Elk Sickened by Lichen Examined

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While a lichen called Parmelia has been fingered as the probable cause of more than 300 elk deaths near Rawlins, investigators say more work needs to be done in the coming months to define how and why it caused such a large and sudden die-off.

Within a week of being fed a diet of lichen by Wyoming Game and Fish Department veterinarians, several elk developed signs of illness similar to those seen in the original episode. An affected elk was examined post-mortem Monday at the Wyoming State Veterinary Laboratory (WSVL) at the University of Wyoming, and diagnosticians there will test tissues from more elk on the lichen diet to identify the basis for clinical illness.

Parmelia grows in bare soils in much of Wyoming. Until now it has not been considered toxic for elk, and some wildlife biologists consider it valuable winter feed. However, the lichen apparently produces an acid that appears to be toxic, according to Walt Cook, a veterinarian with game and fish.

“There’s a lot that we don’t know about the lichen,” said Cook. “We don’t know if Parmelia from this area concentrated unusually high levels of acid this year due to drought. Also, we don’t know if these elk were simply not used to eating lichen and therefore couldn’t handle it. There are a lot of questions ahead.”

Toxicologist Merl Raisbeck of the WSVL and the Department of Veterinary Sciences noted that “there is some old literature indicating that under unusual circumstances lichen is poisonous.” Raisbeck is working with Cook and Terry Kreeger, the supervisor of wildlife veterinary services, on an experimental study using elk to define the toxic principle that is involved and why it makes animals ill.

The first of several elk on the experimental lichen diet was examined Monday by veterinary pathologists Professor Beth Williams and Assistant Professor Todd Cornish of the WSVL. Some of the changes found in the carcass were consistent with what was seen in the original die-off. “So far, so good,” said Williams, “but we still need to do a lot more work to lock this in.”

Raisbeck commented that given the scale of the die-off and limited knowledge about lichen poisoning, conducting further research would be an excellent project for a graduate student interested in toxicology. Raisbeck plans to work with game and fish biologists and UW students to collect large quantities of lichen from the affected area in southeastern Wyoming.

Scientists in the game and fish department tapped a wide range of scientific talent in Wyoming, including investigators at UW, to help identify the cause of the massive number of elk deaths. Those consulted were Ed Schmidtman of the USDA Arthropod- Borne Animal Disease Research Laboratory (ABADRL), state veterinarian Jim Logan, JayDee Fox, Associate Professor Warrie Means of the Department of Animal Science, Dr. Reed Shafer of Cheyenne, Terry Creekmore of the Wyoming Department of Health, personnel with USDA-APHIS and the Department of Homeland Security, and wildlife veterinarians and biologists across the country.