- Allium — the green tops count too
- Often delayed 1+ day
- Affects: Red blood cells
Why this verdict for dogs
Green onions (scallions) are part of the allium family and are toxic to dogs, damaging red blood cells.
Warning signs to watch for
- Weakness
- Pale gums
- Reddish urine
⚠ If your dog ate green onion
Act immediately — don't wait for symptoms.
- Call your vet or a pet poison helpline right away.
- Note how much was eaten and when.
- Do not induce vomiting unless a professional tells you to.
Green onions — scallions or spring onions — are scattered raw over so many dishes that they are one of the easiest ways for an allium to reach a pet. The green tops are just as toxic as the white bulb, which surprises people who assume the leafy part is only a garnish.
How much is safe?
None is safe for dogs or cats, and both the raw and cooked forms carry the toxin equally. As a family benchmark, meaningful red blood cell damage becomes likely once a pet eats around 0.5% of its body weight in onion — for a 5 kg cat, that is roughly 25 grams, a small handful. Cats are considerably more sensitive than dogs. Dried and powdered forms are far more concentrated than fresh, which is why seasoned takeaway food is worse than a stray raw slice.
What happens if a dog eats too much?
The damage is to red blood cells and it is deliberately slow to appear. There may be vomiting or diarrhoea in the first few hours, then an apparently normal day or two, then the anaemia declares itself: lethargy, weakness, reluctance to walk, pale or yellow-tinged gums, rapid breathing, a fast heart rate and urine that looks orange, red or brown. Severe cases need a transfusion.
⚠ What to do if your dog ate green onion
Call your vet or a poison line with your pet's weight and the amount eaten (ASPCA 888-426-4435 · Pet Poison Helpline 855-764-7661). Do not wait for signs. If it was recent, decontamination may help; after that the plan is usually bloodwork now and repeated in two to five days, because catching the anaemia early is far better than discovering it when a pet collapses.
⚠️ Worried your pet got into this?
Frequently asked questions
My dog ate a few green onion pieces from a stir fry — how worried should I be?
Call with the weight and amount. The stir fry likely contained garlic and onion too, so the total allium dose is usually higher than the visible green onion suggests.
Are the green tops safer than the white part?
No. Both contain the toxic compounds. There is no safe part of the plant.
More vegetables for dogs
By the CanMyPet Editorial Team · Reviewed against ASPCA Animal Poison Control, the American Kennel Club (AKC) and Pet Poison Helpline · Last updated July 31, 2026.
Sources
- ASPCA — People Foods to Avoid Feeding Your Pets
- American Kennel Club — Dog Nutrition
- Pet Poison Helpline — Poison List