Heidi McClain, DVM, Diplomate ACVIM SAGE Redwood City

With the wet weather returning (thank goodness), SAGE wanted to remind our clients about the potential of poisonous mushrooms popping up in your yard or at your neighborhood park. Poisonous mushrooms are an uncommon cause of liver failure in many parts of the country, but are one of the major causes of acute liver failure in dogs in our Redwood City practice. Amanita mushrooms are common in Northern California. Clinical signs of their ingestion include vomiting, abdominal pain, lethargy, bleeding, jaundice, and death. Initial signs of illness usually occur within 6 to 12 hours of the pet eating the mushroom. The ingestion of just one mushroom can cause death in an otherwise healthy 50 lb. dog.

If a mushroom is ingested, vomiting should be induced immediately. If the patient is already sick when presented, aggressive liver support must be provided with IV fluids, antibiotics, milk thistle, Vitamin E, and potentially other products such as antioxidants and blood products. Milk thistle has been used for centuries in patients with liver disease and seems to protect the liver if given in high doses very soon after ingestion of the mushroom. The prognosis depends on the amount of poison ingested, the extent of liver damage, and the administration of early and aggressive medical care.

At SAGE Veterinary Centers, testing for the amanita toxin can be performed on the bile or urine of a patient and submitted to the UC Davis toxicology laboratory. Mushroom identification can be performed at Oregon State University Veterinary School. (This does not mean that aggressive therapy can be postponed until the final test results are known, however.) In our Redwood City practice, we have seen mushroom toxicity patients from Burlingame to Portola Valley. The mushroom seems particularly prevalent on the Peninsula and in the general Bay Area.

This is a big deal. I actually run out to my front yard every morning to look for mushrooms popping up in the mulch. They seem to come out of nowhere every night. I felt so terrible for one of my clients last summer when she said, “I am a smart woman. How did I not know that I had something growing in my backyard that would kill my dog?” Most people are likely unaware that mushrooms in a yard or park can be so dangerous, so we want to help spread the word.

One of our veterinary nurses put together a few pictures of some of the common poisonous mushrooms in the Bay Area. This is not meant to be an exhaustive list. If you have a question regarding a specific mushroom, you may want to contact the North American Mycological Association.

There are four different groups of mushrooms in the SF Bay Area that contain alpha-amanitin that may cause liver failure.


Clockwise from top left: Amanita phalloides are associated with trees and are typically found near oak trees. Lepiota are small, with a pink-brown scaly cap. These can grow in lawns and in the forest, and are not associated with trees. Galerina autumnalis is a brown-spored mushroom that grows on branches and woodchips. Pholiota is a group of mushrooms that are brown-spored, grow in soil, and have a flat to conical cap.

Photo credits: Wikimedia Commons
Amanita phalloides, Archenzo, CC-BY-SA-3.0
Lepiota Mushrooms, Eridge Park, Andrew Howey, CC-BY-SA-2.0
Galerina marginata, Strobilomyces, CC-BY-SA-3.0
Pholiota aurivella, John Carl Jacobs, CC-BY-SA 3.0