By Dave Onorato, Lara Cusack, and Mark Cunningham
Florida’s panther has made significant progress towards recovery during the last 25 years. One aspect of our research that has assisted with this improved outlook for panthers is our continual monitoring for signs of any disease issues that may surface in the population, since these have the potential to impact prospects for long term persistence. During this period, a number of significant disease events have occurred, including infections with feline leukemia virus and pseudorabies virus. In spring 2018, via a collaboration with members of the public and Corkscrew Swamp Sanctuary (CSS) in Collier County, the FWC Panther Team identified a litter of kittens on trail camera videos that appeared to have weakness in their hind limbs. Subsequent deployment of additional video cameras in the area by FWC further documented the difficulties one of these kittens was having when trying to keep up with the dam.
This neuromuscular disorder (termed feline leukomyelopathy [FLM]) has now been documented via necropsies in two panthers and a bobcat. While the total number of panthers impacted is unknown, we have evidence that <10 are affected. FLM presents as demyelination of portions of the spinal cord, brainstem, and cerebellum. It is suspected that this impacts locomotion in the afflicted animals. Since the initial documentation in 2018, FWC has ramped up monitoring and capture efforts in areas where we suspect FLM is affecting wild felids. Documented cases have so far been restricted to Collier County, although video and photos suggest FLM may be present in other counties in SW Florida. There are still many unknowns as to what might be the root cause of FLM; is it viral? congenital? is it related to the application of herbicides or pesticides? Analyses on samples we have collected from afflicted felids have permitted us to determine that FLM is probably not congenital, as it has been documented in two species. A viral component has not been ruled out. Of particular interest is the plausibility of an environmental toxicant. Since we’ve seen most cases of FLM present themselves in panther kittens, it seems reasonable that a toxicant may be more impactful on kittens as opposed to adults. One thing is certain; demyelination resulting from FLM is permanent, so afflicted animals can’t recover.
The outpouring of public support has been amazing with regards to sharing videos and reports of animals appearing to have the same condition in Florida and beyond. Furthermore, FWC has received offers of assistance from experts in veterinary medicine from around the globe in order to try and determine what is causing FLM. Our long-term research and monitoring program has permitted us to identify this condition in a timely manner, something that could prove critical if FLM ends up being more widespread in Florida panthers.