In recent months, a wave of unsettling photos has spread across social media, showing deer with large, tumor-like growths bulging from their skin. The bizarre images have left many people worried that a new wildlife disease might be emerging in North America. The concern grew as similar deformities were reported not only on white-tailed deer, but also on rabbits and squirrels. Now, sightings in states such as New York, Pennsylvania, and Wisconsin have stirred widespread unease.
One Reddit user shared a photo of a Pennsylvania deer covered in disturbing growths and asked: “But what is the growth? Is it a mole? A boil? An injury?” The mystery spread quickly online, with speculation ranging from cancer to an unknown epidemic. Yet wildlife officials say the condition is not new at all—it is a long-documented viral infection known as deer cutaneous fibroma, more commonly referred to as “deer warts.”
What Are Deer Warts?
Deer cutaneous fibromas are caused by a virus in the papillomavirus family—the same group of viruses responsible for warts in humans. However, the strain affecting deer is specific to them and cannot infect people. Despite the grotesque appearance of the growths, experts stress that the condition has been recorded in the United States since at least the 1950s.
The virus spreads primarily through insects such as mosquitoes, ticks, and biting flies, which transfer infected blood between animals. It can also pass through direct physical contact with an infected deer or contaminated surfaces. Because ticks are known carriers, officials emphasize that while humans cannot catch deer warts, the same ticks can transmit dangerous illnesses such as Lyme disease.
Why the Growths Look So Alarming
Fibromas usually appear on areas such as the head, neck, and forelegs. They can range in size from small nodules to massive growths that cover large portions of a deer’s body. In most cases, they are not painful and will dry up and fall off naturally after a few months. But in severe cases, the growths can interfere with a deer’s ability to see, feed, or walk, making them vulnerable in the wild.
One social media user recounted seeing a deer with the condition in their own yard: “The warts got worse, then three months later, they were gone.” Such cases reflect the typical course of the virus—alarming at first, but often resolving without permanent damage.
A Climate Connection
While the fibroma virus itself is not new, experts warn that broader environmental changes may be amplifying its spread. Because mosquitoes and ticks are the main vectors, warmer temperatures and shifting climates are creating more favorable habitats for these insects. As a result, diseases that were once confined to certain regions are now appearing in new areas.
Lyme disease, also spread by ticks, is one such example. Cases have been steadily moving into regions of the U.S. where the illness was previously rare, raising fresh concerns about how climate change will continue to affect both human and animal health.
Viral Images, Old Virus
Although deer fibromas have existed for decades, the rise of smartphones and online sharing has brought the condition into public view like never before. Images of afflicted deer are more likely to circulate widely now, giving the impression of a sudden outbreak. In reality, experts say this is a long-standing and relatively common wildlife condition, one that looks frightening but rarely poses a significant threat to deer populations.
So while the photos continue to unsettle viewers, wildlife officials urge the public to take comfort in the facts. The virus is not new, it does not affect humans, and most deer recover naturally. What the images reveal, more than anything else, is how quickly a shocking sight can spark fear in the digital age.