I have been down with "the" flu since Friday. Found out last night throug casual conversation that while I was in a fog my dog got into a bowl full of grapes that was left on the coffee table and ate most of them. So my mom , who was here helping , gave him some more since he loved them and they are sooo healthy
I called the vet and they said if they were going to be an issue they would have by now..no runs , no ill effects , no vomiting..he is peeing like a racehorse as per usual. Absolutely nothing even off about him .
The vet said only some dogs are effected by grapes and they are not sure why? I thought they were fatal. I do not keep grapes or raisins in the house for that reason ( my mom did shopping for me and bought them for my son who loves fruit even more than any kind of candy).
Reading up on it I see that only 1/3 of dogs who eat grapes will have an issue and that is only documented from 1989 and on? Weird. They think it is a reaction to a fungus or pesticide maybe?
In any event I wont be testing it again and will put a list of no no foods on the fridge for dogs next time I am incapacitated .
My gut feeling is the pesticides, but I definitely haven't done the research. I had an australian shepherd that loved to pick our home grown grapes off the vine. He'd pick them and pinched the peel off, just eating the meat. He lived a long life and never had any medical issues.
I will not recommend continuing feeding grapes to your dog though, as from what I under stand, the grapes harm the kidneys. I assume this could be a slow process where the effect eventually adds up, damaging the kidney.
One thing that I would caution is your note about the peeing like a race horse. This could be a sign of trouble if he is peeing too much. He could be taking in more water and peeing more to flush whatever toxins are ingested from the grapes. I'm not saying this is the case either just a heads up. If the grapes are a cause of excessive urination, this overworking of the kidneys is not good.
Again, I offer all this as opinion. I have no medical background, I only have a minor in chemistry which involved some biochem.
No one on here can tell you for sure that the grapes will or will not harm your dog. Your best bet is to avoid them, and not stress if he gets a couple here or there. Mostly just be vigilant.