Deadly Mushroom Poisoning Incident – April 2024

Below is a thorough email sent to clients in April of 2024, recounting a deadly and tragic mushroom poisoning incident.

Highly Toxic Amanita Mushroom

Hi Daniel,
This email is to bring to clients’ attention a very serious situation that recently started after the Thursday hike on March 28.
Extremely sadly, and unprecedented in the 13 years I’ve been hiking – my brother’s dog fell sick on Friday, March 29, after hiking the day before. This led to multiple vet visits with inaccurate diagnoses and treatment, and ultimately Rex passing away in the hospital on Tuesday morning, April 2, from liver toxicity that led to liver failure. This is an unprecedented and extremely sad situation, and something that could have been prevented with an early and accurate diagnosis and treatment.
To give you the most valuable information upfront – the veterinarian and I came to the conclusion on Friday that it’s very possible that Rex ingested poisonous mushrooms on the hike, but was treated for an upset stomach instead. I’m going to share the story below, as well as what I will be doing to prevent this from happening again, and signs to be aware of, as well as what can be done at the veterinarian or animal hospital.
The story/timeline:
On Thursday, March 28, my brother’s dog, Rex, came on the hike. Everything was fine that night, and he ate dinner. The following morning, he had bloody diarrhea, was vomiting, and having trouble standing. He was drinking, but would not eat anything, even high value foods. My brother took him to the vet on Friday, and they believed it to be an upset stomach, gave him fluids, and sent him home with antibiotics.
On Saturday, my brother took Rex back to the vet and they sent him home with more antibiotics.
Rex did not get better, and on Tuesday morning he was taken to the VCA on Sepulveda, Where he was put on fluids, and ultimately passed away later that morning due to liver failure. I found out about this late Tuesday morning, while heading up to the hike. Because the veterinarians had originally thought it was an upset stomach, I was not aware that it was anything more until hearing the final news on Tuesday.
The veterinarian suspected leptospirosis, so on the hike on Tuesday, I took Betadine to sanitize the only two small areas of standing water I know of that the dogs sometimes investigate. After the hike, I sanitized the entire van with about a gallon of rubbing alcohol. I had an email ready to send out on Wednesday with all of the information, and I was awaiting the leptospirosis test results. But, the test for leptospirosis came back negative on Wednesday, so I put the email on hold until I could piece together what had happened.
The only other thing that the veterinarian thought it may have been was that Rex having ingested a sago palm tree, which is highly toxic to dogs. But, sago palm trees are not indigenous to our area, and there are none that I know of on the land that we hike on, so that seemed unlikely.
I wasn’t able to get a hold of the veterinarian until Friday, and we both came to the conclusion that it may have been mushroom poisoning. She said that they did not have a test for mushroom poisoning, but could only figure that out through a process of elimination – by testing for anything else it could have been, and ruling those things out first. So, we are not 100% certain, but it seems very likely that was the case. I’m going to leave a lot of information below, as I would like to prevent this from ever happening again. Mushrooms were something I have seen occasionally on the hikes, but never realized were a deadly threat.
Mushroom information:
I have found out that there is a category of mushrooms that are toxic to the liver, with one species being especially toxic to dogs and humans: amanita mushrooms, nicknamed the death angel. I did not know it at the time, but I believe I have seen the white strain of these occasionally on the hikes. I will leave an expert from the VCA hospital’s website below, which sounds exactly like the course of events that took place with Rex. I will leave several website links at the bottom of this email.
“Hepatotoxic. These mushrooms affect the liver. With names like death cap or death angel, Amanitamushrooms sound really ominous and they are! Amanitamushroomscause liver failure that can be deadly. Owners may see their dog or cat nibble this type of mushroom, but do not become concerned because their pet looks fine immediately afterwards. Then 6-24 hours later, GI symptoms start to occur. Some pets appear to get better for a while giving owners a false sense of security; however, the underlying liver failure continues to progress. The pet becomes jaundiced, weak, lethargic, and sometimes comatose. What starts as mild GI upset quickly progresses to full blown liver failure that can result in death in a matter of days. If not treated quickly and aggressively, the liver failure is irreversible.”
In the 13 years I’ve been running the hikes, I have never had, or seen a dog become ill from eating mushrooms, and this was not on my radar. (Though, in January of this year, I did for the first time here of a dog from the pack eating mushrooms at her home and becoming sick. She was treated quickly and effectively, and had different symptoms. I was not aware from this incident what a serious threat they could be, and that this was something to watch out for on the hikes as well.)
Going forward:
What I’m going to do: I am now going to be on the hunt for any and all mushrooms we come across, (they are not common, but I have seen them). I plan to pick them up and bag them as if they were dog poop. I think this will drastically decrease the likelihood of a dog ingesting mushrooms on the hike. Mushrooms grow when they have a moist substrate, and so it seems that they will be most prevalent during the rainy season, and just after.
What clients can be aware of and do: I think it’s extremely important that all clients be aware of this information. The symptoms for Amanita mushroom poisoning include vomiting, diarrhea, tremors, seizures, and/or unwillingness to eat or drink. If your dog ever experiences these symptoms, especially 6-12 hours after a hike, please consider immediately taking him/her to the vet. Early treatment, which may include plasma transfusions, and IV fluids, seems imperative. It’s also important to get a liver panel immediately, and monitor it very closely for signs of liver toxicity developing or worsening. Please do not ever hesitate to reach out, and I will do my best to answer any questions quickly.
Pet insurance: It’s my opinion that pet insurance seems like a better option than ever before. I’ve seen the cost of veterinary care rise sharply in the recent years, and events like these are when it could really help. The total cost of Rex’s vet bills I believe were close to $6000. This is not something I usually cover, though it’s very possible I would help out in some way, as I will with Rex. I will leave two links to veterinary insurance companies that I have heard good things about directly below.
In conclusion:
There are certain unavoidable risks on the hikes, such as ticks, foxtails, and rattlesnakes, with some being more serious than others. I thought I had almost all of these on my radar, but I am now aware that mushrooms are a very very serious risk to keep clients and myself cognizant of. It’s my goal to make this the last time a dog ever passes away, or hopefully ever becomes hospitalized from ingesting mushrooms on a hike.
Thank you so much for your trust, and I will do my best to minimize any and all threats to any dog’s safety in my care. Please excuse the delay this email—the vet and I came to the conclusion that it may very likely be mushroom poisoning on Friday, April 5, and I wanted to take time to write a thorough email.
Please feel free to let me know if you do not feel comfortable sending your dog on any hikes for any reason, and that is absolutely no problem. Hopefully this will be the last time something like this ever happens.
Helpful links:

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