Can dogs eat onion?
No — onion, garlic, leeks, chives, and shallots (the allium family) damage dog red blood cells. Cooked, raw, and powdered forms are all toxic. Onion powder hidden in gravy, pizza, or baby food is the sneakiest source.
All allium plants contain sulphur compounds that cause red blood cells to rupture in dogs (and cats, more severely). Toxicity develops over 1–3 days, so a dog who seems fine after eating pizza crust may decline later.
Watch out for
- Dogs: toxic dose around 15–30g onion per kg bodyweight; garlic is ~5× more potent.
- Cooking does not break down the toxin.
- Hidden sources: gravy, stuffing, baby food, baked beans, onion rings, garlic bread, curry leftovers.
- Symptoms (pale gums, weakness, dark urine) typically appear 1–3 days after eating.
- Garlic supplements marketed as "natural flea treatment" contain dangerous doses — don't use.
Frequently asked
Is a tiny bit of onion really dangerous?
Large dogs usually tolerate incidental tastes. The risk rises sharply with repeated exposure or larger portions — a pizza crust weekly is more dangerous than one accidental bite.
Is garlic safe as a flea repellent?
No. The doses recommended online for natural flea treatment fall within the toxic range. Use licensed flea products; they work and are far safer.
My dog ate leftover curry — what should I do?
Call your vet. Most curries contain onion and garlic in concentrated amounts. Have the dog's weight and the rough quantity eaten ready.
Does cooking onion make it safer?
No. The allium compounds are heat-stable — cooked onion is as toxic gram-for-gram as raw.
When should I see a vet?
Any confirmed significant ingestion warrants a call. Symptoms develop over days — don't wait. Bloodwork at 24h and 72h checks for anemia developing.
More food guides
Check our toxic-food tool for quick answers, or ask CRO about your specific dog.
This guide is educational and based on US veterinary sources. Individual dogs react differently — introduce any new food slowly, and speak to your vet if your dog has medical conditions like pancreatitis, diabetes, or allergies.