If your dog happened to eat one or two grapes then there's usually nothing to worry about.
The reason grapes harm dogs is through kidney failure but the kidney failure from eating grapes takes a few months to a year to happen.
Your dog would also have to eat more than a couple of grapes during that time period before it become a problem.
So your dog is not gonna die right away after eating a few grapes and it has happened to my dog as well.
A few years ago my dog ate 2 grapes that fell on the floor before I could pick them up.
I was worried so I took him to the vet and the vet said that just eating a couple grapes is not gonna harm him and not worry.
It's not that the grapes are directly poison to dogs it eventually leads to kidney disease and kidney failure in your dog if they eat more than a few grapes.
Don't feed your dog grapes but if the dog ate a couple grapes then the dog will likely be fine.
My dog is still healthy after 2 years have passed since he ate those two grapes.