Can dogs and cats eat Onion?
Onions damage red blood cells and can cause anaemia in dogs and cats. Cats are more sensitive than dogs. Raw, cooked, dried and powdered onion are all harmful.
Why
N-propyl disulfide and other organosulfur compounds (oxidative damage to red blood cells)
Signs to watch for
- vomiting
- lethargy, weakness
- pale gums
- fast breathing
- red or brown urine
- loss of appetite
Good to know
Effects can build up over several days or after repeated small amounts. Watch for onion powder in gravy, stock cubes, baby food and leftovers.
If you think your pet has been poisoned
If you suspect your dog or cat has eaten or touched something poisonous, contact your vet or the nearest emergency veterinary clinic immediately, even if your pet seems fine – some poisons take hours or days to show signs, and early treatment works best. Do not try to make your pet vomit unless a vet tells you to, as this can cause more harm. Take the packaging, label or a piece of the plant with you, and note what was eaten, roughly how much, and when.
Sources
Sources
- Merck Veterinary Manual – Garlic and Onion (Allium spp) Toxicosis in Animals
- PDSA – Onion and garlic poisoning in dogs
- ASPCA – People Foods to Avoid Feeding Your Pets
- Cats Protection – Cats and human foods
Checked against these sources in October 2026.