Rabbits With Tentacle-Like Growth Around Head Reported in Colorado Neighborhood

Rabbits With Tentacle-Like Growth Around Head Reported in Colorado Neighborhood

2025 certainly has been an odd year for biology.

First, there were the radioactive wasp nests in South Carolina.

Next, China is experiencing a massive outbreak of mosquito-borne Chikungunya disease.  That’s on top of several of its “graduate students” being busted for bringing in biological samples illegally.

Now Colorado residents are reporting the appearance of wild cottontail rabbits with bizarre “horn-like” or “tentacle-like” black growths on their faces and mouths.

Residents in Fort Collins, Colorado recently noticed an unusual sight in their neighborhoods: rabbits with peculiar growths on their faces. Susan Mansfield, a resident in the area, described the appearance as “black quills or black toothpicks sticking out all around” the rabbits’ mouths, when speaking to reporters with KUSA.

“I thought he would die off during the winter but he didn’t, he came back a second year,” Mansfield said when speaking to KUSA.

The phenomenon has sparked curiosity and concern among locals, with some wondering if the rabbits are suffering from a contagious disease. However, Colorado Parks and Wildlife has confirmed that the condition is caused by a virus that is not contagious to other animals.

BREAKING; Experts Warn of Infected ‘Frankenstein’ Rabbits with Tentacles Invading the US.

These wild rabbits have been spotted hopping around with nightmarish facial growths across Fort Collins, Colorado. pic.twitter.com/QStFIQKNJz

— PulseX (@PulseX10) August 12, 2025

The rabbits are infected by the cottontail papilloma virus, also known as the Shope papilloma virus. This pathogen causes tumors to grow on or near the animal’s head, which continue to grow until the animal succumbs because it can no longer eat or see. This virus is spread mainly via mosquito and tick bites.

A member of the Papovaviridae family, this virus is frequently seen in cottontail rabbits, but may be contagious for other breeds. A rabbit suffering from Shope papilloma virus will have raised, red and rough lesions (usually circular), which are greater than one centimeter in length.

These lesions are found in various locations on the upper half of the animal’s body, including the neck and shoulders, but are primarily found on the eyelids, ears and other areas of the head. (They are occasionally seen on a rabbit’s feet.)

The lesions will continue to grow if left unchecked, turning into keratinized papillomas (the ‘horns’ and ‘tentacles’ seen rising out of midwestern rabbits).  Some of the wart-like growths can turn into squamous cell carcinoma, a potentially fatal skin cancer.

The virus is not transmissible to humans, but wildlife are warning people to avoid contact and be mindful of pets.

Colorado Parks and Wildlife (CPW) has urged anyone who sees infected rabbits to stay away and not touch them.

CPW does not believe the virus can leap to other species, such as humans or pets, but is still urging the public to avoid the rabbits and not attempt to help them.

Although these ‘Frankenstein’ rabbits have mainly been seen in Colorado recently, researchers noted that cottontail rabbits throughout the Midwest could become infected with the rare virus.

…For pet owners fearing their rabbits could contract the virus, medical experts said the best way to prevent SPV is to keep rabbits away from pests, especially mosquitoes.

If an insect bite does infect a pet rabbit with the virus, veterinarians can surgically remove the tumors before they become malignant.

Interestingly, the legend of the jackalope (a mythical North American creature described as a jackrabbit with antelope-like horns) is connected to the cottontail papilloma virus.  Infections lead to keratinous tumors resembling antlers or horns, much like those depicted in jackalope folklore.

In the 1930s, one scientist went in search of the origins of the myth. His discovery also advanced the understanding of human cancer.

Stories of the jackelope remain popular even today, especially around the Midwest where they were popularized, but the legend isn’t the only outcome of this strange phenomenon. In fact, there’s a connection to cancer.

Intrigued by the mystery behind the growths, cancer researcher Richard E. Shope investigated the rabbits and identified the cottontail rabbit papillomavirus (CRPV) as the cause. A few years later, Peyton Rous demonstrated that the virus could cause cancer.

This finding advanced human cancer research, too, and laid the foundation for studying human papillomavirus (HPV), a related virus with devastating effects, most commonly known to cause cervical cancers, of which there are about 11,500 new cases and from which about 4,000 women die annually in the U.S., according to the Centers for Disease Control and Prevention.

CRPV has long served as a stand-in for studying HPV. However, researchers at NCI Frederick and Pennsylvania State University Cancer Institute have only recently decoded its transcriptome—the complete map of its active RNA—revealing how CRPV’s RNA toggles genes on and off in host cells, allowing the virus to replicate and modulating the cells’ functions.

And that is the rest of the story.

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