Dog Raisin and Grape Toxicity Calculator
Enter your dog's weight and the amount of grapes or raisins eaten to see the dose per kilogram of body weight, how that compares to the lowest reported toxic dose, and an actionable risk level. Supports fresh grapes, raisins, sultanas, currants, and cream of tartar. Switch between metric and imperial, and between counting pieces or entering grams.
Why are grapes and raisins toxic to dogs?
The exact toxic mechanism is still debated, but the leading hypothesis points to tartaric acid and its salt potassium bitartrate (cream of tartar) as the culprits. Both compounds are present in high concentrations in grapes and their dried forms, and dogs appear to have limited ability to metabolize tartaric acid safely. Even a small amount of cream of tartar given to dogs in experimental settings causes the same acute kidney injury (AKI) seen after grape ingestion. Tartaric acid concentration in grapes varies between 0.35% and 2.0% depending on variety, ripeness, and growing conditions, which helps explain why the same quantity can cause severe poisoning in one dog and no symptoms in another.
How is the toxic dose calculated?
Veterinary poison control databases record the lowest dose at which kidney injury has been documented. For raisins and other dried grape products, that figure is 2.8 grams per kilogram of body weight - the dose described in the clinical literature alongside confirmed acute kidney injury. For fresh grapes the threshold is approximately 19.6 g/kg, reflecting their lower tartaric acid concentration per gram. This calculator divides the total grams eaten by the dog's weight in kilograms to produce a dose in g/kg, then expresses it as a percentage of the threshold. A result at or above 100% means the documented toxic dose has been reached. However, because individual sensitivity varies widely, even a small dose warrants a call to a vet.
What to do if your dog ate grapes or raisins
Speed is the most important factor. If the ingestion was within the past two hours, a veterinarian can often induce vomiting and administer activated charcoal to limit absorption before the toxin reaches the kidneys. After two hours, vomiting is less effective and monitoring becomes critical. Key symptoms to watch for in the 6-72 hours after ingestion include vomiting and diarrhea (often within 6-12 hours), lethargy and weakness, loss of appetite, reduced or absent urination (a sign of kidney failure), abdominal pain, and tremors or seizures. Kidney failure typically develops within 24-72 hours, and dogs that survive the acute phase may need intravenous fluids and hospitalization. Never wait for symptoms to appear before calling a vet - by the time symptoms are visible, significant kidney damage may already have occurred.
Metric and imperial units explained
All toxicology thresholds are expressed in grams per kilogram of body weight (g/kg) because that ratio scales correctly across dog sizes. This calculator accepts weight in pounds or kilograms and converts internally. A 22 lb (10 kg) dog reaches the raisin toxic threshold at about 28 g of raisins - roughly 28 standard raisins. A 66 lb (30 kg) dog reaches it at about 84 g, or roughly 84 standard raisins. Larger dogs are not "safe" - they simply need more grams to reach the threshold, but their kidneys are equally vulnerable once the dose is reached.
Toxic dose thresholds for grapes and related foods
| Food | Toxic threshold (g/kg) | Notes |
|---|---|---|
| Fresh grapes | 19.6 | Cases of AKI documented from as few as 4-5 grapes in small dogs |
| Raisins | 2.8 | Concentrated ~7x vs fresh; lowest reported dose with AKI |
| Sultanas / golden raisins | 2.8 | Similar concentration to standard raisins |
| Currants (Zante) | 2.8 | Small but concentrated; same threshold applied clinically |
| Cream of tartar | Any amount | Pure tartaric acid salt - immediate veterinary emergency |
| Grape juice / jelly / seed oil | Not established | No confirmed cases of AKI from these forms |
Lowest reported doses associated with kidney injury in dogs. Any amount should be taken seriously given the unpredictable individual response.
Frequently asked questions
Can one raisin hurt my dog?
Potentially, yes. While most documented toxicity cases involve multiple raisins or grapes, individual sensitivity varies enormously. Some dogs have developed acute kidney failure from just a handful of grapes. Veterinary poison control centers recommend treating any raisin or grape ingestion as a potential emergency rather than waiting to see if symptoms develop.
Are grapes or raisins more dangerous?
Raisins are more dangerous per gram because they are dried and concentrated. A raisin weighs roughly one-seventh of the fresh grape it came from, meaning raisins deliver the same toxic load in a much smaller volume. The toxic threshold for raisins is 2.8 g/kg versus about 19.6 g/kg for fresh grapes. Sultanas and currants are treated the same as raisins by veterinary toxicologists.
My dog ate grapes a few hours ago and seems fine - should I still call a vet?
Yes. Up to 72% of dogs that ingest grapes show no immediate symptoms, but can still develop kidney failure over the following 24-72 hours. The absence of early symptoms does not mean the kidneys are unaffected. A vet can run blood and urine tests to catch early kidney changes before they become irreversible.
Does cooking or processing make grapes safer for dogs?
No. Raisins, sultanas, currants, and cooked grape products such as grape jam, pie filling, and fruitcake are all still toxic. The toxic agent (tartaric acid) remains after drying and cooking. Grape seed oil and grape juice have not been confirmed to cause toxicity, but they have not been proven safe either, and most vets recommend avoiding them.
Are all dog breeds equally sensitive?
The current evidence does not show breed-specific differences in sensitivity. Age, pre-existing kidney disease, and hydration status may all affect how a dog responds, but no breed has been shown to be reliably resistant. Do not assume a large or healthy-looking dog is safe.
What is the Pet Poison Helpline number?
In the United States, the Pet Poison Helpline is available 24 hours a day at (855) 764-7661. The ASPCA Animal Poison Control Center can be reached at (888) 426-4435. Both services charge a consultation fee but provide immediate expert guidance. In life-threatening cases, go directly to an emergency veterinary clinic.