How much onion or garlic is toxic to dogs?

Toxic effects can begin when a dog eats onion or garlic equal to about 0.5% of its body weight — roughly 5 grams per kg for onion. Garlic is several times more potent. Cooked, raw, and powdered forms are all toxic.

What are the symptoms of onion or garlic poisoning in dogs?

Vomiting, diarrhea, and abdominal pain early on, then weakness, pale gums, rapid breathing, and dark or red-tinged urine as red blood cells are destroyed — often delayed by a few days.

Is garlic worse than onion for dogs?

Gram for gram, garlic is roughly five times more concentrated than onion, so a smaller amount of garlic can cause harm.

Onion & Garlic Toxicity Checker

Did your dog eat onion or garlic? Check the risk by weight and amount eaten.

🚨 Onion and garlic poisoning can be delayed for days. If your dog ate a meaningful amount, call your vet or: ASPCA Animal Poison Control (888) 426-4435 or Pet Poison Helpline (855) 764-7661 (US).

Dog's weight

What did your dog eat?

Amount eaten (grams) A medium onion is ~150 g; one small wedge ~25 g.

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Why onion and garlic are toxic to dogs

Onions, garlic, leeks, and chives belong to the Allium family. They contain compounds (organosulfur, n-propyl disulfide) that damage a dog's red blood cells, leading to a type of anemia. All forms are toxic — raw, cooked, fried, dehydrated, and powdered — and powders are especially concentrated. Toxicity is dose-dependent and can build up from repeated small amounts (for example, table scraps or seasoned food).

Toxic thresholds

Onion: signs can begin around 5 g per kg of body weight (about 0.5% of body weight).
Garlic: roughly 5× more potent than onion (about 1 g per kg).
Powders are far more concentrated than fresh — a small amount goes a long way.

Symptoms to watch for

Early on: vomiting, diarrhea, drooling, and abdominal pain. Over the following days, anemia develops — look for weakness, lethargy, pale or yellowish gums, rapid breathing or heart rate, and reddish-brown urine. Because signs can be delayed several days, don't assume your dog is fine just because they seem okay at first.

⚠️ This is an estimate based on average thresholds. Seasoned human food (soups, sauces, baby food, garlic bread) often contains hidden onion/garlic. When unsure, contact your vet or poison control.

Frequently asked questions

Is a tiny bit of garlic in dog food or treats dangerous?

Very small amounts used as flavoring are generally below toxic thresholds, but there's no clear benefit and sensitive dogs (and certain breeds like Japanese breeds) are more at risk. It's safest to avoid it.

My dog ate garlic bread — should I worry?

It depends on the amount and your dog's size. Garlic bread also brings fat and sometimes onion. Use the checker above and call your vet if the result is concerning.

How soon do symptoms appear?

Stomach upset can be same-day, but the more serious anemia often develops over 1–5 days.