Tip: a medium onion is about 110 g; one garlic clove is about 3 g. Dried powders are far more concentrated, so small amounts count.
This is an estimate only, not a diagnosis. Because signs can be delayed for days, when in doubt call your vet or a pet poison helpline.
Talk to a vet now — from home
Onion and garlic damage builds over days, so early advice helps. An online vet can triage quickly, and pet insurance can cover the visit.
Why onion and garlic are toxic to pets
Onions, garlic, leeks, chives and shallots (the Allium family) contain compounds that damage red blood cells, leading to a type of anemia. All forms count — raw, cooked, fried, dried and powdered — and powders are the most concentrated. Cats are more sensitive than dogs, and the worrying part is that symptoms can be delayed by several days.
As a rough veterinary guide, measured as grams of onion-equivalent per kilogram of body weight:
- Under ~5 g/kg — lower risk, but worth a call, especially for cats.
- ~5–15 g/kg — red-blood-cell damage becomes likely — call your vet.
- Over ~15 g/kg — significant risk of anemia — treat as an emergency.
Garlic and dried powders are far stronger by weight than fresh onion, so this tool converts everything into an "onion-equivalent" and applies an extra margin for cats. Treat the result as a cautious estimate, not a verdict.
What to do if your pet ate onion or garlic
- Call your vet or a pet poison helpline — don't wait for symptoms, which can take days.
- Note the type (fresh, cooked, powder) and amount eaten, and when.
- Watch for weakness, pale gums, lethargy, and reddish or brown urine.
For full guides, see Can dogs eat onion? and Can dogs eat garlic?