Common human foods -- chocolate, onions, grapes -- can be toxic to your pets

  • Chocolate in any form can be toxic to your dog.

    Chocolate in any form can be toxic to your dog. Courtesy of Diana Stoll

By Diana Stoll
On Pets
Posted3/16/2020 6:00 AM

The third week in March has been designated National Pet Poison Prevention Week as an extension of National Poison Prevention Week, first promoted in 1961 by the National Safety Council. It's a good time to consider what kinds of human food put curious pets at risk.

There are a number of foods that are perfectly safe (and delicious) for human consumption, but are poisonous to pets.


First up: Chocolate contains theobromine, which is quickly metabolized by people but processed much slower by dogs and cats, allowing it to rise to toxic levels.

Dark chocolate, baking chocolate and cocoa have the highest levels of theobromine; white chocolate and milk chocolate have the lowest. Even a small amount of dark chocolate can cause seizures, an irregular heartbeat, internal bleeding and death. The same amount of milk chocolate may just cause vomiting and diarrhea.

The size of the pet is also a factor in chocolate poisoning. A 150-pound mastiff will be less affected than a 10-pound terrier or tabby when ingesting the same amount of chocolate. If you suspect your pet has eaten any type or amount of chocolate, call your veterinarian immediately. Inducing vomiting within an hour or two of ingestion may be critical.

People are often surprised to discover raisins and grapes are toxic for pets, but they can cause kidney failure. It is unclear what substance in them is responsible for their toxicity (and not all dogs and cats are equally susceptible), but a handful of grapes can be lethal for a 50-pound dog.

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Early treatment by a veterinarian is important. She may induce vomiting and give activated charcoal to absorb toxins and intravenous fluids to support the kidneys.

What could be harmful about sharing a piece of pizza with Fido? Plenty, if the pizza has onions and garlic.

Garlic and onions contain disulfides and thiosulphates that cause damage to red blood cells, causing vomiting, diarrhea and anemia. All parts of them are toxic, including the leaves and flesh, and in all forms -- raw, cooked and powdered.

It only takes a small amount of garlic or onions to poison a dog or cat. A pet's weight and breed may also play a role in onion toxicosis. Cats are more sensitive than dogs. Garlic is more potent than onions, and garlic and onion powders are more toxic than fresh onions.

Depending on how the garlic or onions were consumed, inducing vomiting may or may not be helpful. Your pet may need supportive care while his body works to replace damaged red blood cells. If the damage is severe enough, he may even need a transfusion.


Several food products, including some sugar-free gum, candy, baked goods and toothpaste, contain xylitol to sweeten them. Even in small amounts, xylitol is very dangerous for dogs, quickly causing low blood sugar and leading to damage of the liver.

If you suspect your dog has ingested xylitol, call your veterinarian immediately. Tests to check your dog's blood sugar levels and liver enzymes will be run and intravenous fluids may be necessary.

These are the most common foods people have in their kitchens that are toxic to pets, but there are others, including Macadamia nuts, avocados and more.

The best way to celebrate National Pet Poison Prevention Week and protect your pets is to keep toxic foods out of their reach and don't share your dinner or dessert with them.

• Diana Stoll is the Practice Manager at Red Barn Animal Hospital with locations in Hampshire and Gilberts. Visit, or call (847) 683-4788 (Hampshire) or (847) 422-1000 (Gilberts).

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