In Fort Collins, Colorado, residents are encountering wild rabbits with grotesque, tentacle-like growths sprouting from their heads and faces. The disturbing appearance has drawn comparisons to fictional monsters, yet the cause is rooted in a very real virus.
The culprit is the Shope papilloma virus, a close relative of the human papillomavirus. It triggers keratin-based tumors that can emerge as horn-like or spiny protrusions on a rabbit’s skin. These growths can cluster around the mouth, eyes, and head, creating a nightmarish effect. Wildlife officials say the infection, while visually shocking, is harmless to humans and other animals, but dangerous for the rabbits themselves.
How the Virus Works
According to experts with Colorado Parks and Wildlife, the virus is transmitted primarily by biting insects such as mosquitoes, ticks, and fleas. The growths themselves do not carry the virus, but once an insect feeds on an infected rabbit, it can transfer the virus to others through subsequent bites, TODAY.com reports.
The disease usually begins with small, red, raised lesions that grow into dark, keratinized masses. As UNILAD notes, some rabbits can clear the virus on their own, but if growths develop over the mouth or eyes, they can interfere with eating, drinking, or seeing, eventually leading to starvation or death.
Wild rabbits in Fort Collins, Colorado, are developing black, tentacle-like growths.
Witness Accounts and Local Concern
Longtime Fort Collins resident Susan Mansfield described one infected rabbit as looking like “black quills or black toothpicks sticking out all around its mouth.” She told local news that she assumed the animal would not survive the winter, but it returned the following year with even larger growths.
Another local reported seeing a “scabbiesh-looking growth” covering part of a rabbit’s face, highlighting the variety in how the virus manifests. These sightings have stirred unease among residents, even though wildlife officials stress there is no risk to people.
Origins and Scientific Significance
Shope papilloma virus has been documented since the 1930s and has played a role in cancer research. Its discovery helped confirm that some viruses can cause malignant tumors, and scientists have used it as a model for studying virus-induced cancers in humans, Gizmodo reports.
The strange, antler-like shapes these growths sometimes take may also be behind the North American folklore of the jackalope. The uncanny resemblance to antlered rabbits likely inspired early myths, later commercialized by taxidermists in the mid-20th century.
Impact on Domestic and Wild Rabbits
Infections are most common in wild cottontail rabbits, though domestic rabbits can be affected if bitten by an infected insect. In such cases, veterinarians can surgically remove growths before they become cancerous. In the wild, however, infected rabbits face a harsher fate. Without intervention, the expanding masses can make it impossible to feed, leading to slow decline.
Officials urge pet owners to keep rabbits indoors or in screened enclosures during peak mosquito activity. Wild rabbits should be given space, as stressed by Colorado Parks and Wildlife. While the virus cannot cross to humans or other species, approaching any sick wild animal poses unnecessary risks.
Photo: YouTube / E! News
The cause is the Shope papilloma virus, a cousin of human papillomavirus.
Why the Sightings Are Increasing
Late summer insect activity likely fuels the recent uptick in cases. As more biting insects interact with infected hosts, the virus can spread across local rabbit populations. Though the disease has been present for decades, clusters of cases like the one in Fort Collins tend to attract attention due to their unsettling visual impact, amplified by viral photographs and social media.
For residents, the sight of these so-called “Frankenstein rabbits” is alarming. For wildlife professionals, it is a reminder of how viruses can shape — and sometimes distort — the natural world in ways that capture both scientific interest and public concern.
