DENVER (KDVR) — If you’ve seen rabbits north of Fort Collins with unusual wart- and tentacle-like growths on them, you’re not alone, but officials say it’s not something to worry about.

Colorado Parks and Wildlife noticed it as well and says that it’s not that rare.

The black, twisted growths seen on Colorado rabbits come from the papillomavirus and are spread by biting insects that are more active in warmer months. The bites spread the viral disease and cause malignant tumors to grow in rabbits, often on their heads.

CPW says there’s no threat of transmission to pets, but is still warning residents to be careful.

“There’s no overt concern needed for pet owners, we would just say to keep those wildlife principles in mind when you do have them out: Keep them on leash, keep them away from wild animals just in case, but it is not something necessarily we see transferred from rabbits to dogs,” said CPW spokesperson Kara Van Hoose.

CPW also said that the rabbits can fight off the virus on their own, and the agency only gets concerned when the growths cover their eyes or impact their ability to eat.

Copyright 2025 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.