Following a health scare last fall, it was presumed that Sadie, a 10-year-old black Labrador retriever, had eaten Amanita phalloides fungus growing in her family’s yard. 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.

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

The next day, the family traveled to Lake Tahoe where Sadie was not acting like herself late that night and wouldn’t eat the next morning. Shortly thereafter, when Sadie was too weak to climb stairs, Gardner and her husband sought veterinary care at the nearest clinic. There, it was discovered that Sadie’s liver values were elevated following a blood test, and the veterinarian helped the Gardners with an immediate emergency referral to the UC Davis veterinary hospital.

Upon arriving at UC Davis, Sadie became so weak that she couldn’t walk. Testing revealed Amanita poisoning and consequent severe liver failure – that she had indeed eaten a death cap mushroom. After discussing Sadie’s guarded prognosis with the care team, the Gardners elected to hospitalize her with supportive care of fluids and antibiotics, with the potential to move on to more advanced interventions if her condition warranted.

The Gardners and their daughter Stacie Casella visited Sadie every day while she was hospitalized, even bringing Sadie’s sister to visit once.

“After seeing her sister, Sadie’s tail wagged like it hadn’t ever wagged before,” said Casella. “We feel that those visits may have given her a will to live.”

Sadie’s liver function improved throughout the week, and she was discharged after 10 days.

The Gardners had hoped that her troubles were behind her, but soon after, Sadie lost her appetite and was vomiting. So, they returned to UC Davis.

After further testing, Sadie was diagnosed with Addison’s disease, possibly associated with, and brought on by the mushroom poisoning. Addison’s disease, also known as hypoadrenocorticism, is a condition that results in a lack of critical hormones, which are needed to maintain health. (In 2020, UC Davis veterinary scientists developed an artificial intelligence program to detect Addison’s disease.)

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

To help veterinarians prepare pet owners to understand the implications and long-term consequences of this intoxication, Dr. Dear, along with DVM student Emily Cohen and resident Dr. Courtney Moeller, recently published a study on Sadie’s case. This clearer understanding of post-intoxication outcomes was published in the journal Veterinary Sciences. The case report is the first to describe the chronological association between mushroom poisoning and the subsequent development of Addison’s disease in a dog.

If untreated, Addison’s can have drastic consequences, but if it is caught early and treated appropriately, the prognosis is excellent. Fortunately, Sadie's Addison's disease was diagnosed when she was relatively stable, and she responded well to treatments. She will need to be on lifelong medications to supplement the critical hormones her body is not making, but if well-managed, they won't impact her quality of life.

Now nine months after Sadie’s poisoning, she is doing great and being well managed for her Addison’s disease.

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Death cap mushrooms are prevalent in the summer and autumn. Pet owners are encouraged to be diligent about clearing their yards of them, as well as being keenly aware of their presence on walks. Learn more about mushroom toxicity in UC Davis’ Animal Health Topics database.