Colorado Officials Warn Public to Avoid ‘Frankenstein’ Rabbits Carrying Rare Virus
Colorado Parks and Wildlife (CPW) is warning residents to keep their distance from so-called “Frankenstein” rabbits—wild cottontails infected with a rare virus that causes strange horn-like growths on their heads and faces.
The unusual appearance, sometimes described as black quills or spikes, is caused by the cottontail papilloma virus (CRPV), also known as Shope papilloma virus. The virus triggers tumor-like growths that can harden into keratinized protrusions, giving the animals their alarming nickname.
Sightings in Colorado date back at least to 2024, when a resident reported seeing a rabbit with its mouth surrounded by black, toothpick-like spines. Some infected rabbits have been observed surviving through multiple seasons, with the growths increasing over time.
While CPW says the virus is not believed to spread to humans or pets, officials are urging the public not to touch the animals or attempt to help them. CRPV spreads mainly through mosquitoes and ticks that bite infected rabbits, although it can also be transmitted between rabbits in rare cases.
The virus first presents as small, red raised spots on the skin, which later develop into wart-like tumors and sometimes large, horn-shaped growths. Researchers note that while the current outbreak has been most visible in Colorado, cottontail rabbits across the Midwest could also be susceptible.
Authorities advise anyone who encounters an infected rabbit to keep a safe distance and contact local animal control rather than approaching.
