The rabbits reported around Fort Collins in August 2025 most likely had Shope papillomavirus, also called cottontail rabbit papillomavirus. It can cause keratin-rich, wart-like skin growths that elongate into hornlike projections, but “tentacles” is a description, not a medical term.
Colorado Parks and Wildlife (CPW) says the virus is not uncommon in Colorado, spreads among rabbits through biting insects, and does not infect people or pets. Growths often recede, though ones near the eyes or mouth can interfere with a rabbit’s ability to see or eat.
What happened in Fort Collins?
Unusual rabbits reported in the Fort Collins area drew attention in August 2025. Their dark, elongated growths were described in news coverage as horns, quills, or tentacles. The reports were consistent with rabbit papillomavirus, but the sources do not establish that every photographed rabbit was laboratory-confirmed to have the virus.
CPW reportedly received about a dozen reports, while cautioning that multiple reports could refer to the same rabbits. That figure does not establish the number of distinct infected animals or how common the condition is across Colorado. CPW said the virus was not new or uncommon in the region; the 2025 attention was a news event, not evidence of a new outbreak.
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What are the growths?
They are wart-like skin growths, or papillomas. The growths contain keratin, the material that makes up hair and nails, and can become elongated and hard-looking. In photographs, they may resemble black quills, horns, or tentacles, especially when they appear around a rabbit’s face.
“Tentacles” is a striking shorthand, but “hornlike skin growths” or “wart-like growths” is more accurate.
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What causes rabbit papillomas?
The likely cause in the reported rabbits is Shope papillomavirus, also called cottontail rabbit papillomavirus. It affects rabbits and hares. Although it belongs to the papillomavirus family, it is not human HPV: CPW says it does not spread to people or pets.
How does it spread?
Biting insects, including fleas and ticks, can transmit the virus among rabbits. CPW spokesperson Kara Van Hoose told the Associated Press that infected rabbits are especially likely to be seen in summer, when fleas and ticks are active. The public reports do not identify how any particular Fort Collins rabbit became infected.
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Is the virus dangerous to people or pets?
| Who | What the research says |
|---|---|
| People | CPW says the virus does not infect humans. |
| Dogs and cats | CPW says it does not infect pets. Keep pets from chasing or handling wild rabbits. |
| Rabbits | The virus spreads among rabbits. Growths often recede, but ones near the eyes or mouth can interfere with function, especially eating. |
Do not handle a wild rabbit, even if its growths look familiar from news coverage. Observe it from a distance and contact local wildlife authorities if it appears injured or unable to eat.
Do the growths hurt or kill rabbits?
CPW says the growths generally do not harm rabbits unless they grow near the eyes or mouth and interfere with eating. They often recede when the rabbit’s immune system clears the infection. A growth’s appearance alone cannot show whether a specific rabbit is ill or how its condition will develop.
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What should you do if you see one?
- Keep your distance. Observe the rabbit without approaching, chasing, or handling it.
- Keep pets away. Do not let dogs or cats approach or catch the rabbit.
- Do not try to treat it. Do not capture the animal or apply medication or pet products.
- Contact local wildlife authorities about an injured animal. Seek advice if the rabbit appears unable to eat or see, or is otherwise in clear distress.
Why did the story go viral?
The growths are unusual-looking, and pictures of them spread widely in 2025. The virus also has historical scientific interest: The Wildlife Society reports that studies of it date to 1933 and describes its place in the history of research on virus-associated cancers.
Some accounts connect rabbit papillomas with jackalope folklore, but this is a possible cultural connection, not a proven origin story.
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Frequently Asked Questions
Do rabbits really have tentacles growing from their faces?
No. The projections are skin growths that can become elongated and hornlike. “Tentacles” is a descriptive label, not a biological term.
Can people, dogs, or cats catch Shope papillomavirus?
CPW says the virus does not infect people or pets. Still, keep your distance from wild rabbits and do not let pets approach them.
Will an affected wild rabbit recover?
The growths often recede as the rabbit’s immune system clears the infection. Growths near the eyes or mouth can interfere with seeing or eating.
What should I do if I see a rabbit with these growths?
Observe it from a distance, keep pets away, and do not handle or treat it. Contact local wildlife authorities if it appears injured or unable to eat.
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Bottom line
The Fort Collins rabbits reported in August 2025 most likely had papillomas caused by Shope papillomavirus. The growths can look like horns or “tentacles,” but they are keratin-rich skin growths. CPW says the virus spreads among rabbits through biting insects, does not infect people or pets, and usually causes growths that recede unless they interfere with the eyes or mouth.
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