Mushroom Poisoning in Dogs: What PNW Pet Parents Need to Know
Peak mushroom season is back in the Pacific Northwest, bringing with it an increased risk of mushroom poisonings in dogs.
Although most cases of mushroom ingestion in dogs are harmless, especially following veterinary care, a few highly poisonous mushrooms can cause death.
The American Society for the Prevention of Cruelty to Animals (ASPCA) Animal Poison Control Center responded to almost 5,000 cases involving mushrooms in a recent 10-year period, 91.2% of which involved dogs, including 23 who died.
“Because mushrooms can be so toxic, it’s important to immediately bring your dog to a vet right away for decontamination (inducing vomiting and giving activated charcoal to bind up any poison),” per The Oregon Veterinary Medical Association. “Sometimes stomach pumping (i.e., gastric lavage) is even necessary in severe cases.”
Learning about plants in the PNW toxic to pets, including amatoxin-containing mushrooms like death cap mushrooms, can go a long way in keeping our companion animals safe and healthy.
Amatoxin-Containing Mushrooms in the PNW
Mushrooms that contain amatoxins are responsible for the majority of fatal mushroom poisonings in pets, according to the Pet Poison Helpline. These include the Amanita, Galerina, and Lepiota genres.
In the Pacific Northwest, distinct species of these mushrooms to watch out for include Amanita pantherina, Amanita phalloides, and Amanita aprica. According to Northshore Veterinary Hospital in Bellingham, A. pantherina is one of the most common culprits of mushroom poisonings in dogs in our area.
Eating just part of one of these amatoxin-containing mushrooms can be fatal in dogs: A single A. phalloides mushroom cap, for example, can contain about six times the lethal dose of alpha-amanitin for an 11-pound dog (i.e., 15 mg, with the estimated oral LD50 for methyl-alpha-amanitin in dogs at 0.5 mg/kg), according to the Journal of the American Veterinary Medical Association (JAVMA).
Dr. Michelle Dear, veterinarian at the UC Davis School of Veterinary Medicine, said of A. phalloides, “More commonly referred to as death cap mushrooms, they are extremely poisonous, causing liver and kidney damage almost immediately, and leading to death in 80% of dogs that eat them.”
Studies that support this include a case series of 59 dogs with alpha-amanitin poisoning, where only 13 of 50 treated dogs (26%) survived (JAVMA, March 2021).
If you suspect that your dog may have eaten mushrooms, seeking immediate poisoning and toxicity veterinary care is always recommended. A recent review of 421 cases where dogs ingested mushrooms found that 64.4% involved harmless mushrooms and dogs could recoup at home once the mushroom was identified, 64% of cases were managed at home, and 33% were hospitalized and treated, with an overall survival rate of 98.6% (Veterinary Medicine and Science, April 2023).
The Danger of Delayed Symptoms
There are certain signs to look for indicating that your dog has ingested mushrooms. Experts warn not to take a “wait and see” approach if you suspect mushroom poisoning.
The Pet Poison Helpline and the ASPCA list the following as symptoms of various types of mushroom poisoning in dogs:
- Vomiting
- Diarrhea
- Salivation
- Abdominal pain
- Hallucinations
- Tremors
- Seizures
- Vocalization
- Mydriasis (large pupils)
- Ataxia (lack of muscle coordination)
- Tachycardia (increased heart rate)
- Disorientation
- Hyperthermia
- Anxiety
These symptoms typically appear within three hours in the case of lower-risk mushrooms, or more than six hours later in the case of lethal mushrooms.
A delay in the appearance of symptoms not only tends to indicate life-threatening poisoning but can also cause a delay seeking care. In some cases, pet owners may no longer associate the dog’s activity, e.g., foraging in the backyard seven hours ago, with the symptoms they are now experiencing, and veterinary care may be skipped altogether.
“Do not wait until signs develop!” the Pet Poison Helpline warns. “Immediately contact your veterinarian or Pet Poison Helpline for further guidance.”
Calls to the Pet Poison Helpline for guidance come with an $89 incident fee that covers both the initial consultation and any follow-ups. The ASPCA Animal Poison Control Center lists a similar fee of $95 per case.
