Red: toxic
No, onions are toxic to dogs. The ASPCA lists culinary onions as toxic to dogs, whether raw, fried or powdered in seasoning.
Why onions are dangerous
Onions belong to the Allium genus, like garlic, chives and leeks. According to the MSD Veterinary Manual, they release sulphur-containing substances when cut, cooked or chewed. These substances damage red blood cells, causing anaemia. The delay is deceptive: significant red blood cell destruction usually starts only 3 to 5 days after ingestion. Concentrated forms such as crispy fried onions, onion powder or packet soups are particularly often involved. According to a review article, some breeds, including Akitas and Shibas, are considered more sensitive.
What are the signs?
The MSD Veterinary Manual lists lethargy, loss of appetite, rapid breathing, a racing heart, weakness, poor stamina, yellowish mucous membranes and reddish urine, with collapse in the worst cases. The ASPCA also lists vomiting.
What to watch for
- Check leftovers: Sauces, soups and ready meals may contain onions or onion powder.
- Garlic counts too: According to MSD, it is even more potent than onion.
What if your dog has eaten onions?
Call your vet or an emergency veterinary service immediately, even if your dog still seems lively. Have these details ready: what was eaten (raw, cooked, powdered or in a ready meal), roughly how much, when it happened and how much your dog weighs. Do not give home remedies or induce vomiting yourself. Monitor your dog closely over the following days.
If you suspect poisoning, take your dog to a vet or an emergency veterinary service immediately.
Snacks count towards the daily food allowance. Our free food calculator works out how much your dog needs, and you can find a complete feeding plan with guidelines for treats in our book “Hundeernährung und Futterplan” (book in German). New to life with a puppy? Our free Puppy Starter Pack can help. And if you would love to see your dog on your living room wall, explore our dog portraits from your own photo, available as a framed portrait or digital file.
Further reading
- Christmas with your dog: what to arrange beforehand
- Puppy checklist: essentials and the first 3 days
- Calculating your dog’s food allowance: how much your dog really needs
Sources, accessed on 20.10.2026: ASPCA Animal Poison Control, Toxic and Non-Toxic Plants: Onion (Allium cepa), Toxic to Dogs; ASPCA, People Foods to Avoid Feeding Your Pets (Onion, Garlic, Chives); MSD Veterinary Manual, Garlic and Onion (Allium spp) Toxicosis in Animals; Cortinovis and Caloni, Household Food Items Toxic to Dogs and Cats, Frontiers in Veterinary Science 2016.
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