TailVilleWhy
Black walnuts are toxic to dogs, and any walnut that goes moldy can harbor tremorgenic mycotoxins that cause tremors and seizures, often without visible signs. Walnuts are also large and hard enough to block a small dog's throat or intestines, and their high fat content raises pancreatitis risk. Data on cats is limited, but the same reasons apply.
How to give it / if eaten
If your pet ate several walnuts, or old, moldy or fallen ones, contact your vet or an emergency clinic right away with the amount and time. Don't induce vomiting at home without a vet's instruction.
Watch for these signs
Vomiting, diarrhea and poor appetite are common. Mold toxins can cause tremors, wobbling, high temperature and seizures within hours, and a blockage brings repeated vomiting and no stool.
FAQ
My dog ate one walnut. Is that a problem?
One fresh walnut usually isn't a big deal, but it could have been moldy and can be a choking hazard. Go to a vet at once if you see tremors or vomiting.
What about walnut cakes (hodu-gwaja)?
They're full of sugar, flour and sweet bean paste on top of the walnuts, so they're not a suitable treat.
General information only. Weight, age and health conditions change how a pet reacts, so ask your vet if you are worried.