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Are onions toxic to dogs? What should you do if he eats some?

Our question this week was:

My dog ate a mini burger left in a readily accessible spot by a visitor; my worry is that the burger had a few raw onions on it. There was one piece of onion left in the take out box when I found him eating. I am aware of the danger of onions and never give him onions. Will he be okay with this small amount of onion he ate by accident?


Kathy Manley


Hi – thanks for your email. You wrote asking if onions are a problem. Dogs and cats lack the enzyme necessary to properly digest onions and ingestion of onion can result in gas, diarrhea, or severe gastrointestinal distress.

If large amounts of onion are ingested or onions are a daily part of your dog’s diet, the red blood cells may become fragile and break apart. Severe anemia and even death can occur if the dog ingests lots of onions and receives no treatment. For more information on the anemia that is caused by onion toxicity, please read Hemolytic Anemia in Dogs

If he only at a small amount on one burger – I would not anticipate that the onions be a substantial problem. Watch for any signs of vomiting or diarrhea.

Best of luck!

Dr. Debra

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