Thanx for the reminder.
One of my Dogs overdosed on Grapes, he went stiff as a board and looked like a stand up stuffed toy. Took hours at the Vet filling him up with infusions, trying to dilute the sugar. We put almost three quarts in him and he is only around 20 pounds. He seemed none the worst for wear afterwards, but it was touch and go there for awhile.
I've had all of my dogs go into convulsions eating Walnuts. I suspect they eat some of the hulls and some of the shell along with the nut meat. I believe the Tannin is what gets them.
You can't watch them 24/7 but you have to try.