspected prion vectors).

In fact, one of the leading scientific investigators into prion infections wants to start burning grasses to eliminate suspected grass-borne vectors of CWD, according to this N.Y. Times article.

In addition to adversely affecting the $10-billion dollar annual hunting industry in America, CWD and infectious prion diseases certainly have the potential to be devastating to the livestock industry.

Prions are the infectious agent in ‘mad-cow’ disease in cattle, and ‘scrapies’ in sheep.

Prions are misshapen proteins and are particularly worrisome compared to bacteria and viruses because they can be transmitted into animals from contaminated grasses and brush by ingestion, as well as potentially transmitted between animals via contact through other environmental vectors. In the environment, prions can remain infectious for very long periods of time compared to some bacteria and viruses.

The fact that we currently have very little surveillance data (in most geographical areas none!) as to the scope and level of infection already present in America and its cervid herds, makes the problem quite serious.

Dr Mark Zabel
Dr Mark Zabel

In fact, according to Colorado State University’s Dr. Mark Zabel, who was kind enough to spend a couple hours on the phone with me over the past week, there is very little data on which locations across America may be CWD enzoonitc areas.

We really have no idea as to what extent CWD is present in local and west coast cervids and in the grazing environments in and around our forests. And there are already deer and elk that arguably show symptoms of CWD around the western states.

As I have learned from Dr. Zabel, the symptoms of prion disease can easily be mistaken for other causes, such as selenium deficiency. And given the complexity of the diagnoses and limited laboratory facilities able to make such diagnoses, prion diseases can be easily overlooked, allowing it to potentially extend into other animal populations.

According to a Scientific American article, misdiagnoses of prion-involved disease in humans may be more widespread than believed:

“In the human form of mad cow disease, called Creutzfeldt-Jakob, a person’s brain deteriorates — literally developing holes that cause rapidly progressing dementia. The condition is fatal within one year in 90 percent of cases. The culprits behind the disease are prions — misfolded proteins that can induce normal proteins around them to also misfold and accumulate. Scientists have known that these self-propagating, pathological proteins cause some rare brain disorders, such as kuru in Papua New Guinea. But growing evidence suggests that prions are at play in many, if not all, neurodegenerative disorders, including Alzheimer’s, Huntington’s and Parkinson’s, also marked by aggregations of malformed proteins.”

Recently, an article published in USA Today’s Wisconsin Farmer discussed another concerning study about prions and CWD:

“Three of five macaques that were fed infected white-tailed deer meat over a three-year period tested positive for CWD.

“The meat fed to the macaques represented the human equivalent of eating a seven-ounce steak per month.”

It is quite important to note that among large North American herbivores, wild horses (an American native species: click here) are uniquely immune to prions, arguably so through some evolutionary process, which we do not yet understand.

And by abating grasses and brush (each horse consuming 30lbs. of dry grass and brush daily) one of the suspected vectors, wild horses can meaningfully reduce environmental prions affecting other grazing animals, including cervids. This is important because the rate of infection for this prion disease (CWD) is believe to be dose-related. Such grazing by wild horses also has the added benefit of reducing the fuels (grass and brush) for catastrophic wildfires as I discuss in this article.

As we consider all of the foregoing, in light of the BLM’s notion of removing even more wild horses from public lands to increase and extend grazing areas for cattle and sheep into known grazing areas where cervids are present, such a move is clearly a “bad idea” according to Dr. Zabel.

Grazing livestock in proximity to cervids may subject cattle and sheep to prion infections, which may initially be very difficult to perceive or diagnose short of a laboratory analyses, and potentially thereafter, infecting humans who have ingested the meat of any infected animals.

However, I defer to Dr. Mark Zabel, one of the world’s leading experts on the subject, who addressed that concern in the message below where I posit the question to about co-mingling cattle and sheep in areas grazed by cervids:

—–Original Message—–

From: Capt. William E. Simpson – USMM
To: Zabel, Mark
Sent: Thu, Jul 12, 2017 21:16

I think we should have a discussion about how involved you and/or your team would like to be in studying a deployment of wild horses into an ecosystem alongside cervids. And if so, it may be important to survey the existing animals in the area(s) before the horses are deployed in developing some baseline data.

