What makes it harmful
N-propyl disulfide and thiosulfates (in all forms: raw, cooked, dried, powdered)
How much is dangerous
More than ~15–30 g of onion per kg body weight can cause problems; effects are cumulative, so small amounts regularly are also risky. Garlic is more concentrated (roughly 3–5× stronger than onion).
Symptoms to watch for
Mild / early
- • Vomiting
- • Diarrhea
- • Loss of appetite
Severe — vet urgently
- • Pale gums
- • Weakness
- • Rapid heart/breathing
- • Red/brown urine
- • Severe anemia
What to do if eaten
Contact a vet if a significant amount is eaten or any signs of anemia appear. Symptoms can be delayed 1–5 days, so don’t wait if you know a large amount was consumed.
Frequently asked questions
- Can dogs eat onion & garlic?
- Toxic — destroys red blood cells and can cause severe anemia. More than ~15–30 g of onion per kg body weight can cause problems; effects are cumulative, so small amounts regularly are also risky. Garlic is more concentrated (roughly 3–5× stronger than onion).
- What happens if a dog eats onion & garlic?
- Symptoms can include vomiting, diarrhea, loss of appetite, pale gums, weakness, and more. Severity depends on the amount and your dog’s size.
- What should I do if my dog ate onion & garlic?
- Contact a vet if a significant amount is eaten or any signs of anemia appear. Symptoms can be delayed 1–5 days, so don’t wait if you know a large amount was consumed.
Sources: Merck Veterinary Manual · Pet Poison Helpline · Project book library (cross-checked).
⚠️ For general guidance, not veterinary advice. Toxicity depends on your dog’s size, the amount eaten, and individual sensitivity. Always confirm with your vet for health decisions.