For years the exact toxin was a mystery. Recent veterinary work points to tartaric acid, which is naturally present in grapes and varies with the fruit's ripeness — which may explain why the effect seems so unpredictable. What is certain is the outcome in affected dogs: injury to the kidneys that can progress to complete kidney failure if untreated.
Early signs appear within about 12 to 24 hours and look deceptively mild — vomiting, poor appetite, lethargy, diarrhea. The serious kidney damage develops over the following one to two days, sometimes with increased thirst and urination at first, then less and less urine as the kidneys shut down. Dogs treated promptly, before symptoms take hold, have a much better prognosis, which is why speed matters more here than with almost any other food.
Sources
- Grape, Raisin, and Currant Poisoning in Dogs — VCA Animal Hospitals
- People Foods to Avoid Feeding Your Pets — ASPCA Animal Poison Control
This page is informational and is not veterinary advice. If your pet has eaten something risky, contact your vet or an animal poison control line right away.