New Study Finds “Staggering” Disease in Colorado Mountain Lion

In May of 2023, Colorado Fish and Wildlife was alerted to a peculiar-acting mountain lion in a residential area just south of Denver. The cat was displaying signs of severe hind leg ataxia and paresis (he couldn’t bear weight or stand on his hind legs) and was seen dragging itself along using only its front legs. State wildlife officials made the call to first tranquilize the cat before shooting it in the chest in an effort to preserve neural tissue. 

Given the unique condition of the animal, the corpse was promptly shipped out to Colorado State University College of Veterinary Medicine and Biomedical Sciences for a full panel including necropsy,  histopathology, immunohistochemistry, molecular diagnostics, and metatranscriptome sequencing to investigate potential causes of the disease.

Following the investigation and analysis, researchers confirmed the presence of the rustrela virus, which was recently identified as the cause of “staggering disease,” a usually fatal neurologic syndrome recognized in domestic cats. According to the paper, the diagnosis was not one that came easy as former CPW Wildlife Pathologist Dr. Karen Fox noted that the final confirmation was only possible through collaboration with researchers at the Friedrich-Leoffler-Institut in Germany.    

Now working as a research scientist with Colorado State University, Fox stated that scientists are unaware as to how widespread this particular virus is, but did confirm that it has been known to affect cats along with a number of other species including rodents and marsupials.

“Now that we know what we’re looking for, it should be easier to find new cases if they are out there,” Fox said. “With continued collaboration, we plan to learn what we can from our colleagues in Europe while we continue to look for new cases of staggering disease here in Colorado.”

Meanwhile, officials will continually be on the lookout for new possible cases and are recommending that any observations of mountain lions staggering or having trouble walking should be reported to Colorado Parks and Wildlife.