Why are onions toxic to dogs?
Onions contain N-propyl disulfide, which damages red blood cells in dogs causing oxidative hemolysis. All forms of onion (raw, cooked, powdered, dehydrated) are toxic. Garlic, leeks, and chives are also part of the Allium family and pose similar risks.
Toxic thresholds
- <2 g/kg: Likely safe, but monitor
- 5 g/kg: Toxicity threshold — GI upset, potential blood cell damage
- 15+ g/kg: Severe hemolytic anemia
Symptoms may be delayed 1–5 days after ingestion.