Peak Mushroom Growth Time
The review mentioned earlier of 421 cases of mushroom poisonings in dogs revealed that most occurred during the fall, which is when mushrooms fruit in temperate climates like that of the PNW (Frontiers in Veterinary Science, April 2023).
A more specific breakdown revealed that 29.9% of cases occurred in September, 20.4% in October, 17.6% in August, and 12.1% in July, with January and February each only accounting for .5%.
Looking to the 59-dog study, 47% occurred in the summer, 24% in the fall, 15% in the spring, and 14% in the winter, with over three-quarters (76%) of all cases occurring between May and October.
Wetter Weather & Increased Cases
Going back yet again to the 59-dog study, which spanned 14 years, the researchers found that a disproportionate 36% of cases occurred in 2014 alone, which they attributed to a spike in precipitation that year (JAVMA, March 2021). That is, mushrooms like to grow in warm, wet conditions.
The ASPCA also reports that mushroom growth is more common from spring to fall, when the weather is warm, wet, and rainy.
Local experts advise PNW pet parents to check their backyards for mushroom growth after thunderstorms and rainfall.
In Central Oregon, one vet clinic reported treating about a dozen dogs for mushroom poisoning in a recent season and had already seen three cases the following spring after particularly rainy conditions (The Bulletin via OSU Ask Extension, July 2020).
Fir & Other PNW Trees That Support Mushroom Growth
The same Amanita species that cause such a risk to our dogs also tend to like the trees that grow in our area, specifically fir, spruce, and madrona trees, especially common in Western Washington (Animal Emergency & Specialty, November 2016).
Puppies May Be at Greater Risk
Locals will also want to keep in mind that puppies may be both more susceptible to mushroom ingestion and more vulnerable to serious risks.
A Western Washington emergency veterinary hospital reported that most cases of mushroom poisoning it treats are in dogs less than one year of age.
Frontiers in Veterinary Science featured a recent case where a 12-week-old Shetland Sheepdog died after eating alpha-amanitin-containing mushrooms. The puppy had experienced vomiting and diarrhea that progressed to stupor and hypoglycemic shock.
Don’t Try to ID Mushrooms on Your Own
“Never pick and eat wild mushrooms unless they’ve been identified by a mushroom expert,” the Oregon Poison Center warns, specifically telling people to keep a close eye on kids and pets when outside.
Experts at the Pet Poison Helpline also warn against trying to identify mushrooms, because doing so is difficult even for people who are very familiar with them.
Seeking Emergency Care for Your Dog
If you suspect that your dog has eaten a mushroom, waiting for symptoms to appear or trying to identify what type of mushroom it was can delay critical care.
“A dog that consumes … mushrooms can go from healthy to very clinically sick, to dead within 24 to 48 hours,” says Dr. David Dorman, toxicology professor at North Carolina State University. “So it’s a very rapid disease syndrome.”
Animal Emergency & Speciality Center, a local provider of emergency vet services, reported that most patients it sees recover from mushroom poisoning within 12 to 24 hours after receiving treatment.
One specific recent local case in Washington involved a dog exposed to A. pantherina who was vomiting, unsteady, panting, and unable to walk. After being treated for two days with IV fluids, the dog recovered.
Other positive outcomes were reported by Journal of Veterinary Emergency and Critical Care, specifically five dogs who had been treated for amatoxin poisoning in 2024 using an adapted Santa Cruz protocol who all survived.
Follow-up appointments can also help ensure your dog’s long-term health. A recent case out of UC Davis showed that alpha-amanitin poisoning may lead to the later development of Addison’s disease in dogs (UC Davis School of Veterinary Medicine, September 2023).
A Note on Hallucinogenic Mushrooms
This article wouldn’t be complete without alerting readers to another mushroom-toxin threat for dogs: hallucinogenic mushrooms, or “shrooms.”
Notably, in 2024 the ASPCA reported a 74% increase in calls related to “magic mushrooms” between 2022 and 2023, with recreational drugs (including hallucinogenic mushrooms) remaining among the top 10 toxin categories for the third consecutive year.
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