Mushroom Poisoning in Dogs
Since moving here to the UP we are discovering the large variety of mushrooms that can grow in a yard. We've even had some that were basket ball sized and white and others that look like a "classic" mushroom - poisonous or not? I'm not really sure but we obviously now live where there is an abundance of fungus.
So my mission was to find out what if they eat that stuff????? Occasionally dogs will eat mushrooms in yards and while on walks, though surprisingly, mine never have. The dogs didn't have much interest at our old house, there was one kind and it never interested anyone or made anyone sick, so I didn't worry about it. However, while 99% of mushrooms have little or no toxicity, you still have to worry about the 1% that are highly toxic can be life-threatening. Since moving to the UP, there are mushrooms of all kinds everywhere so I thought I better get more intelligent on the subject. Better to be safe than sorry - and learn to identify the ones that tend to grow in your yard. 
If you suspect that your Malamute has consumed a poisonous mushroom, contact your veterinarian, Malamute emergency hospital, or the animal poison control center (note: there is a fee for using this service). First thing to do is get help for the dog, then identify the mushroom so you know what you are dealing with. Different mushrooms affect different organs. NAMA provides a list of volunteers who are able to assist with identification in poisoning cases. Since most people are not familiar with mushroom identification, get assistance - this is not something to guess at from a book.
Many mushrooms have a fishy odor so attract dogs. Some have the toxins ibotenic acid and muscimol which are not lethal to humans but can cause death in dogs. If a dog or cat has consumed Amanita muscaria or Amanita pantherina, the giving the dog atropine can intensify a coma-like sleep, greatly increasingly possibility of death. With these toxins the dogs typically go into a deep coma-like sleep a few hours after eating, fall asleep and recovery is generally complete about 6 hours (but as long as 72 hours) later. Sometimes the decision to euthanize is made with dogs because it appears they will not recover - but in most cases the dog DOES recover so it's best to wait on any euthanization if the dog appears to be in a deep coma.
There are many different types of mycotoxins. 14 distinctive types of mushroom poisoning is found worldwide, and about 10 distinctive patterns of reactions to mycotoxins have been observed in North America. However, since most mushroom species are rarely eaten, many toxins are poorly documented. There is a great deal of confusion concerning these toxins, and much misinformation about their treatment. Atropine is NOT indicated in cases of poisoning by ibotenic acid or muscimol but is frequently cited as a treatment in medical literature so your vet may not even have the right information about treating. That's why it's important to contact an animal poison control center and positively identify what he ate.
There are so many kinds of mushrooms that it would be impossible to list them here. Below are a few that are toxic so you'll definitely want to remove these from your yard! Many dogs die each year from consuming mushrooms containing amatoxins. The symptoms are characterized by a 6-12+ hour delay in symptoms then severe GI distress and refusal to eat or drink. In one recent California case, a dog was saved by aggressive rehydration therapy plus needle aspiration of the bile from the gall bladder (contact www.Malamutesreferralcenter.com or phone 510-219-0112 for more information if you have a dog that you suspect has mushroom poisoning). Depending on the mushroom's toxin - it can cause liver, kidney, and even brain damage so it's important to get the correct support therapy from your vet.
Common symptoms to watch for:
- Nausea
- Drooling
- Vomiting
- Diarrhea
- Abdominal pain
- Walking drunk
- Depression
- Tremors
- Seizures
- Organ failure (liver & kidney)
There are several thousand species of mushrooms located throughout the United States, but only a small percentage is poisonous. Mushroom identification is difficult, so should only be done by experts called mycologists. The majority of mushroom deaths in Malamutes are from Amanita, Galerina, and Lepiota. Depending on the type/species of mushroom eaten, several organ systems can be affected: hallucinogenic (e.g., visual disturbances), gastrointestinal (e.g., vomiting, diarrhea), central nervous system (e.g., ataxia, tremors, seizures, death), liver failure (e.g., vomiting, black-tarry stool, increased liver function blood tests, etc.), kidney failure failure (e.g., halitosis, anorexia, vomiting, inappropriate thirst or urination), etc.
If you see your dog eat a mushroom, contact your veterinarian or Malamute Poison Helpline immediately for treatment advice.
More information & Helpful links...
Mushrooms in North America Photos at https://namyco.org/toxicology/poison_syndromes.html