You’re the expert so you’ll have to tell me, but it seems logical that there may be some vector/biological path from the prions causing CWD in cervids to potentially infect livestock via some form of transmission, possibly from cattle and sheep being on grazing lands and sharing water sources with infected cervids? The cattle industry cannot afford any further BSE or similar out breaks (one sick cow with ‘mad-cow shuts the industry down), and they are pushing the US Forest Service hard to graze more cattle in immediate proximity to cervids, sharing grazing and water sources. I think that may be unwise until completed surveys have been conducted and pathways for transmission have been fully explored.

From my relatively ignorant perspective on potential transmission paths, it seems reasonable to think that the cattle/sheep industry would;

1. Want to avoid grazing cattle and sheep in close proximity to cervids, at least or until cervid populations could be surveyed for prions and rates of infection; and,

2. Begin the study of equids and cervids co-existing in an ecosystem to determine what aspect of the evolutionary mutualism has and may continue to benefit cervids through equid mutualism, and possibly determine what mechanism led to the horse’s acquired an immunity to the prions … and if there is a potential cure that can be applied; gene therapy …  epigenetic path to resistance?

The USFS, BLM and the Cattle industry might be inclined to help fund such surveys and studies for the obvious reasons …

From: Zabel, Mark 
To: Capt. William E. Simpson – USMM
Sent: Thu, Jul 13, 2017 11:48 am

You are absolutely right and I would strongly discourage any cattle from grazing in CWD endemic areas. Really short-sighted and bad idea until we know further how prions jump species barriers. Cattle ranchers would not like the bad publicity if the media and beef consumers found out that cattle are mingling with cervids, especially in confirmed CWD enzoonitc areas.

Majestic, one of the wild stallions of Wildhorse Ranch.

Now that there are fewer than 50,000 wild horses ranging-free in America and with Sec. Zinke looking at killing the balance of all the remaining wild horses at the BLM corrals (about 40,000), we seem to be facing a very serious time-sensitive issue where the BLM (Sec. Zinke) is considering slaughtering (soon) the only known cost-effective solution to a potential problem with a national scope; this emerging prion problem.

So what happens if Secretary Zinke allows slaughter of the only animals (wild horses) which can effectively abate the prion vectors in the wilderness and forest lands of the BLM and USFS? Who knows? But on its face, I think it has disaster written all-over it. It reminds me of a forester who told me that ‘BLM’ stands for Bureau of Large Mistakes.

Killing the only potential natural and readily available solution to a couple of very serious emerging problems seems like the ‘bad idea’ of all time to me!

Let’s examine the benefits of harnessing the natural abilities of wild horses to once again serve mankind by using them instead of killing them:

  1. BLM saves about $50m/annually in costs related to keeping the 40,000 horses corralled; and,
  2. Mitigated wildfire fuels saves insurance industry hundreds of millions annually in losses as a small fraction of their current multi-billion dollar losses; and,
  3. Less fire means less fire suppression costs to the USFS (USFS spends 1/2 of its budget on fires), and savings to USFS and BLM-DOI translates to taxpayer savings; and,
  4. Grass and brush abatement by wild horses (immune to prions) may alter prion disease vectors (grasses and brush) and introduction into game animals (deer, elk, moose) that are now succumbing to the prion-caused chronic wasting disease (CWD), which is good for hunting lobbies ($10b annually). Having the immune wild horses abate excess grasses and brush may also provide some fire-walling against transmission of emerging prion diseases into domestic livestock herds from deer and elk (mad-cow – livestock lobby) and potentially infecting humans (medical community). Releasing wild horses back into the wilderness and creating a pilot program to study their affect on CWD may lead to some insights and methodologies for protecting livestock; and,
  5. Last but not least, Wild Horses and Burros provide highly beneficial symbiotic mutualisms to all of their historical ecosystems and add to the aesthetics and tradition of the American wilderness. This final statement is consistent with the Congressional preamble to the 1971 Wild Burro and Horse Protection Act. 
Wild horses in the Pryor Mountains.
Wild horses in the Pryor Mountains. © Jana Wilson/BLM


