In the context of Yellowstone's history and the popular culture surrounding it in 2026, "the cows" (specifically cattle in the Greater Yellowstone Ecosystem) are most famous for contracting Brucellosis. This is a highly contagious bacterial disease that was originally introduced to North American wildlife by European livestock in the early 20th century. Today, it persists in the park's wild bison and elk populations. The "drama" arises because Brucellosis causes cattle to miscarry their calves, leading to devastating economic losses for local ranchers. In 2026, this remains a point of heavy contention; when bison migrate out of park boundaries into Montana, they are often strictly managed or culled to prevent them from coming into contact with domestic "cows." While there are no "wild cows" living permanently inside Yellowstone, the interaction between the park's protected wildlife and the surrounding ranching industry is a central theme in both real-world environmental policy and the fictional Yellowstone television series, where "the cows" are often the catalysts for legal and physical conflict.