The Guts of Predatory Cats Can Destroy CWD Prions

June 21, 2023 By: Lindsay Thomas Jr.

Chronic wasting disease prions are the Chuck Norris of infectious materials. Incinerating them at 1,112°F will only slightly degrade their infectivity, and you must hit 1,800°F to destroy them. They are just fine left out in the environment for years, outside an animal host, without losing infectious potential. They can even survive a trip through the guts of coyotes and crows and still infect deer. It’s tough to kill something that isn’t really living to begin with.

But we can now lengthen the short list of things that destroy CWD prions. A trial with mountain lions and a separate study with bobcats – neither of which appear to be susceptible to CWD infection – found only about 2 to 3% of the prions that entered the front ends of these cats made it out the back ends. Both studies were shared recently at the International CWD Symposium in Denver.

The Mountain Lion Study

Chase Baune of the National Institute of Allergy and Infectious Diseases in Montana led a study in which two captive mountain lions were fed ground mule deer spiked with CWD prions. 

“We recovered only 2.8 to 3.9% of input CWD prions after passage through the mountain lions’ gastrointestinal tracts,” Chase wrote in his report. “Interestingly, CWD prions were shed only in the first defecation following consumption. Our data… suggest that most of the ingested prions are eliminated or sequestered by this large predator.”

Rapid excretion is a good thing, because mountain lions tend to stay close to a deer or elk carcass for days as they consume it. Though their digestive tracts appear to be destroying 96% or more of the prions they eat, the few that make it through aren’t likely to be scattered far from the kill site. Chase also pointed to other studies showing mountain lions tend to select CWD-infected mule deer over healthy prey. All this means mountain lions may be a helpful though minor factor in western outbreak zones by targeting infected deer and elk and then digesting many of the infective prions they are carrying.

Madi Davis of the University of Wyoming presented her bobcat study as a poster display at the International CWD Symposium in Denver.

The Bobcat Study

In a similar study at the University of Wyoming, graduate student Madi Davis fed ground beef spiked with CWD-positive elk lymph nodes to three bobcats. A fourth bobcat, the “control,” was fed the same beef without the infective CWD material. Madi recovered less than 2% of the CWD prions from the three study bobcats. She is moving on to new tests using whole deer and elk brains and then whole carcasses fed to the four bobcats.

“I also now want to determine the stability of these prions left in the bobcat’s poop because there could be a chance that the 2% we are recovering is a lot less stable in the environment compared to what a deer is shedding,” said Madi.

Where Did the CWD Prions Go?

What is happening to the vanishing prions in both cat species? In the mountain lion study, examination did not locate prions collecting in the cats’ bodies or organs, which suggests the missing prions must have been fully digested. I asked Madi the same question about the bobcats.

“After talking with a few other scientists, my theory is that bobcats and other obligate carnivores have more enzymes in their GI tract that can degrade proteins,” said Madi. “I also think that the microbiome of these animals could potentially contribute to this degradation as well, but I suspect that it is less likely than the digestive enzymes. I’m hoping that I can test these theories in a few years.”

This deer was not killed by a bobcat. NDA member Gil Lackey used the carcass of a buck he killed as bait for his trail-camera and caught this bobcat scavenging meat. Bobcats are not significant predators of adult deer, but as this photo shows they will scavenge dead deer.

Obligate means these cats require an almost total meat diet for nutrition, unlike coyotes which eat a wide range of fruits and other foods. Therefore lion and bobcat digestive systems may be more efficient at digesting proteins, which includes CWD prions.

Feline Friends in the Fight

While bobcats are far more numerous and widespread than mountain lions, and their range overlaps most of the whitetail’s, they are not significant predators of adult deer – though they will scavenge deer carcasses. It’s likely CWD-infected deer are more susceptible to bobcats than healthy deer, but still not likely bobcats are a significant factor in slowing the spread of CWD.

Nevertheless, when we know so little about prion diseases, every new piece of knowledge adds to the picture, and we’ll take good news when we can get it. When we know so few things that can destroy CWD prions, it’s good to add mountain lions and bobcats. We need all the allies we can get, so please welcome Lynx rufus and Puma concolor to the fight.

Visit our CWD Resource Center for more information about this disease.

About Lindsay Thomas Jr.:

Lindsay Thomas Jr. is NDA's Chief Communications Officer. He has been a member of the staff since 2003. Prior to that, Lindsay was an editor at a Georgia hunting and fishing news magazine for nine years. Throughout his career as an editor, he has written and published numerous articles on deer management and hunting. He earned his journalism degree at the University of Georgia.