Wildlife officials are investigating why panthers and bobcats in three Florida counties are walking abnormally and having extreme difficulty controlling their back legs.

The cats appear to have no trouble using their front legs, but their hind legs crisscross and sometimes completely give out under their weight as they walk, causing them to stumble then struggle to continue walking, trail footage from counties of the west coast of southern Florida show.

The Florida Fish and Wildlife Conservation Commission (FWC) said Monday that the agency has confirmed neurological damage in one panther and one bobcat, while video footage captured in Collier, Lee and Sarasota counties show eight panthers and one bobcat demonstrating varying degrees of the leg condition.

Another panther photographed in neighboring Charlotte County could also be suffering from the condition, according to the FWC. The affected panthers in the video are mostly kittens, while the bobcat is an adult.

Wildlife officials are also reviewing video footage from other areas, but the problem seems to be localized.

“While the number of animals exhibiting these symptoms is relatively few, we are increasing monitoring efforts to determine the full scope of the issue,” said Gil McRae, director of the FWC’s Fish and Wildlife Research Institute.

McRae said experts have ruled out “numerous diseases and possible causes,” leaving the cause a mystery. “We’re working with the U.S. Fish and Wildlife Service and a wide array of experts from around the world to determine what is causing this condition,” he said.

The FWC is now testing the cats for toxins, including rat poison, along with possible infectious diseases and nutritional deficiencies.

The agency asked local residents to share personal surveillance footage that shows the animals having trouble with their legs.

Florida panthers, which are native to the state, are an endangered species, with approximately 120 to 230 adult panthers in the population.