Florida expert: Keep pets, livestock away from false parasol mushrooms

Published: May 2 2013

Category:Research

GAINESVILLE, Fla. — Dogs are notorious for eating just about anything, and the nastier, the better — which is why a University of Florida expert is advising canine owners to keep an eye out for poisonous mushrooms as summer approaches.

One particularly common species is known scientifically as Chlorophyllum molybdites and often called the false parasol, said mycologist Matthew E. Smith, an assistant professor with UF’s Institute of Food and Agricultural Sciences. The large, light-colored fungus grows in grassy areas such as lawns throughout the Eastern United States and in California.

“Mushrooms can grow very quickly, so it’s important to be observant,” Smith said. “If you have a puppy or a dog, you should check the yard before you let the dog out, or supervise it when it goes outside.”

Though poisoning cases are rare, the false parasol causes intense gastrointestinal distress in people and may be deadly to dogs and horses. Puppies and adult dogs that like to chew are especially at risk for ingesting the fungus.

The false parasol is easy to spot against a grassy background. White or tan, it has a domed or flat cap and a thick stem; at maturity it may be several inches tall. Colonies often grow in circles, called “fairy rings.”

Smith suggests that animal owners learn to identify the species, check their property often and destroy the mushrooms if they appear where animals might eat them.

When a veterinarian suspects mushroom poisoning, Smith is sometimes called upon to identify any fungus fragments that have been recovered.

It’s not an easy or pleasant task. But Smith said he’s glad when he can give owners helpful information. He’s been involved in 10 to 15 cases of suspected mushroom poisoning in dogs since arriving at UF about 18 months ago.

Photographs can aid identification, he said, especially if they show intact specimens and the area where the fungus grew.

False parasols are responsible for more human poisonings than any other U.S. mushroom species, but they are seldom cited in animal poisonings, said Michael Beug, a professor emeritus with The Evergreen State College in Olympia, Wash., and a noted mushroom expert.

Hard statistics on dog poisoning cases are kept by the North American Mycological Society, and their records from 1980 to the present include just three cases with the false parasol.

However, Beug noted that when he hears about a case of mushroom poisoning in an animal from Florida, it invariably involves the false parasol.

“C. molybdites can be pretty devastating,” Beug said. “Especially if it’s eaten raw, which is the way dogs eat them.”

There’s generally not much that veterinarians can do for afflicted dogs except provide intravenous fluids and palliative care to reduce distress and discomfort.

Fido isn’t the only animal potentially in danger: Livestock are at risk, too.

Grazing animals such as horses may consume wild mushrooms accidentally as they browse on grass and other forages. Horses suspected of consuming false parasols should receive immediate veterinary care.

Smith’s overall advice: Discourage dogs from investigating wild mushrooms.

“And don’t let your dog eat any mushrooms, even supermarket ones,” he said.

Credits

Writer
Tom Nordlie, tnordlie@ufl.edu
Contact
Matthew E. Smith, trufflesmith@ufl.edu

Category:Research