Overview

• Colorado Parks and Wildlife has officially identified the black, horn- and tentacle-like facial growths on Fort Collins cottontail rabbits as keratinized papillomas caused by Shope papillomavirus.
• The DNA virus is specific to cottontail rabbits and cannot infect humans, although domestic rabbits kept outdoors remain vulnerable if exposed to infected wildlife or arthropod vectors.
• SPV spreads primarily through mosquito and tick bites and may develop into benign wart-like tumors that occasionally transform into malignant squamous cell carcinomas impairing feeding.
• There is no treatment for wild rabbits; veterinarians may surgically remove tumors in domestic rabbits and Colorado Parks and Wildlife recommends against handling or euthanizing wild animals unless they are suffering.
• Recent social media posts have intensified sightings, prompting wildlife officials to urge residents to observe affected rabbits from a distance and avoid interference.