Onion (Never Give to Pets)
タマネギ (tamanegi)
Definition
A vegetable in the allium family that is generally considered toxic to dogs and cats. The compound responsible damages red blood cells and is not destroyed by cooking, so soups and broths made with onion carry the same risk.
Key points
- Onions, along with garlic, leeks and chives, contain compounds that damage red blood cells in dogs and cats
- Cooking, drying or blending does not remove the compound, so broths, soups and sauces made with onion carry the same risk as the raw vegetable
- Symptoms of anemia can take a few days to appear rather than showing up right away
- There is no amount considered clearly safe, so any suspected ingestion is treated as a reason to call a veterinarian
What is onion, and why does it matter for pets?
Onion is a kitchen staple in human cooking, but it belongs to a family of vegetables, along with garlic, leeks and chives, that is generally considered toxic to dogs and cats. It sits alongside xylitol as one of the clearest examples of a food that is completely normal for people and dangerous for pets.
Never give it, in any form
The compounds in onion are thought to cause oxidative damage to red blood cells, leading to a form of anemia in dogs and cats. This is not destroyed by heat, drying, or blending. A stew simmered with onion, a broth strained to remove the pieces, or a sauce built on a sauteed onion base all carry the same risk as the raw vegetable, because the compound has already dissolved into the liquid.
There is no dose considered clearly safe, and sensitivity varies between individual animals and is affected by body size. If a dog or cat may have eaten onion, garlic, leek or chive in any form, contact a veterinarian rather than watching for symptoms at home.
Signs can take days to show
Unlike some toxic foods that cause an immediate reaction, the anemia from onion ingestion often develops over a few days. Early signs can include lethargy, pale gums, and darker than usual urine. Looking normal on the day of ingestion is not a reliable sign that everything is fine, which is part of why this food catches owners off guard.
Where it hides
- Raw or cooked onion, garlic, leek, chive and shallot
- Stews, curries, meat sauces and soups made with any of the above
- Broth or pan drippings left over after cooking with onion, even once the solid pieces are removed
- Prepared foods and takeout dishes where onion is an easy-to-miss ingredient
The safest approach is to keep table food, including sauces and broths, out of a pet's diet altogether rather than trying to pick out the onion pieces.
This entry shares general knowledge and is not veterinary advice. It is not intended to diagnose, treat or prevent any condition. If you have concerns about your dog or cat, please consult your veterinarian.
FAQFrequently asked questions
Can dogs eat onions in small amounts?
No amount is considered clearly safe. Onion toxicity is dose dependent, but the threshold varies by individual, and a small dog is affected by far less than a large one. Any suspected ingestion is generally treated as a reason to call a veterinarian rather than wait and see.
Is cooked onion safe for dogs and cats?
Cooking does not destroy the compound responsible for the toxicity. Onion that has been fried, boiled or simmered into a dish, and even the broth or sauce it was cooked in, is considered just as risky as raw onion.
Is onion toxicity the same for cats as for dogs?
Cats are affected by the same mechanism and are generally considered at least as sensitive as dogs, if not more so. Onion, garlic, leek and chive should all be kept away from cats as well.
My dog ate onion and still seems fine. Is it out of danger?
Signs of anemia from onion ingestion can take a few days to appear, so looking fine right after eating it is not considered a sign of safety. A veterinarian should be contacted as soon as ingestion is suspected.