Onion Toxicity in Dogs

A Food Danger Many Dog Owners Don't Know About

Jan 10, 2008 Joy Butler

Feeding dogs pizza, hamburger, spaghetti, and other table scraps with onion can cause Heinz body hemolytic anemia.

Most people know about the dangers of chocolate to dogs but many people have never heard of onion toxicity in pets. They’ve perhaps fed their dog foods containing onion such as leftover pizza, hamburger, or gravy and nothing happened. A small amount may not cause a problem since onion toxicity is dose dependent. However, onions in any form (raw, cooked, dehydrated or powdered in a seasoning) can create a life-threatening form of hemolytic anemia in dogs.

What Happens in Onion Toxicity?

Red blood cells carry a protein, hemoglobin, which delivers oxygen to the tissues and organs. Onions contain a substance called thiosulphate which dogs (and cats) lack the enzyme to properly digest. Thiosulphate causes oxidation of hemoglobin in canine red blood cells, which then forms clumps, weakening the cell membranes. These clumps, called Heinz bodies, protrude from the cell and eventually cause rupture, shortening the life span of the cell. When enough red cells are destroyed, anemia occurs and the body is starved for oxygen. Garlic also contains thiosulphate but in smaller amounts.

A significant decrease in red blood cells can cause many problems including heart failure. The number of cells destroyed usually depends on the amount of onion eaten. However, some dogs can develop severe reactions even after eating very little onion. Small amounts of onion fed over a period of time can create illness just as a one-time dose can, due to the gradual build-up of Heinz bodies. On the other hand, some minor cases of onion toxicity may go undetected due to damage of fewer red blood cells. Symptoms sometimes take several days to manifest.

Symptoms of Onion Toxicity

Weakness and lethargy

Vomiting

Diarrhea

Difficulty breathing

Pale or bluish gums

Bloody urine

Jaundice

Decreased appetite

Increased heart rate

Severe toxicity can be fatal

Treatment of Onion Toxicity

If ingestion was recent, decontamination and intravenous fluids are traditional treatment. If anemia is severe, a lengthy hospital stay and a blood transfusion may be necessary.

Preventing Onion Toxicity

Onions are common in many human foods, including some baby foods, hush puppies, sandwich meats, canned spaghetti, gravies, fast foods, and many prepared meals. Check ingredients carefully in any table food before treating your dog to a snack. Avoid adding onions in any form to homemade dog food recipes. Make sure garbage is kept covered and away from dogs.

Sources:

Wendy Wallner, DVM JLHWeb.net

Sophia Yin, DVM SFGate.com

Dr. Susan Barrett Dog Central

The copyright of the article Onion Toxicity in Dogs in Dogs is owned by Joy Butler. Permission to republish Onion Toxicity in Dogs in print or online must be granted by the author in writing.

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Comments

Aug 15, 2008 8:23 AM

Guest :

My labrador retriever almost died from eating a warehouse sized bottle of freeze dried onion flakes. I had called my vet and they said he'd have diarrhea but he'd be just fine. Do not accept such answers. My dog almost died, had five days in intesive care and it cost me $2,000. Thankfully, I got him back alive and healthy.

Aug 18, 2008 12:37 PM

Guest :

FYI -- Pedigree brand canned dog food contains onion powder! I called the company; the customer care rep I spoke to seemed unconcerned (of course). I suggested she might have their vets/nutritionists take another look at the issue. I will be returning the food to the store where I bought it.

Sep 24, 2008 10:36 AM

Guest :

Hi,

I have a book about natural dog health, nutrition, medicine... In this book the doctor says that to repel fleas add pure garlic and brewers yeast to your dogs food. In this article you mention that Garlic also contains thiosulphate? Have you ever heard of this mixture to repel fleas, is it safe? Do you have any other recipes that might help repel fleas because I don't want to give my dog flea medication, it's too full of chemicals. What I find strange is the author of this book was even on Oprah so how can Garlic be so dangerous if he is recommending this? He even mentions garlic being good for other things??

Thanks, Karen

Nov 13, 2008 6:11 AM

Guest :

BEWARE! SOME BRANDS OF CHICKEN STOCK/CHICKEN BROTH CONTAIN A LOT OF ONION POWDER! I have a convalescing dog that is on a bland diet of pasta and/or rice cooked in broth. Bought organic range-chicken broth, and realized that the ingredients listed onion powder... had to throw the whole pot of pasta away.

Jan 15, 2009 10:41 PM

Guest :

to the person about the pedigree food, they know what they're doing, onion is in many dog foods, just in tiny amounts, also garlic barely has any in to the next person and to the last person it just depends how much stock there is, the first person's dog survived a massive amount of onion (thankfully!), a tiny dose is fine

Feb 27, 2009 8:31 AM

Guest :

Should I consult a vet? Re: Human bisto/oxo gravy added to dog food.
I am looking after a friend's dog for the next 2 months.
I observed a strong dislike for the Chappie/biscuit and mixer blend, with the dog leaving the food untouched. When tried alongside other foods (I tried pedigree, raw and cooked meats and fish) the dog ate these whilst leaving most of the original food untouched. The owner recommended adding bisto or oxo gravy to make the dogfood appealing and says they have been doing this for some months and the dog eats it without fuss.
These food items have a high salt content and contain onion powder.
Should I take the dog for tests for anaemia, given that it has been unknowingly fed daily doses of onion powder for some time?
I also know there was some concern about the dog's loss of weight. Could this be a contributory factor?
Thanks,
Zapo

Mar 1, 2009 7:08 PM

Guest :

I am caring for my son's friend's dog, a siberian husky 9 month old. I have never cared for a dog. How many times a day do we let her out. Is she fed only one meal a day. How about fruit and vegetales. she seems to love baby carrots.

7 Comments