Frankenstein-Like Growths in US Rabbits Traced to a 90-Year-Old Virus

Rabbits across several states—including Colorado—are developing dark, tentacle-like growths on their heads due to Shope papillomavirus (SPV), a rabbit-specific infection that has been known since the 1930s. The growths are wart-like and most infected rabbits survive; in severe cases they can progress to squamous cell carcinoma and impair vision or eating. SPV is not known to infect humans, but domestic rabbits can catch it from wild carriers or vectors such as mosquitoes, ticks, and fleas, so pet owners should keep rabbits indoors or in screened enclosures, control pests, avoid contact with wild rabbits, and seek veterinary care if suspicious growths appear. The virus historically aided cancer research and HPV vaccine development, underscoring why this isn’t a human health threat despite the eerie visuals.