Are onions poisonous to dogs?

Onions, garlic, chives and leeks (Allium species):

When onions and garlic are ingested in large or chronic amounts, it results in Heinz body formation and anemia. Cats are more sensitive than dogs to Allium toxicosis. Clinical signs are generally secondary to the anemia, with resultant weakness, lethargy and pale mucous membranes. Avoid using onion or garlic powder chronically in pet food, and make sure your pet doesn’t ingest large amounts!

What it’s in:

The small amount of garlic sometimes found in dog treats is unlikely to be harmful to dogs. However, if cats or dogs ingest a tasty pan of sautéed onions, garlic, or leeks, poisoning may result. The ingestion of large numbers of garlic pills or powder may also cause poisoning. Garlic was once thought of as a “home remedy” for flea infestations; however, it has been shown to be ineffective and is not recommended by Pet Poison Helpline®.

Threat to pets:

These vegetables can cause red blood cell destruction (specifically, Heinz body formation) and result in anemia.


Onion/garlic smell on breath, lethargy, pale mucus membranes (due to anemia), tachypnea (elevated respiratory rate), tachycardia (elevated heart rate), vomiting, and a reduced appetite. Rarely, hypoglycemia (low blood sugar).


Induce vomiting and give activated charcoal to decontaminate. Check a PCV (packed cell volume) or blood smears daily to evaluate anemia, blood transfusions if severe anemia.


Excellent with early intervention and appropriate care.