Are Onions Poisonous to Dogs?
Allium cepa · Liliaceae (Amaryllidaceae; genus Allium)
Highly ToxicAlso toxic to cats
Onions are highly toxic to dogs.
Why it's toxic
The toxic compounds in onions:
- N-propyl disulfide
- Organosulfur oxidant compounds (thiosulfates/sulfoxides) that cause oxidative damage to red blood cell membranes
Symptoms to watch for
If your dog ate onions, watch for:
- Vomiting
- Diarrhea
- Decreased appetite
- Abdominal pain
- Drooling
- Depression/lethargy
- Hemolytic anemia (Heinz body anemia) from breakdown of red blood cells
- Blood/red-colored urine (hemoglobinuria)
- Pale gums
- Weakness and exercise intolerance
- Elevated heart rate
- Increased respiratory rate, effort, and panting
- Collapse
- Kidney damage
- Death in severe cases
What to do if your dog ate it
- 1Remove your dog's access to the onions and check how much may have been eaten.
- 2Do NOT induce vomiting unless a veterinarian or poison-control expert specifically tells you to.
- 3Call your veterinarian, the ASPCA Animal Poison Control Center (888) 426-4435, or the Pet Poison Helpline (855) 764-7661 right away.
- 4Note the amount eaten, the time, and your dog's weight and any symptoms — have this ready for the expert.
- 5Follow professional guidance and go to the nearest emergency vet if you are advised to.
A consultation fee may apply to the Pet Poison Helpline. When in doubt, contact your own veterinarian or nearest emergency clinic.
Frequently asked questions
- How much onion is dangerous for a dog?
- There is no safe amount. Toxicosis is generally associated with ingestion of roughly 0.5% of a dog's body weight in onion, but smaller amounts can still cause harm, and small dogs are at greater risk. Because all parts and all forms are toxic, treat any deliberate feeding of onion as unsafe and contact a vet or poison control if your dog eats any.
- Are cooked, powdered, or dehydrated onions safer than raw?
- No. Per VCA, dried, powdered, liquid, cooked, and raw onion are all poisonous to dogs. Cooking does not destroy the toxic compounds, and dried/powdered forms are actually more concentrated because water has been removed. Onion powder hidden in soups, gravies, baby food, broths, and seasoning blends is a common source of poisoning.
- How quickly do symptoms appear after a dog eats onion?
- Onset can be delayed. Gastrointestinal upset (vomiting, diarrhea) may appear within a day, but the more dangerous red-blood-cell destruction and anemia can take several days to become apparent. Do not wait for symptoms; if your dog has eaten onion, contact a veterinarian or pet poison helpline right away.
Sources
Related plants & foods
This page is for general educational purposes and is not a substitute for professional veterinary advice. Toxicity can vary with the amount eaten, your dog's size, and individual sensitivity. If you suspect poisoning, contact a veterinarian or poison-control hotline immediately.