Rabbits in Fort Collins, Colorado, have recently been spotted with eerie, unusual growths that resemble tentacles or horns protruding from their heads and faces. These bizarre appearances are caused by an infection known as Shope papilloma virus (SPV), a disease that triggers wart-like, keratinous growths on rabbits. The virus is related to the human papillomavirus (HPV) and primarily affects cottontail rabbits native to the Midwest, though outbreaks have been noted in domestic rabbits as well. Residents, including Susan Mansfield, have described these growths as looking like black quills or toothpicks sticking out around the rabbits’ mouths, creating an uncanny resemblance to the mythical jackalope creature popularly depicted with antlers or horns.

The Shope papilloma virus is transmitted mainly through biting arthropod vectors such as mosquitoes and ticks, although close contact with infected fluids can also facilitate its spread among rabbits. While the virus causes striking and sometimes alarming growths, it is species-specific and does not pose a threat to humans, dogs, or other wildlife. Colorado Parks and Wildlife officials have reassured locals that the growths themselves do not carry the virus, so there is no risk of contagion to people or pets. However, they caution against approaching or handling affected rabbits, as these wild animals should be given space, like any other wildlife.

The impact on the rabbits varies depending on the size and location of the growths. In most cases, the growths are benign and do not harm the rabbits. However, larger growths near sensitive areas, such as the eyes or mouth, can interfere with the animal’s ability to see or eat, potentially leading to more serious health complications. The virus can persist for years, and in some cases, the growths may evolve into malignant tumors, posing a greater risk to infected rabbits. Despite this, many affected rabbits continue to survive for multiple years with the condition, as one Fort Collins resident observed a rabbit with these growths return for a second year.

Historically, SPV is believed to be the inspiration behind North American folklore of horned rabbits or jackalopes, blending natural phenomena with storytelling. The discovery of the virus in the 1930s contributed to medical science’s understanding of virus-induced cancers, serving as a model for HPV research. Today, while the virus remains incurable, it is monitored by wildlife officials to track its spread and impact. Public awareness and cautious observation help protect both the animals and people in communities where these unusual rabbits are sighted.