In the quiet suburbs of Fort Collins, Colorado, ordinary rabbits are taking on an extraordinary — and unsettling — appearance. Once familiar creatures of the wild, some rabbits are now growing black spikes and tentacle-like growths on their faces, baffling residents and scientists alike. The culprit? A rare virus that is transforming these common animals into what many are calling “mutant rabbits,” and sightings are becoming increasingly frequent.
Reports began in 2024 when a resident posted a photo online showing a rabbit’s entire head covered in black, spike-like growths.
A witness, Susan Mansfield, told 9News that she recently saw a rabbit with black spines or “feathers” around its mouth.
“It looked like it had black spikes or toothpick-like structures all over its mouth,” Mansfield said. “I thought it would die over the winter, but it didn’t. It came back the next year — and had grown even bigger.”
According to the Daily Mail, the rabbits are infected with the Shope papillomavirus (CRPV), which causes tumors to grow on or near the animal’s head.
The Colorado Parks and Wildlife Department (CPW) has warned anyone who sees infected rabbits to keep their distance and avoid touching them.
CPW does not believe the virus can be transmitted to humans or pets, but it still urges the public to avoid contact and not attempt to help the rabbits.
Although these “mutant” rabbits have been mostly seen in Colorado recently, researchers note that cotton-tail rabbits across the Midwest can also be infected with this rare virus.
The CRPV spreads primarily through mosquitoes and ticks, which bite an infected animal and transmit the DNA-altering disease. Scientists have observed that the virus rarely spreads through direct contact between rabbits, and there are no known cases of insects infecting humans.
The first sign of infection is raised red spots on the skin, which eventually develop into wart-like tumors. In many cases, these warts evolve into keratinized papillomas — the “horns” and “tentacles” seen on Midwest rabbits.
In some cases, the warts can develop into squamous cell carcinoma, a serious skin cancer that can be fatal if not treated early.
For pet rabbit owners concerned about the virus, experts recommend preventing CRPV by keeping rabbits away from pests, especially mosquitoes. If a pet rabbit becomes infected, veterinarians can surgically remove tumors before they become malignant.
Occasionally, the growths heal on their own, but locals report that wild rabbits tend to develop increasingly larger “horns.”
The tumors can eventually grow large enough to interfere with the rabbit’s ability to eat, potentially leading to starvation. According to PetMD, the tumors usually develop on the ears, eyelids, or other parts of the head, sometimes making the animal nearly unrecognizable.
Some social media users have questioned whether euthanizing infected wild rabbits could prevent the spread.
“Is it more humane to put them down when they’re like this, or just leave them alone?” one Reddit user asked.
U.S. animal control authorities have not recommended euthanasia, emphasizing that the virus does not pose a public health risk.
Local wildlife officials stress that the best course of action when encountering these disfigured rabbits is to keep a safe distance and avoid disturbing them.
