April 12, 2024 by The Animal Health Foundation

https://betterpet.com/are-onions-toxic-to-dogs/

Onions are one of many common human foods that are toxic to dogs. Here’s what to do if your dog eats an onion.

Written by Emily Johnson & Andrew Corti-Cervantes

— Medically reviewed by Dr. Erica Irish & Dr. Jennifer Schott

Updated March 1, 2024

Table of Contents

The essentials

Avoid onion products — Onion powder is more toxic to dogs than fresh onion and appears in a surprising number of foods.
Watch for signs of onion toxicity — Even a small amount of onion can trigger symptoms including lethargy, panting, decreased appetite, vomiting, and elevated heart rate.
Onion toxicosis can be fatal — Clinical signs often show up within 24 hours and quickly worsen, so it’s vital to get your pup to a veterinarian ASAP.

Are onions toxic to dogs?

Yes, onions are among the foods considered toxic to dogs. They contain a compound known as N-propyl disulfide , which causes oxidative damage to a dog’s red blood cells, resulting in anemia and, in extreme cases, death.

Whether raw or cooked, all parts of the onion plant are toxic to dogs, including the flesh, leaves, juice, and any processed powders. The same goes for the rest of the allium family, including chives, leeks, red, white, yellow, sweet, or green onions, and even garlic.

How much onion is toxic to dogs?

Onion poisoning gets worse the more onions a dog ingests. It’s commonly reported in pets who consume more than 0.5% of their body weight in onions, though the exact amount of onions that would be dangerous for your dog depends on factors including their weight, age, breed, and any underlying medical conditions they might already have (like diabetes, liver disease, or anemia).

👉 Certain Japanese dog breeds, including Akitas and Shiba inus, have proven especially susceptible to onion toxicosis.

Toxic levels of onion, based on size of dog

Dog size (pounds)	Breed example	Raw onion	Diced onion	Onion powder
Small (10 lbs)	Chihuahua, shih tzu, pomeranian	1/10 of a medium-sized onion	1/10 cup	1/10 tablespoon (or ⅓ teaspoon)
Medium (30 lbs)	Beagle, cocker spaniel	⅓ of a medium-sized onion	⅓ cup	⅓ tablespoon (or 1 teaspoon)
Large (60 lbs)	German shepherd, golden retriever	⅔ of a medium-sized onion	⅔ cup	⅔ tablespoon (or 2 teaspoons)

These servings are calculated using one medium-sized onion weighing half a pound as a base (the equivalent of one cup of diced onions, or one tablespoon of onion powder).

Symptoms of onion toxicity in dogs

If you think your dog may have eaten an onion or onion powder, look out for:

Lethargy. Watch for a lack of interest in playtime, walks, and other activities your pup usually loves.
Weakness. Dogs may collapse, take longer to stand, be unsteady on their feet, or experience shaky limbs.
Decreased appetite. Your pup might be uninterested in food and treats or refuse their favorite foods altogether.
Pale gums. Any gum discoloration that isn’t normal for your dog might indicate a problem.
Fainting. Watch your dog’s overall responsiveness and for any sudden losses of consciousness.
Reddish urine. Red or pink discoloration in your dog’s urine after exposure to onion is a sign that something is wrong.
Vomiting. Drooling and dry heaving are frequently seen before a dog begins vomiting, which can all be signs of a more serious health problem.
Elevated heart rate. Larger dogs have a slower heart rate (about 70 beats per minute), while smaller dogs have a faster heart rate (about 120 BPM). Dogs with noticeably rapid heart rates should be seen by a vet.
Panting. While normal for excited dogs, when combined with other symptoms, heavy panting could indicate a serious problem.

Treating onion toxicity in dogs

If your dog is exhibiting any of the above symptoms, the best thing you can do is to get them to your vet as soon as possible. Your veterinarian will do bloodwork and diagnose your dog’s condition based on their symptoms and test results. If the blood tests detect hemolytic anemia (the formation of Heinz bodies on a blood smear) after possible onion exposure, all signs point toward onion toxicity.

If your dog recently consumed onions, your vet may induce vomiting to try and remove the toxins from their body. Alternatively, they may give your dog activated charcoal to help absorb the toxins in their stomach.

Intravenous fluids can also help flush your dog’s bloodstream and rehydrate them if they’ve been vomiting. In extreme cases, your dog may require a blood transfusion or supplemental oxygen.

Safe vegetables for dogs

While onions are toxic, there are plenty of healthy and safe vegetables for dogs . These include:

Broccoli. Broccoli is high in fiber and vitamin C and low in fat but is known to cause gas when given in large amounts. It’s best used as an occasional treat.
Brussels sprouts. Loaded with nutrients and antioxidants, Brussels sprouts are healthy but can also cause gas.
Carrots. A great low-calorie snack that is high in fiber and beta-carotene (which produces vitamin A). Plus, they’re great for your dog’s teeth!
Celery. Full of vitamins A, B, and C, celery is also known to promote a healthy heart and fight cancer.
Green beans. High in fiber and low in calories, green beans are also full of healthy vitamins and minerals. When buying canned green beans, look for low-salt or no-salt options.
Peas. All types of peas are safe and healthy for dogs, including green peas, snow peas, sugar snap peas, and garden or English peas. They have several vitamins and minerals and are high in protein and fiber.

Your dog may not be able to eat onions like we can, but there are plenty of dog-safe foods out there you can use to add some variety to their regular treat regimen. Just make sure to get your vet’s okay before introducing any “people foods” into their diet.

When in doubt, remember that commercially prepared, vet-formulated dog food is always the safest option. It may be tempting to share everything we eat with our furry best friends, but keeping certain foods to ourselves is a simple, effective way to keep our pups healthy.

Frequently asked questions

Are onions bad for dogs or cats?

Plants that are members of the allium family (including garlic, shallots, leeks, and onions) are all toxic to dogs and cats. These plants contain harmful compounds known as disulfides and thiosulfinates, which cause gastroenteritis, break down the body’s red blood cells, and eventually lead to anemia. In severe cases, onion poisoning can be fatal for pets.

Will a small amount of garlic hurt my dog?

Since garlic is smaller and about five times more concentrated than onion, dogs can experience toxicity symptoms after ingesting just one clove’s worth. Still, most dogs would need to eat several times that amount to consume a lethal dose of garlic, so your dog will probably be okay if they eat a couple of tiny pieces that accidentally fall on the floor. Keep in mind that like onions, garlic is especially toxic to particular types of dogs, especially Japanese breeds.

How much onion is a toxic amount for dogs?

If your dog gets into onions, it only takes .5% of their body weight to be a toxic amount. That’s equal to one small onion for a medium-large dog.

How long does it take for onion toxicity in dogs?

Symptoms typically show up within 24 hours but can be delayed for up to seven days after the onion is ingested.

Why are onions harmful to dogs?

Onions contain N-propyl disulfide, a toxic compound that causes a breakdown of red blood cells, leading to anemia in dogs.

What happens if dogs eat onions?

Dogs who eat onions can develop a condition called hemolytic anemia. This condition breaks down a dog’s red blood cells, leaving them without enough red blood cells to function properly. It can lead to limb weakness, fainting, vomiting, pale gums, decreased appetite, and more. Severe onion poisoning in dogs can be fatal.

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