(PUBLIC LAW 92-195)  §1331. Congressional findings and declaration of policy

“Congress finds and declares that wild free-roaming horses and burros are living symbols of the  historic and pioneer spirit of the West; that they contribute to the diversity of life forms within the Nation and enrich the lives of the American people; and that these horses and burros are fast disappearing from the American scene. It is the policy of Congress that wild free-roaming horses and burros shall be protected from capture, branding, harassment, or death; and to accomplish this they are to be considered in the area where presently found, as an integral part of the natural system of the public lands.”

Concerned readers should write, email and call their local representatives, state representative and especially DOI Sec. Zinke and AG Sec. Sonny Purdue, and weigh in on the pending decision to slaughter the relatively few remaining wild horses.

Horses have served mankind over the millennia and are a gift from our Creator.

God’s law, which is above man’s law, and which is codified in the Bible clearly states that eating horses is forbidden, according to Leviticus-11 and Deuteronomy-14.

Eating horses or burros is also forbidden under all other Mosaic Law.

Is it too much to ask that our own government and its agencies do what’s right for everyone for a change?


William E. Simpson

William Simpson is the author of Dark Stallions - Legend of the Centaurians, proceeds from which go towards supporting wild and domestic horse rescue and sanctuary. » Read Bill's profile

6 thoughts on “Wild horses have potential to stem killer toxins on American rangelands

  • July 16, 2017 at 12:02 pm

    Leave our horses free and alone. We will fight for our horses.

  • July 20, 2017 at 7:41 am

    Thank you again for a very well written case for the necessary existence of our equine roaming free on their native land. I would be suspicious of the intent of the cattle industry. When they feel a threat to their bottom line they could call for free the wildlife services contractor and have the deer, elk, etc exterminated without any testing. Which they have done in the past. If publicized some excuse in talking points to placate the public will than be sent out. Sorry, for my attitude – please keep up your articles and well thoughtful study. Thank you again Mary

  • July 22, 2017 at 5:44 am

    Bovine Spongiform Encephalopathy has resulted from ranchers grinding up dead cattle and feeding their remains to live ones. If a human being eats beef, he is in danger of developing it, too; the prions can not be cooked out of it. Let the horses run free and eat their native foods while they nourish the soil with their uncontaminated droppings. Horses don’t eat meat.

  • August 28, 2017 at 8:37 am

    We have 5 days left before Congress come back and make a ruling on the Wild Mustang , to kill them by shooting them or send them all to Slaughter . It is up to all of Us to be a POWERFUL VOICE For the Wild Mustangs , They Have a Right to Live on their range Wild and Free. Please Call your Senator and tell them that you are against this proposal that the Senate is going to Rule On .. THe Wild Mustang Need our Help our Voice to Speak for Them . I Opposed Slaughter and the removal of the Wild Mustang and Burros from the RANGE > they have rights to Roam Free on the lands they were born on. Wild Freedom Federation

  • October 19, 2017 at 3:51 pm

    Please site the studies used to determine any immunity wild horses have to prions. And also, how many horses it would take to eat affected forage or enough of it to erradicate this disease? It seems to me that having made a jump to monkeys, leading to a likelihood of manifesting itself as other disease diagnosis in humans, it would make sense that we may very well see it in horses over time. There has not, to my knowledge, been any studies proving wild horse immunity. I really don’t want them unnecessarily exposed, or experimented on to find out.

  • October 23, 2017 at 5:15 pm

    Here’s a thought: Stop eating meat. It’s healthier for people, and it’s better for the environment. No overgrazing by livestock means more forage for wild horses. No horses in government holding, no tax subsidies for ranchers, no tax dollars to eradicate predators or round up up horses, means massive savings of our tax dollars, and healthier ranges. What a concept!


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