Every summer, social media fills with unsettling images of backyard wildlife that look more like extras from a low-budget horror movie than neighborhood critters. This year, it’s squirrels with grotesque sores and rabbits sprouting what appear to be black, tentacle-like horns from their heads. While the sight is shocking, scientists say these conditions are less terrifying than they appear—and in many ways, they’re teaching us important lessons about viruses, immunity, and even human health.In northern Colorado, residents recently spotted wild rabbits with twisted, horn-like growths protruding from their faces. Reports came in from Fort Collins, where some of these animals looked like they had sprouted black tentacles instead of fur.What Are Frankenstein Rabbits?Colorado Parks and Wildlife (CPW) quickly confirmed the culprit- Shope papillomavirus, a virus first identified in the 1930s. The infection causes keratin-based growths made of the same material as human nails and hair—that can grow into elongated, horn-like shapes.For most rabbits, the infection is temporary. “They’re able to clear it from their system on their own,” says Kara Van Hoose, CPW spokesperson. Once the immune system suppresses the virus, the horns dry out and eventually fall off. But in some cases, the growths can interfere with eating, foraging, or even vision. Rarely, they can develop into squamous cell cancers.Importantly, Shope papillomavirus only infects rabbits and hares—not humans or pets. The growths themselves aren’t contagious. Instead, the virus spreads via bites from mosquitoes, fleas, and ticks, which is why sightings spike in summer and then fade with the first frosts.A Virus with A Surprising LegacyThe rabbit virus may look like a strange wildlife quirk, but its scientific significance is immense. Richard Shope, the virologist who identified it in 1933, later contributed to research on influenza A and traced links to the deadly 1918 flu pandemic.Even more importantly, his studies of rabbit papillomavirus helped scientists understand human papillomavirus (HPV), a pathogen now known to cause several cancers. This research eventually led to the development of the HPV vaccine, one of the most effective tools in modern cancer prevention.In other words, the bizarre-looking horned rabbits of Colorado are part of a story that connects animal health, human medicine, and the fight against one of the world’s leading cancer-causing viruses.What Are Zombie Squirrels?If the horned rabbits weren’t alarming enough, homeowners across the U.S. and Canada have reported squirrels with grotesque, oozing sores. Dubbed “zombie squirrels” on Reddit and local news outlets, these animals often appear bald, scabby, and covered in tumors.At first, some feared this was squirrelpox, a rare and often deadly virus primarily found in red squirrels in the U.K. But experts now say that in North America, most cases are actually squirrel fibromatosis, caused by a virus called leporipoxvirus.Like the rabbit papillomavirus, fibromatosis creates wart-like growths that may burst and ooze fluid. The disease looks disturbing, but it usually clears up on its own within four to eight weeks. Gray squirrels, which are common across the U.S., generally recover fully.How the Virus Spreads Among Animals?Unlike the horned rabbit virus, which is spread by biting insects, squirrel fibromatosis spreads through direct contact with infected saliva or lesions. That means the backyard bird feeder—a favorite stop for squirrels—can act as a transmission hub. Infected squirrels may leave saliva on seeds, which is then picked up by others.“Shevenell Webb, a wildlife biologist in Maine, explains it like this: ‘It’s like when you get a large concentration of people. If someone is sick and it spreads easily, others are going to catch it.’”Although it’s upsetting to see squirrels in such poor condition, the disease does not spread to humans, dogs, or cats. Experts strongly advise against touching or attempting to “rescue” infected squirrels.Should We Worry About Human Risk?Here’s the key point: Neither rabbit papillomavirus nor squirrel fibromatosis poses a risk to people. These viruses are species-specific, meaning they evolved to target only their animal hosts.That said, wildlife experts caution against close contact. Wild animals can carry other pathogens, and distressed animals can bite or scratch. The safest approach, they say, is observation from a distance.At first glance, these conditions look like nothing more than cruel tricks of nature. But the history of virology shows that studying animal viruses has repeatedly advanced human medicine. The rabbit papillomavirus directly contributed to the eventual creation of the HPV vaccine. Even squirrel fibromatosis, though less studied, provides clues about viral behavior, transmission dynamics, and immune response.There’s also a conservation angle. Tracking these conditions helps wildlife officials monitor population health and understand how environmental changes, including warmer summers and denser urban habitats, may amplify disease spread.It’s worth noting that both the horned rabbits and zombie squirrels came into the public spotlight through viral photos online. Platforms like Reddit and X (formerly Twitter) have become informal early-warning systems for unusual animal illnesses. While this sometimes fuels fear, it also provides wildlife agencies with useful crowd-sourced data.As Van Hoose points out, it’s difficult for agencies to know whether multiple sightings represent several infected animals or just the same one seen repeatedly. Public reports when paired with expert analysis help build a clearer picture.What to Do If You Spot A ‘Frankenstein Rabbits’ or ‘Zombie Squirrels’?If you see a rabbit with horns or a squirrel with sores, the advice is straightforward:Do not touch or feed the animal.Do not attempt to trap or euthanize it.Report sightings to local wildlife authorities if requested in your area.These animals, though unsightly, are usually not suffering long-term. Many recover naturally once their immune system clears the virus.From rabbits with keratin “horns” to squirrels with wart-like sores, these strange cases highlight how deeply intertwined wildlife health is with human understanding of disease. They remind us that viruses are not just human problems—they shape ecosystems, influence evolution, and sometimes, unexpectedly, lead to breakthroughs that save lives.