Pictures of 'zombie-rabbits' with twisting black horns go viral - so are they real?

Photos of rabbits in Colorado with black, horn-like growths around their faces have gone viral, with some describing the animals as "Frankenstein-", "zombie-" and "demon-rabbits".

Warning: This article contains images of infected rabbits, which some readers may find disturbing.

Residents in Fort Collins near Denver recently began posting pictures of the cottontail bunnies, causing a stir online.

"This is how the zombie virus starts," posted one Instagram user on a post showing the rabbits.

"We've got freaking zombie rabbits now?!" posted another on YouTube.

So what's going on?

Firstly, the pictures are real - despite some wishing they weren't.

"One time I need this to be AI," wrote one Instagram user on a post showing the horned bunnies.

The rabbits are suffering from a relatively harmless disease called Shope Papilloma Virus, according to Colorado Parks and Wildlife.

Although the wildlife agency is getting calls from people spotting the infected rabbits in Fort Collins, they're not an unusual sight, according to spokesperson Kara Van Hoose.

The disease is mainly found in America's Midwest, according to the University of Missouri, and is more noticeable in the summer, when the fleas and ticks that spread the virus are most active.

The virus can also spread through rabbit-to-rabbit contact but not to other species like humans or dogs and cats, according to Ms Van Hoose.

People are being warned not to touch the infected rabbits, however.

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Do the growths hurt the rabbits?

The horn-like growths, or papillomas, are harmless to the bunnies, unless they grow on sensitive areas like the eyes or mouth or interfere with eating.

Once the rabbits' immune systems have fought the virus, the growths will disappear.

Although infected wild rabbits usually don't need treatment, it can be dangerous to pet rabbits, so officials recommend getting pet bunnies treated by a vet.

The mythical jackalope

It's not a new illness, and is even thought to have inspired the centuries-old myth of the "jackalope", a rabbit with antelope antlers.

Although hunters had long known about the disease, it was first scientifically reported in 1931 by Richard E Shope - hence the name.

Since then, the rabbits' warts and horns have contributed to life-saving scientific understanding, including how viruses can be linked to cancer, like the HPV virus to cervical cancer.