Mushroom Toxicity in Dogs: What to Know

Mushrooms. It’s likely you’re worried about your dog or family members consuming them as you’ve heard old wives tales about how poisonous they can be or because of their hallucinatory effects. But are the stories true?

Well, as most tales are, it’s complicated! Partly true and partly legend, and much of the “it depends” answer lies in which particular type of mushroom is in question, as there are hundreds of different mushroom varieties, and not all of them are toxic to dogs.

In this post, we’re going to cover mushroom toxicity in dogs to tell you which species cause problems, what signs and symptoms to watch out for if your dog has eaten some of those bad mushrooms, and what to do if your dog has indeed become ill as the result of ingesting mushrooms.

Which Mushrooms are Poisonous to Dogs?

Thankfully, we can tell you first that a very low percentage of mushrooms are actually toxic to dogs. This is a relief given how often you see mushrooms in your yard, in the neighborhood, the dog park, or out on hikes. And especially since your dog seems so fond of getting into them!

According to the American Kennel Club, only about 50 to 100 species of mushrooms are known to be toxic out of roughly 10,000 recognized species worldwide.

While health food nuts continue to scour the country for edible mushrooms, dog owners must be on the lookout for the toxic varieties to keep their dogs from getting ill.

The tricky thing about determining which are toxic and which are harmless is that it is essentially a guessing game unless you know for sure what type you are dealing with. Mushrooms can be very difficult to properly identify, and those that are harmful can range in toxicity from nearly harmless to deadly.

Mushrooms typically grow in the spring or fall when things are wet and still relatively warm. To help you sort through the mushroom masses, it can be easier to think of them in terms of a few categories, including hepatoxic, neurotoxic, gastrointestinal, and nephrotoxic.

Hepatoxic Mushrooms

The most common class of mushrooms to see involved in dog poisonings in North America are the Amanita species. Hepatoxic means that these mushrooms are toxic to the liver.

These mushrooms are well known by their common names, such as death cap or death angel (Amanita phalloides), angel of death (Amanita ocreata), false parasol (lepiota), panther cap (Amanita pantherina), and fly agaric (Amanita muscaria), which suggest their respective potencies. The Galerina species is another common species involved in dog poisonings.

The Amanita mushrooms cause acute liver failure in dogs, which can set in rather quickly. These mushrooms are deceptive, however, as the onset of symptoms is often delayed six to 12 hours, which may give the owner a false sense that everything is okay with their pup. Flash forward to the next six to 12 hours and their dog may show signs of gastrointestinal distress which can quickly move to liver failure and death within as little as a day in the most severe cases.

The Amanita mushrooms are found throughout North America and are especially common in the Pacific Northwest, as well as parts of California and the northeastern U.S.  

Neurotoxic Mushrooms

There are three main groups of mushrooms that cause neurological symptoms, including psilocybin, also known as “magic” mushrooms, hydrazines, and isoxazole mushrooms. The onset of symptoms with this class of mushrooms sets in much more rapidly in as little as 30 to 90 minutes, and typically carry out their course in six hours.

Psilocybin mushroom exposure occurs more often inside an owner’s home than outdoors, as the dog typically is able to get into their owner’s supply. Owners must take great care to keep their mushrooms in a safe place where their dog cannot access them, as the psychotropic effects of the mushrooms can be very frightening to a dog.

With hydrazine mushrooms, gyromitrin is the compound that creates neurological symptoms. These signs may include dog weakness, tremors, and canine seizures, gastrointestinal issues, ataxia, and more. Hydrazine mushrooms can even lead to hemolysis and methemoglobinemia, even going as cause to cause renal and hepatic issues.


Like hydrazine mushrooms, isoxazole mushrooms can cause ataxia, gastrointestinal issues, hallucinations, disorientation, vocalization, alternating between canine lethargy and agitation, and even tremors and seizures.

Gastrointestinal Mushrooms

There is a large group of mushrooms that tend to cause gastrointestinal issues in dogs, with symptoms that range from mild to more severe. The onset of signs with this group of mushrooms will also be rather rapid, setting in as quickly as within 15 minutes, and again, usually less than six hours after ingestions.

The muscarinic mushroom is one within the gastrointestinal group to be particularly wary of as it can cause significant canine diarrhea and vomiting in dogs that may lead to other issues.

Nephrotoxic Mushrooms

This is a rarer class of mushrooms that do not poison dogs but can be toxic to humans. They are typically found in Europe and the onset of symptoms will be delayed, but again, they do not yet appear to pose harm to dogs.

The types of mushrooms that are in your neck of the woods will vary widely based in where you live in the continental U.S. It is best to check with local experts and your veterinarian to help you identify any mushrooms found in your area to see whether or not they are toxic.

What Causes Mushroom Poisoning in Dogs?

Mushroom toxicity, or mushroom poisoning, occurs when a dog ingests one of the toxic varieties of mushrooms outlined above. The severity of the dog’s poisoning will depend on a number of factors, including the individual dog’s size and health history, but mainly the type of mushroom the dog eats and how much of it the dog consumes.

This can be a hazard for dogs strictly based on the average amount of time that they spend outdoors. It’s nearly impossible to keep track of their every movement, especially if they are ever allowed to roam freely. It’s best to pay attention to anything your dog is able to get a hold of, and if you notice it eating a mushroom, the safest course of action is to assume that it is poisonous.

The vast majority of documented mushroom poisonings are caused by the Amanita species of mushroom. Specialists and veterinarians believe that dogs are attracted to these mushrooms because they have a fishy odor.

What chemically causes the poisoning within dogs is more complex to figure out as not all mushroom toxicity cases are reported on record and limited toxicology testing is available. What is known is that when your dog eats a poisonous mushroom the toxins spread throughout the dog’s system which can result in acute effects, which, depending on the type of mushroom and severity, can cause such severe effects as liver failure, coma, and death.

Aggressive veterinary intervention is needed to treat any mushroom toxicity in dogs. Don’t wait for symptoms to appear either, bring your dog in immediately and bring a sample of the mushroom you suspect your dog ingested if possible.

Symptoms of Mushroom Toxicity in Dogs

The symptoms of mushroom toxicity in dogs will vary greatly depending on the type of mushroom the dog ingests. The main thing to remember is that you should not wait for symptoms to appear before you seek help for your dog.