Virus-affected rabbits in Colorado are growing strange "horns". Scientists insists there's no cause for alarm.
In the picturesque state of Colorado, a peculiar outbreak has been reported, affecting local cottontail rabbits. The disease, known as the Shope papillomavirus, causes wart-like growths on rabbits, sometimes resembling horns or tentacles, primarily on their faces [1][2].
This virus, first identified by cancer researcher Richard E. Shope in the 1930s, has been used as a scientific model to study human papillomavirus (HPV) due to similarities in disease manifestation [1]. In Colorado, especially around Fort Collins, the virus causes visually alarming growths on cottontail rabbits, leading to nicknames such as "zombie" or "horned" rabbits due to their grotesque appearance [1].
The growths come from the papilloma virus and are typically spread by biting insects, which are more active during summer months [2]. Despite their appearance, the disease is often benign—many rabbits are able to fight off the virus and recover naturally [1]. There is no threat of transmission to pets or humans reported, but wildlife officials recommend keeping pets away from wild animals as a precaution [2].
Susan Mansfield, a Fort Collins resident, described seeing one of the infected rabbits as having black growths protruding from its mouth. The growths on rabbits do not harm them unless they grow on their eyes or mouths and interfere with eating [1]. Residents of Fort Collins have been posting pictures of the infected rabbits, causing the news to gain attention.
The virus in rabbits has contributed to scientists' understanding of the connection between viruses and cancer, such as the human papillomavirus that causes cervical cancer [1]. It is important to note that the Shope papillomavirus cannot spread to humans, pets, or other species, except from rabbit to rabbit.
Colorado Parks and Wildlife has been receiving calls about the infected rabbits in Fort Collins, and the public is encouraged to report any sightings. As the summer months approach, it is crucial to be aware of this unusual outbreak and take necessary precautions to ensure the safety of both wildlife and pets.
References:
[1] Colorado Parks and Wildlife. (2025). Shope papillomavirus outbreak in Fort Collins rabbits. Retrieved from https://cpw.state.co.us/learn/Pages/ShopePapillomavirusOutbreakinFortCollinsRabbits.aspx
[2] KUSA. (2025). Horned rabbits in Fort Collins spark concern among residents. Retrieved from https://kusa.com/news/local/horned-rabbits-in-fort-collins-spark-concern-among-residents
- The unusual outbreak of the Shope papillomavirus in Colorado's cottontail rabbits has gained attention in health-and-wellness and science news, as its similarities to human papillomavirus (HPV) contribute to medical-condition research.
- As summer approaches in Colorado, awareness of the Shope papillomavirus outbreak and the precautions to ensure the safety of both wildlife and pets is crucial, given its spread by biting insects and the visually alarming growths it causes in rabbits.
