Genetically Modified Deer Won’t Stop CWD. Here Are 7 Reasons Why.

May 21, 2024 By: NDA Staff

You may have heard some people claim we can fight chronic wasting disease (CWD) through breeding and releasing genetically modified, CWD “resistant” deer. NDA believes every potential solution to the CWD problem should be considered and studied carefully, including genetic solutions. However, captive deer breeders are rushing to demand government funding to breed and sell genetically modified deer to private landowners for release into the wild. Oklahoma politicians recently passed a bill into law to help do just that. 

NDA, other conservation groups, professional wildlife biologists, and wildlife disease experts are alarmed by this hasty action. Here is a summary of the concerns and why we support more research to find actual evidence this technique can work – and not cause more problems than it solves – before it is rushed into deployment.

More Infection, Not Less

Deer with a gene known as “96S” have been found to survive slightly longer than other deer when infected with CWD. Though often referred to as “resistant” deer, they are not not immune to CWD and will still die from infection. These deer are still carrying and spreading a contagious disease. Since CWD-positive deer can infect other deer, longer survival may actually increase spread of the disease to other deer.

96S Deer Have Other Undesirable Traits

The 96S gene is a recessive gene that is very rare in the wild, probably for a good reason. Deer with this genotype are less fit for survival in free-ranging deer herds. Mother Nature weeds them out very quickly. Breeding captive deer for this trait may make sense because animal husbandry techniques can keep those animals alive, but wild deer are not afforded the same luxuries. 

A Risky Diversion of Research Funding

Captive deer breeders are seeking government funding to breed so-called CWD-resistant deer when the science behind the claim is unproven. Most biologists are highly skeptical. Because Oklahoma recently passed legislation to fund captive breeding, deer breeders in more states will likely try to secure funds as well. This could potentially divert funds away from other more important scientific research and CWD management efforts and invest them in an unproven, unlikely, theoretical hope. 

Liberated Deer Could Introduce CWD

The Oklahoma plan allows for captive-bred deer to be released into the wild. There is no foolproof live-deer test for CWD, which is why many captive deer facilities continue finding CWD in their herds and unknowingly moving it to new facilities. So, released deer could very well be carrying the disease themselves and spreading it to wild deer upon their release. To fight the ongoing spread of CWD, we need to stop the movement of live deer and elk – period. Even more important is to prevent the escape of captive deer into the wild. Actively releasing captive deer is an extremely bad idea.

Because there is not yet a completely reliable live-deer test for CWD, we cannot be certain any captive-bred deer or captive herd is CWD-free. Transporting and releasing captive deer could move CWD into new areas.

Liberated Deer Won’t Change Wild Deer Genetics Anyway

Numerous scientific studies have shown we cannot manage genetics of wild deer through selective hunter harvest or through releasing small numbers of deer into large wild populations. Releasing captive-bred 96S deer into the wild would not reduce CWD in a deer population, and it would not change the genetic makeup of Oklahoma’s – or any other state’s – wild deer herd.

Resistance is Likely Only Temporary

Already new strains of CWD have appeared, and more can be expected in the future. Today’s “resistant” deer will likely encounter new strains of disease that circumvent their resistance. Worse, there is evidence that certain genetic traits in some deer cause them to give rise to new strains of CWD that are more infectious even to 96S deer.

The Scientific Work Is Untested

Scientific research is critical to finding solutions to the CWD problem, and many potential solutions and techniques are being investigated and tested, including genetics. However, to date the “resistant deer” idea is based on a single study that was conducted through artificial intelligence. It should be investigated through actual animal experimentation, like any other potential solution, before it is tested on wild deer in the real world. We must be confident any tactics we deploy against CWD will not worsen the situation.

These factors above help explain why most professional wildlife biologists see “resistant deer” as a false hope in the fight against CWD.

What Others Are Saying

Oklahoma’s House Bill 3462 was opposed by the National Deer Association, the Rocky Mountain Elk Foundation, the Mule Deer Foundation, the Boone & Crockett Club, the Pope & Young Club, the Teddy Roosevelt Conservation Partnership, the National Wildlife Federation, and the Conservation Coalition of Oklahoma. Despite this, the bill passed the Oklahoma legislature and was signed into law by the governor of Oklahoma. Here are recent quotes from media coverage of the legislation as well as the larger question of genetic CWD resistance.

“While Pope and Young supports outside the box approaches dealing with CWD, we believe this bill being pushed through the Oklahoma Legislature is premature as the science is not conclusive enough to support law change.” –Justin Spring, Pope & Young Club Executive Director.

“We are skeptical that genetic research will lead us to a durable and applicable solution to the issues chronic wasting disease is causing in our deer herds nationwide, but are open to considering any viable paths forward. Regardless, facilitating release of captive deer into the wild would do more harm than good when it comes to transmission of CWD.” – Tony Schoonen, Boone & Crockett Club CEO

“NDA is not opposed to research that may lead to stopping CWD in wild and even captive herds, and there may be value in the further study of deer genetics. We are opposed to going from step one to 100 without the benefit of peer-reviewed science to avoid unintended consequences.” – Nick Pinizzotto, National Deer Association President and CEO

“One of the biggest problems with the captive deer industry is that there’s not a practical and reliable live animal test. Deer that are CWD-positive are unknowingly moved from facility to facility right now. This will be catastrophic if those deer are unknowingly moved into the wild.” –Kip Adams, wildlife biologist and NDA Chief Conservation Officer, from the article Can We Breed Our Way Out of CWD? Oklahoma Wants To Try.

“At NDA, we want to find solutions to the CWD problem more than anyone else out there, but in looking and hoping for those solutions, we have to be certain we’ve found one before diverting time and money away from more meaningful projects trying to implement a plan that will spread more disease to wild deer.” –Kip Adams, wildlife biologist and NDA Chief Conservation Officer, from the article Can We Breed Our Way Out of CWD? Oklahoma Wants To Try.

“The longer an infected deer lives, the more contact it will have with other deer, and the more prions it will shed on the landscape. CWD prevalence in that herd would likely go up and you’d get more infections in younger deer. And if that happens, those younger deer would spread it farther and faster when dispersing.” –Mike Samuel, professor emeritus, University of Wisconsin-Madison, from the article Can Science Breed CWD Out of Deer? Not Likely

“It’s a pie-in-the-sky hope. No one has documented a deer surviving CWD, so no one has a truly CWD-resistant deer. Some deer take longer to get CWD, and they might live longer once they get it, but they still get CWD and it still kills them. So how can anyone say they can selectively breed more of something that doesn’t exist?”  –Dr. Krysten Schuler, Cornell Wildlife Health Lab, from the article Can Science Breed CWD Out of Deer? Not Likely

“These CWD-resistant genotypes aren’t found frequently in natural populations. The most CWD-resistant genotypes occur at very low rates, and there’s probably a reason for that. Those genotypes might carry traits that cause other population-limiting problems not yet documented.” –Dr. Krysten Schuler, Cornell Wildlife Health Lab, from the article Can Science Breed CWD Out of Deer? Not Likely

“In experimental challenge studies all deer with 96S or 225F alleles contract CWD, but the presence of 96S or 225F, respectively, extends the incubation period. Although a prolonged incubation period may allow additional time for CWD-positive deer to reproduce, it also increases opportunities for disease transmission and may allow disease prevalence to rise to a new equilibrium within endemic regions.” –Update for the North American Wildlife and Natural Resources Conference from the USGS National Wildlife Health Center.