What dogs can't eat: dangerous doses of chocolate, xylitol and grapes by dog weight

For a 10 kg dog, signs of chocolate poisoning are possible from as little as 25 g of dark chocolate (70–85% cocoa) or 100 g of milk chocolate. This is the threshold of 20 mg of theobromine per kilogram of body weight, below which clinical signs are rarely described. It is a guide for when to call a vet, not a permission: dogs differ in sensitivity, and age and heart disease lower the threshold. Xylitol is dangerous from 0.1 g per kg: for the same dog that is 1 g, and from 5 g acute liver failure is possible.

Below is a table for 5, 10, 20 and 40 kg dogs across four types of chocolate, thresholds for xylitol, grapes and macadamia, and what to do in the first two hours. All figures come from the USDA database and peer-reviewed veterinary publications; references are at the end.

See also: Dog treats · Diarrhea in dogs

How much chocolate is dangerous for a dog?

It is not chocolate itself that poisons, but theobromine, a cocoa alkaloid that dogs eliminate several times more slowly than humans. So what matters is not "a small piece" but grams of theobromine per kilogram of body weight. Dark chocolate with 70–85% cocoa contains 802 mg per 100 g, milk chocolate 205 mg, unsweetened baking chocolate 1,600 mg, and cocoa powder 2,060 mg.

In a British analysis of 185 calls to vets, doses below 20 mg/kg were classified as rarely causing clinical signs. Divide 20 mg by the theobromine content and you get the grams at which risk begins:

This is not a "lethal dose" but the level at which symptoms appear: agitation, tremors, vomiting, rapid breathing, a fast heart rate. In a series of 156 dogs that ate chocolate, 44 had symptoms, and 28 of them had eaten dark or bittersweet chocolate. After induced vomiting, a sorbent and supportive care, 43 of the 44 symptomatic dogs survived; mortality across the whole series was under 3%.

10 g of cocoa powder for a 10 kg dog is the dose at which symptoms become likely. Milk chocolate is 10 times less dangerous, but for a 3 kg dog its limit is about 30 g.

Why is xylitol more dangerous than sugar?

Xylitol is a sugar substitute found in chewing gum, "diet" candy, some peanut butters and toothpastes. In dogs it triggers a sharp release of insulin: blood glucose drops, and weakness, a wobbly gait and seizures appear. The risk of hypoglycemia starts at 0.1 g per kg of body weight, and of acute liver failure at 0.5 g per kg.

For a 5 kg dog that is 0.5 g and 2.5 g, for 10 kg it is 1 g and 5 g, for 20 kg it is 2 g and 10 g. In a study of 95 dogs after xylitol ingestion, liver damage developed in 49.5%, and it was less common in those whose vomiting was induced in time.

A pack of sugar-free gum on the floor is a reason to call a vet right away, not to wait and watch.

Grapes and raisins: why is there no safe dose?

Grapes and raisins cause acute kidney failure. In a series of 10 cases, the dogs had eaten from 3 g of dry matter per kilogram of body weight, but that is not a safety limit: amounts across the cases varied many times over. The most likely cause is tartaric acid, and its content varies between varieties and batches.

That is why the veterinary literature gives no "safe amount": one dog tolerates a bunch without consequences, another ends up on dialysis after a few berries. In a 2026 multicenter analysis, two thirds of dog cases involved processed grapes, meaning raisins in baked goods, with a peak in December.

Any amount of grapes or raisins is a risk, including in muffins and muesli.

Macadamia nuts: what happens and how fast?

There were no deaths after macadamia in the described series, but it puts a dog out of action for a day or two: hind leg weakness, tremors, depression, raised temperature. In 79% of documented cases symptoms appeared within 12 hours, and the average amount eaten was 11.7 g of nuts per kilogram of body weight. That is the average in the described cases, not a safety threshold: no minimum dangerous dose has been established. The mechanism is still unknown, and no other nut does this.

The symptoms are frightening but pass; with trembling and weakness, go to the vet for supportive care.

Onion and garlic: why does the damage not show right away?

Organosulfur compounds in onion and garlic oxidize hemoglobin and destroy red blood cells, leading to hemolytic anemia. Raw, cooked and dried forms are all dangerous: in a laboratory study, granulated garlic damaged dog red blood cells just as fresh garlic did. A fatal case after raw cloves has been described.

Symptoms are delayed by 1–5 days: pale gums, weakness, dark urine, rapid breathing. We do not give an exact toxic threshold in grams: in open sources it is not confirmed by primary research, and the difference between varieties is large. The practical rule is that there should be no onion or garlic in a dog's bowl in any amount, including baby food purée and bouillon cubes.

Onion-induced anemia shows up after several days, so if your dog ate food from the table and became lethargic, tell the vet.

What should you do in the first two hours?

First, assess the situation in grams: what exactly, how much, when. The wrapper or leftover product will help the vet calculate the dose using the table above. Second, call the clinic before symptoms appear: while the substance is still in the stomach, the vet can induce vomiting and give a sorbent. With chocolate and xylitol this changes the prognosis; with grapes it is the only chance to avoid kidney damage.

What not to do: do not induce vomiting with salt water or a finger without a vet's instruction, and do not give milk, oil or "activated charcoal from the medicine cabinet" by guesswork. Even a sorbent has a dose: in a clinical case, an overdose of charcoal with sorbitol in a dog after chocolate led to severe hypernatremia.

And about treats in general: everything a dog gets outside its food should fit within 10% of its daily calorie allowance. We explained how to calculate this in our article on feeding amounts. More articles are on our blog.

A call to the vet in the first two hours costs less than any treatment afterward.

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