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Dogs please note: some walnuts and fungi can be poisonous

By Gary Bogue
Thursday, April 3rd, 2008 at 7:18 am in dogs, Fungi, Walnut poisoning.

San Francisco Bay Area dog owners please pay special attention. Wet husks from walnuts that fell from trees last fall can be poisonous to your dog.

Walnut poisoning seems to be a local phenomenon, occurring in Contra Costa County, parts of Alameda County and a few other areas around the San Francisco Bay Area.

If you or your neighbors have walnut trees — or there are fox squirrels around — carefully check out your yard and pick up any old walnuts you find. (If you don’t have walnut trees, squirrels can still bury nuts in your yard.)

Rotting husks sometimes contain an aflatoxin that can kill dogs that chew on them. Aflatoxins are poisons produced by mold, fungus and mildew.

Dogs like the bitter taste of old walnuts and husks and often gnaw on them. If the poisonous toxin is present, your pet may start shaking, twitching, acting jittery, disoriented and wide-eyed. It can also have violent seizures. If your dog has any of these symptoms, call your veterinarian for advice and get your pet in for treatment immediately.

And while we’re on the subject of things your dog might chew on:

Wild mushrooms, aka fungi and toadstools, grow in most yards during the winter rainy season and spring. The majority aren’t poisonous, but a few are, and you have no way of knowing which is which. Dogs (especially puppies) like the murky taste of some fungi, and will chew on them. As I said, most are harmless, but if your dog starts convulsing, vomiting or having severe diarrhea, call your vet immediately for advice.

One way to solve this potential problem is to check around the yard before letting the dog out in the morning and toss any fungi you find into the garbage. /Gary

“Sad Dog” picture by Flickr user used under Creative Commons license

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8 Responses to “Dogs please note: some walnuts and fungi can be poisonous”

  1. mark Says:

    is there a cure for this walnut poisining in dogs>>???

  2. Gary Says:

    Dogs can be treated by pumping their stomachs if you get them in soon enough, and by treating the symptoms. A lot of it depends on how soon you can get the dog in for treatment. /Gary

  3. Courtney Says:

    I just recently moved to San Jose. My lab started shaking and pretty much all the symptoms you listed above. I looked and saw that she had swallowed part of a walnut. It was green/moldy on the inside. I instantly took her to the vet. They made her throw up and are keeping her for observation. I hope she will be ok.

  4. Ron Odom Says:

    Can a dog get poisoned by packaged walnut meats. Mine (Border Collie) ate a bunch that were thrown out and the next day had violent siezures. He also loves to eat rotting/decayed Chinese Chestnuts which are all over my yard. Any advise/comments?

  5. Gary Bogue Says:

    I don’t know about the packaged walnut meats. I’ve never come across that before. I wonder if the rotting Chinese chestnuts have developed some sort of fungus similar to the walnut husks? The fact that your dog had violent seizures might indicate that. I’d definitely clean up all those rotting chestnuts from your yard, or certainly keep your dog out of that area so this doesn’t happen again. It might not recover next time. /Gary

  6. Natalie Timm Says:

    I’m wondering about walnuts in dog biscuits, for holiday baking. And, can you help me with this?—-what about the tree in our back yard, an aging camphor? The berries and leaves from this messy evergreen fall into water bowls and into a small 4 foot diameter pond. Our dog drinks from these sources–is it a contaminant/poison and would it be concentrated because there’s no circulation of water? I couldn’t find info on camphor tea. Thank you so much. We all worry about our environment for ourselves and our pets. Best regards, Natalie

  7. Gary Bogue Says:

    Natalie: Walnuts used in baking are not a problem.
    I went to and did a search for … camphor tree, toxic plant … and found that it is considered a toxic plant for pets. So you should make sure to put your dog’s water dish where the berries and leaves can’t fall into it. I don’t know what you can do about keeping stuff from falling into your little pond. You’ll have to figure that out. You should Google the above subject on your own and learn more about the camphor tree. How long has your dog been with you and drinking from the pond and water dish? Maybe it’s not a big problem? or maybe it is. It might be a good idea to have a chat with your veterinarian about it. Hope this helps. This is one file I found that lists camphor trees as toxic to pets:

  8. susan Says:

    Hi,My dog spent the weekend at the veterinary emergency hospital because she was extremely dehydrated from vomiting, had very low plasma albumen, and had extremly elevated liver enzymes. These symptoms indicated mushroom poisoning. However, since my yard consists of elevated porches with no fungus and because she had not been walked for 4 days, I believe it is more likely that she was poisoned by aflatoxin from chewing on acorns. There was evidence that she had chewed on acorns and examination of lots of acorns has convinced me that they are all filled with mold. My internet research indicates that this mold is most likely always Aspergillus flavus and that it would only take one contaminated acorn to cause these symptoms in my 20 pound dog. Had I not rushed her to the emergency hospital, she would have died. Please post this comment to alert other Bay Area dog owners to this potential source of aflatoxin. Thanks,Sue

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