Did my dog or cat eat too much onion or garlic?
In dogs, signs of onion poisoning have followed 15 to 30 g of onion per kg of body weight; cats react to as little as 5 g/kg. Garlic is 3 to 5 times more toxic than onion, and dried powders are far stronger than fresh.
Free, no sign-up · Reviewed October 2026 · How it works
Pet
What was eaten
A medium onion weighs about 150 g; a garlic clove about 3–5 g; a teaspoon of powder about 3 g.
Share of the level linked to poisoning
33%
About 5.0 g of onion-equivalent per kg. Signs have been seen in dogs after 15–30 g/kg.
The powder and garlic multipliers are approximations; individual sensitivity varies, and Japanese breeds such as Akitas and Shibas are thought to be more sensitive.
For information only, not a diagnosis or a substitute for your vet. If your pet seems unwell or you're worried, call your vet.
How this tool works
The calculator converts what was eaten into an onion equivalent: garlic counts as 5 times onion (the cautious end of the 3 to 5 times in the Merck Veterinary Manual), and dried onion or garlic powder as about 8 times fresh, because fresh onion is mostly water. The powder figure is our approximation.
It divides that by your pet's weight and shows it as a share of the level at which signs have been reported: 15 g/kg for dogs and 5 g/kg for cats.
Onion and garlic damage red blood cells over several days, and repeated small amounts add up, so watch your pet for up to 5 days and call your vet if in doubt.
Questions.
How much onion is toxic to a dog?
Signs have been reported after 15 to 30 g of raw onion per kg of body weight, so about 150 g (one medium onion) could affect a 10 kg dog. Smaller amounts eaten repeatedly can also cause problems.
Is garlic bad for dogs?
Yes. Garlic is 3 to 5 times more toxic than onion. A small amount of garlic cooked into food is unlikely to harm a large dog, but avoid feeding it and keep garlic powder and supplements away.
What are the signs of onion poisoning?
Weakness, pale gums, fast breathing, red-brown urine and sometimes vomiting, usually appearing 1 to 5 days after eating.
Related tools
- Can my dog or cat eat this? Toxic food checkerCheck over 50 common foods: which are safe, which need care and which are toxic to dogs and cats, from chocolate and grapes to cheese and peanut butter.
- My dog ate chocolate: how much is dangerous?Enter your dog's weight, the type of chocolate and how much they ate to see the dose in mg/kg and whether to call a vet now.
- My dog ate gum: xylitol toxicity calculatorWork out how much xylitol your dog ate from gum, mints or a label, and whether it reaches the level that causes low blood sugar or liver damage.
- Dog and cat symptom checkerCheck your dog's or cat's symptoms and see how urgent they might be: emergency now, vet soon, or monitor at home.
