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Canine death cap mushroom poisoning causes unreported consequence


After beating an 80% chance of death, Sadie, her family, and UC Davis veterinarians discovered the poisoning led to Addison’s disease diagnosis

 Sadie (Image courtesy of UC Davis School of Veterinary Medicine)

Sadie (Image courtesy of UC Davis School of Veterinary Medicine)

Sadie, a 10-year-old Labrador retriever, and her owners, Eleanor Gardner, her husband, and daughter Stacie Casella, took a trip to Lake Tahoe last year and upon arrival, the family noticed Sadie was not acting like herself. The next morning, the family said Sadie was not eating and appeared to be too weak to climb the stairs. The Gardners then found a clinic nearby and brought Sadie in to be examined. Here, the veterinary team performed a blood test that showed her liver values were elevated and the team gave her an immediate emergency referral to the UC Davis Veterinary Hospital.

When the family arrived at UC Davis, Sadie’s condition worsened, and she could not walk. According to the release, further testing performed at UC Davis revealed that Sadie was suffering from Amanita poisoning from ingesting Amanita phalloides fungus, commonly referred to as death cap mushrooms, that Sadie most likely found in the family backyard.

“We didn’t even notice [the mushrooms] were growing,” said owner Eleanor Gardner in the release.1 “We do now, though. Not one goes by that we don’t pick up right away.”

Death cap mushrooms are extremely poisonous and can cause almost immediate liver and kidney damage and have a 20% survival rate for dogs.1 They are large mushrooms with a broad, off-white cap and can grow several inches tall. They tend to grow in warm and moist conditions in the late summer and fall.2 A human ingesting a single mushroom can be fatal and because pets have a small body weight, a smaller quantity dose can be lethal.

The veterinarian team and Sadie’s family reviewed the prognosis, and the family decided to hospitalize her with supportive care of antibiotics and fluids with the possibility of moving on to a more advanced intervention if warranted. The Gardner family returned to UC Davis every day to visit her, even bringing her sister to visit once. During her stay, her liver function improved and she was eventually discharged 10 days later.

Although they were happy to have her home, the family soon realized Sadie’s health issues were not behind her. The family would soon return to UC Davis because Sadie lost her appetite and was vomiting. The veterinary team performed more tests and Sadie was diagnosed with Addison’s disease, which is possibly associated with or brought on by the death mushroom cap poisoning.

“The development of Addison’s disease following Amanita poisoning is an unreported consequence of disease,” explained Jonathan Dear, DVM, MAS, DACVIN, co-chief of the Internal Medicine Service that managed Sadie’s care.1

To help veterinary professionals better prepare and help clients understand the implications and possible long-term consequences of intoxications like this, Jonathan Dear, DVM, MAS Emily Cohen, DVM candidate, and Courtney Moeller, DVM, published a study based on Sadie’s case. The study, published in Veterinary Sciences,3 paints a clearer picture of intoxication outcomes and is the first study to describe the chronological association between the development of Addison’s Disease and mushroom poisoning in a dog. 

Sadie’s diagnosis came when she was relatively stable and responded well to treatment. Nine months later, Sadie continues to do great with her disease being well managed.


  1. Mushroom Poisoning Has Unreported Consequence for Dog. News release. UC Davis College of Veterinary Medicine. September 29, 2023. Accessed September, 29, 2023. https://www.vetmed.ucdavis.edu/news/mushroom-poisoning-has-unreported-consequence-dog
  2. Death cap’ mushrooms pose threat to dogs. University of Wisconsin-Madison School of Veterinary Medicine. Published July 13, 2022. Accessed September 29, 2023. https://www.vetmed.wisc.edu/death-cap-mushrooms-pose-threat-to-dogs/
  3. Cohen EA, Moeller CM, Dear JD. Hypoadrenocorticism in a Dog Following Recovery from Alpha-Amanitin Intoxication. Veterinary Sciences. 2023; 10(8):500. https://doi.org/10.3390/vetsci10080500
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