Colorado Parks and Wildlife says a spate of wild rabbits photographed with black, horn-like growths on their heads is the result of cottontail rabbit papillomavirus, also known as Shope papillomavirus. The agency has logged multiple reports around Fort Collins and other parts of northern Colorado in recent weeks. The virus causes wart-like nodules that can elongate into quill- or tentacle-shaped protrusions. CPW spokesperson Kara Van Hoose said the growths are typically benign and do not harm the animals unless they obstruct the eyes or mouth, in which case wildlife officers may consider euthanasia. Officials emphasized that the virus is species-specific and poses no risk to humans, dogs or other wildlife. Domestic rabbits, however, can develop more severe cases and should be kept indoors or away from wild populations during warm months when fleas, ticks and mosquitoes spread the disease. There is no treatment beyond surgical removal of problematic tumors in pets, and most wild cottontails survive the infection until the growths recede naturally. CPW advises residents to avoid handling affected rabbits and to contact the agency only if an animal appears unable to eat or drink.