Here in the P-O, we live amongst the vines but some grapes and raisins are believed to have a high toxicity for dogs, and can cause kidney failure.
The most common early symptom of grape or raisin toxicity is vomiting, usually within a couple of hours after ingestion.
Other symptoms to watch out for are loss of appetite, lethargy, and dehydration (test by gently pulling up on the skin of the dog’s neck. It should spring back immediately.)
Research isn’t clear but it is possible that a mycotoxin (a toxic substance produced by a fungus or mold) may be the cause.