For Cats and Dogs: Hold the Onions, Please

By isak, June 3, 2009

Onions are toxic to cats and dogs causing Heinz body anemia.Onions are toxic to dogs. The toxicity is dose dependent, so the bigger the animal, the more onion need be consumed to cause a toxicity. Onion toxicity causes a Heinz body anemia. Heinz bodies are small bubble-like projections which protrude from a red blood cell and can be seen when the cells are stained. This “bubble” is a weak spot in the red blood cell and, therefore, the cell has a decreased life-span and ruptures prematurely.

If numerous red cells are affected and rupture, anemia can result. It is a form of hemolytic anemia. Onions are only one of the substances which can cause Heinz body anemia. Other substances such as Acetominophen (Tylenol) and benzocaine-containing topical preparations can also cause Heinz body anemia in the dog.

The toxic effect of the onions are the same whether the product is raw, cooked or dehydrated. The hemolytic episode usually occurs several days after onion ingestion (lowest hematocrit around day 5 post ingestion). Daily feeding of onions could have a cumulative effect due to ongoing formation of Heinz bodies versus a single exposure with a wide gap until the next exposure, allowing the bone marrow time to regenerate the prematurely destroyed red cells.

The cat is even more susceptible. Recently, Gerber began to add onion powder to all its meat baby foods. They are labeled as “better tasting”. Since baby food is often used in sick cats that are not eating (to stimulate their appetites), there was concern that the onion powder would cause a Heinz body anemia in these cats. Within a week or two of the change, there were numerous reports of Heinz body anemia in cats receiving Gerber baby food in their diets.

[I use Gerber 2nd Food Chicken or Turkey. It contains no onions.]

I strongly recommend NO ONIONS for dogs. There is no benefit and certainly the potential to cause harm.

Written by Dr. Wendy Wallner, DVM

NOTE: In moderation, garlic is safe for your dog and can help with conditions such as gas and flea prevention. It also has natural antibiotic properties.


  1. Nilgul Kirimca says:

    I just realized that the Turkey and rice had onion powder in it and my dog (shihtzu ) finished a packet …is it going to harm him?

  2. Laurie says:

    I gave my kitten the baby food chicken and rice I didn’t know it had onion powder in it what can I do to flush it out is she going to die

    • isak says:

      I’m sorry I missed your question earlier. There’s really not a lot to do after the food has been eaten, but let it make it’s way through her system. Doing it one time, may not be a problem for her, but just keep an eye on her. Gerber makes a Stage 2 Chicken and Gravy food (sometimes called “Sitter” on the label). It contains just chicken. Try that. It’s the one I use.

  3. anon says:

    Gerber second stage food chicken with rice has onion powder in it.

    • isak says:

      You want to find Second Stage Chicken and Gravy. It does not contain any spices. You do not want the kind with rice in it.

What do you think?

Leave a Reply

Your email address will not be published. Required fields are marked *