A strange phenomenon is catching the attention of wildlife watchers: rabbits across Colorado are reportedly growing horn- and tentacle-like protrusions on their heads.
Nicknamed “Frankenstein rabbits” online, these unusual creatures raise questions—could it be a harmless virus, a genetic mutation, or something more concerning in the wild? Sightings are multiplying, and social media is buzzing with images that look like something straight out of a horror film.
The Rise of Horned Rabbits
Reports of bizarre rabbits have increased across the U.S., linked to a virus that transforms ordinary cottontails into grotesque, horned creatures. These growths—black and tentacle-like—have been especially common around Fort Collins, Colorado. The phenomenon first gained attention in 2024, when a local resident shared a photo of a rabbit whose entire head was covered in black, spike-like projections.
Susan Mansfield, a resident of Fort Collins, told 9News she recently spotted a rabbit with black “quills” around its mouth. “It looked like black toothpicks sticking out everywhere,” she said. “I thought it wouldn’t survive the winter, but it came back the next year—and it had grown even more.” Scientists have confirmed that these unusual growths are caused by the cottontail papilloma virus (CRPV), also called the Shope papilloma virus, which induces tumors on or around rabbits’ heads.
Safety and Spread
Colorado Parks and Wildlife (CPW) warns against touching infected rabbits. Although the virus is not known to infect humans or pets, it spreads primarily through mosquito and tick bites between infected rabbits. Direct contact between rabbits rarely transmits the virus, and there are no documented cases of humans contracting it via insects.
Initial signs of CRPV include raised red patches that develop into wart-like growths. These keratinized tumors form the “horns” and “tentacles” seen by observers. In severe cases, the growths can evolve into squamous cell carcinoma, a potentially deadly skin cancer. Veterinarians recommend protecting pet rabbits from biting insects and, if infected, removing tumors surgically before they become malignant.
Wild rabbits can grow large horn-like structures, although some growths may shrink naturally over time. Tumors can interfere with feeding, sometimes leading to starvation, and can also affect vision or hearing if located near the eyes or ears, according to PetMD. Social media users have debated whether euthanizing infected wild rabbits might help control the virus. U.S. animal control experts, however, stress that the virus is harmless to humans and do not recommend culling. Observing from a safe distance remains the best approach.
Folklore Connection
Historically, stories of the mythical “jackalope”—a rabbit with antelope-like horns—may have roots in cases of CRPV infection. Illustrations and reports of horned rabbits appear in texts dating back to 1789, including the Tableau encyclopédique et méthodique.
Conclusion
The emergence of CRPV-infected rabbits highlights a fascinating intersection of wildlife biology, folklore, and viral mutation. While the appearance of these “Frankenstein” rabbits may be startling, experts emphasize that they pose no danger to humans.
By observing from a distance and avoiding contact, we can appreciate the unpredictable and sometimes eerie wonders of nature—reminders of how legend and reality can intertwine in the animal world.