Hello, my name is***** and I have over 20 years of experience as a veterinarian.
I understand that you are concerned about your girl eating grapes as they can be toxic to dogs, but they must eat a certain amount per pound of body weight to get sick.
Grapes can cause nausea, vomiting, diarrhea, then increased water consumption, lethargy, and kidney failure in dogs, but the toxicity is dose dependent meaning a big dog would have to eat more than a small dog.
Some dogs are more sensitive than others but a toxic dose is usually 3 grapes per kilogram of body weight (3 grapes per 2.2 pounds).
In very sensitive dogs they report that dangerous doses begin at about 0.18 ounces of grapes per pound of dog weight. That’s 1.8 ounces (one or two grapes) for a 10-pound dog, and 3.6 ounces (three or four grapes) for a 20-pound dog.
Raisins: About 0.07 ounces of raisins per pound of dog weight may be toxic. In real terms, that’s a mere 0.7 ounces of raisins for a 10-pound dog, and 1.4 ounces for a 20-pound dog.
I understand there is a lot of conflicting information out there. To be safe we recommend no grapes. But they do need to eat a certain minimal amount per pound of body weight.
If a dog eats grapes, even if the owner thinks that they only ate a few I always recommend that owners watch their pups for vomiting and/or diarrhea several hours later just in case the pup ate more then you thought she did. Signs of toxicity usually occur with 12 to 24 hours, but in some cases it takes up to 48 hours. Further signs of toxicity include lethargy, lack of appetite, abdominal pain, increased water consumption and finally lack of urine production.
I tell owners if they see vomiting and diarrhea with any amount of grapes fed we need to get them on intravenous fluids to protect the kidneys.
In short grapes are sweet, and most dogs have a huge sweet tooth so they love them. But they can be toxic, so I don't recommend that you give them to your girl any more. I don't think you've done any damage with the few she's eaten, but I am pleased she won't be eating any more.
Best of luck with your girl, please let me know if you have any further questions.