2023: First North American mountain lion identified with "staggering disease" (RusV).

In a rare case, a Colorado mountain lion has become the first one in North America identified as having contracted "staggering disease," a usually fatal neurological syndrome most typically seen in domestic cats. The mountain lion, which was euthanized in May 2023 due to being unable to use its hind legs, was found to have the rustrela virus, or RusV. This is the first recorded case of the disease in the species in North America.