Attack of the Frankenbunnies: The Real Science Behind Rabbits Growing Tentacles in the U.S.
- Jomanda Heng
- Aug 19
- 2 min read
They hop. They twitch their noses. And now… some of them appear to grow tentacles. Residents in Fort Collins, Colorado, have been startled by wild rabbits sporting black, spiky growths sprouting from their faces—leading some to dub them “Frankenbunnies.” But while the look might scream science fiction, the explanation is firmly grounded in science.
The strange growths are caused by Shope papillomavirus (SPV), a rabbit-specific infection first discovered in the 1930s. This virus triggers keratinized, wart-like tumors that can twist into horn- or tentacle-like shapes, especially around the head and face. The eerie appearance is so striking that many believe it inspired the American tall tale of the horned jackalope.
Frankenbunnies: How Many States Are Affected?
The recent buzz is centered in Colorado, but experts stress that SPV is not a new outbreak and isn’t confined to one region. The virus has been documented for decades across much of the Midwest and other parts of the U.S., often surfacing in warmer months when ticks and fleas—its main carriers—are more active.
While only a handful of sightings get reported each year, wildlife biologists say the virus could be quietly present in multiple states at any given time, affecting wild rabbit populations far beyond Colorado.
Can Humans or Pets Catch It?
Here’s the good news: SPV can’t infect humans, dogs, or cats. It’s entirely species-specific to rabbits. The virus spreads via biting insects or direct contact between rabbits, and while it can’t jump species, domestic rabbits can catch it if they’re exposed outdoors.
For pet rabbits, the growths can become more severe—sometimes obstructing vision or eating, and in rare cases, turning cancerous. Veterinarians recommend keeping rabbits indoors or using insect-proof enclosures to reduce the risk.
Why It Looks So Creepy
SPV growths are usually hard, dark, and often bent or twisted—earning nicknames like “devil horns” and “black toothpicks.” In the wild, the growths may eventually fall off, but severe cases can impact a rabbit’s ability to survive. Wildlife officials typically advise leaving infected rabbits alone, as most manage without human intervention.
Yes, they look like something dreamed up by a horror director. No, they’re not a threat to people. The Shope papillomavirus has been part of nature’s strange playbook for nearly a century, and while it may occasionally shock us with its visuals, it’s more curiosity than crisis.
Sometimes, the wildest stories in nature don’t need to be exaggerated—they’re already stranger than fiction.
References:
The Uncommon Breed
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