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Grape and Raisin Toxicity Calculator for Dogs

Grapes and raisins can cause sudden kidney failure in dogs. Unlike chocolate or xylitol, the effect does not follow the dose in a predictable way: many dogs that eat grapes never become ill, while some develop kidney failure, and which dogs will be affected cannot be predicted. No safe amount has been established. This calculator only shows how the amount compares with the smallest doses reported in poisoned dogs; whatever the result, the next step is the same.

Call your veterinarian or the nearest emergency hospital now if your pet ate grapes, raisins or currants, even a few. Do not wait for symptoms. For dose advice, the 24/7 animal poison lines: ASPCA (888) 426-4435 or Pet Poison Helpline (855) 764-7661 (a consultation fee may apply).

A small snack box of raisins is printed with its weight. If you are unsure, enter the larger amount.

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How this is calculated

By count, the calculator compares the number of fruits with the rough guide in the Merck Veterinary Manual: more than one grape or raisin per 10 lb (4.5 kg) of body weight may be enough to put the kidneys at risk. By weight, it divides the grams eaten by your dog’s weight in kg and compares the result with the smallest doses reported to have caused acute kidney failure.

Smallest reported toxic amountValue
Raisins2.8 g/kg (used here)
Grapes19.6 g/kg
Grapes or raisins, not specified0.32 to 0.65 oz/kg, about 9 to 18 g/kg; about 9 g/kg used here for grapes
Rough guide by countMore than 1 fruit per 10 lb (4.5 kg)

These figures come from individual cases collected by poison centers, not from studies that found a safe level. Where sources differ, the calculator uses the lower figure.

Why no amount is safe

  • The cause is still debated. Tartaric acid, present in high concentrations in grapes, is one proposed toxic principle; an individual, unpredictable reaction has also been proposed.
  • Vomiting can start within 2 hours, with diarrhea, lethargy and thirst within 5 to 6 hours. Kidney failure may appear within 24 hours or several days later.
  • Seedless and seeded grapes, store-bought and backyard fruit, and grape pressings from wineries have all been involved.
  • Treatment works best early: making the dog vomit soon after eating, then fluids and kidney monitoring for 48 to 72 hours.
  • Kidney failure in cats and ferrets after eating grapes or raisins has been reported anecdotally; call about any species.

Sources

  • Merck Veterinary Manual, “Grape, Raisin, and Tamarind (Vitis spp, Tamarindus spp) Toxicosis in Dogs,” C. Hayes, ASPCA Animal Poison Control Center; full review September 2024. Rough guide by count, tartaric acid, cats and ferrets.
  • P. A. Eubig and others, “Acute renal failure in dogs after the ingestion of grapes or raisins: a retrospective evaluation of 43 dogs (1992–2002),” Journal of Veterinary Internal Medicine, 2005, as cited by A. Schweighauser and others, Journal of Veterinary Internal Medicine, 2020. Smallest reported doses of 19.6 g/kg and 2.8 g/kg.
  • K. McKnight, “Grape and raisin toxicity in dogs,” Toxicology Brief, Veterinary Technician, February 2005, ASPCA Animal Poison Control Center. Smallest documented dose of 0.32 to 0.65 oz/kg, timing of signs, treatment.

Reviewed November 2026. This calculator gives an estimate, not a diagnosis, and does not replace a veterinarian. Published doses come from case reports and poison-center experience; individual animals differ.

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