Sharing food with your dog can be a fun bonding moment between pet parents and their beloved companions. While this is a great experience, safety is of the utmost importance. There are many foods that humans can eat that dogs cannot ingest due to health reasons.

You may have cooked yourself a delicious meal that included a side of onion rings. However, before you toss that last onion to your pup, you might want to reconsider.

Onions are not a safe food for dogs to eat. If your pup consumes onions or onion products, they can become seriously ill.

Why Are Onions Toxic?

Why Are Onions Toxic

You may be wondering “why are onions bad for dogs?” All types of onions are toxic for dogs to consume, whether red, yellow, white, green, or another type. This is because onions are part of the Allium species and contain organosulfur compounds.

The compound is called N-propyl disulfide, which adheres to and damages red blood cells when metabolized by a dog’s digestive system. The loss of red blood cells results in oxidative hemolysis, which negatively affects the ability of the blood in your dog’s body to carry oxygen. Red blood cells will rupture and consequently be destroyed.

This causes mild to severe anemia in your pup. While mild anemia can resolve on its own with proper care, severe anemia can require a blood transfusion.

What Amount Is Needed For Onions To Be Toxic?

Ideally, your dog should never eat onions or products that contain onions. While one onion ring may not hurt your dog, the compounds can stay in your pup’s system and build up over time.

If you are feeding your four-legged companion one onion ring daily, there is a good chance that they will develop onion poisoning over time due to the build-up of the organosulfur compounds in their body.

Veterinarians consider a toxic onion dose to be around .5% of your pup’s body weight. This is estimated to be about 15 to 30 grams of onion per kilogram of your dog’s weight.

Therefore, only a quarter cup of onions is needed to produce a toxic reaction in dogs that weigh around 20 pounds. The onion ring simply is not worth it.



If you suspect your dog has onion poisoning from consuming onions, there are many signs you should be on the lookout for. Initially, your dog may salivate excessively and have some irritation around its mouth.

The onions may cause gastrointestinal upset, which can lead to vomiting and/or diarrhea. More severe symptoms of onion poisoning are as follows:

Lethargy and weakness are typical signs of anemia. Other symptoms to keep an eye out for are rapid heart rate and excessive panting. You can also check if their gums are pale or blue in color, which is a classic sign of anemia.

In serious cases, your pup may collapse or faint and become unresponsive. Symptoms of onion poisoning should never be ignored. Severe symptoms warrant an immediate vet visit, as anemia can become deadly.

What To Do If Your Dog Eats Onions?

Dog Eats Onions

If your dog gets a hold of some onions or your side of onion rings, try not to panic. Remove any leftover onions from your dog’s reach and clean your dog’s face and mouth. Always ensure that all of the onions and onion products are put away in a safe and secure place so that your dog cannot get to them.

If you are able to, attempt to induce vomiting so that your dog can expel as much of the onion as possible. Give your pup some activated charcoal to help reduce compound absorption during digestion.

Once you have your pup settled and given plenty of freshwaters, call the vet. The vet will be able to walk you through any extra steps you can take as well as the signs you should be looking for. Keep your pup well-hydrated and comfortable, along with feeding them food that is low in oxidants.

If your pup’s symptoms get worse or your dog has consumed a large number of onions, take them to the vet to be seen. Severe anemia requires medical attention, such as blood transfusions, to be properly treated. Do not take it lightly as it needs treatment ASAP!


Onions are a no-go food when it comes to dogs. There is never an okay amount of onions to give to your pup. While smaller amounts of onions may have little to no adverse effects, harmful compounds can build up in a dog’s body.

Onion poisoning causes anemia in dogs. The symptoms vary depending on how severe the anemia is. In serious cases, dogs can become unresponsive and need immediate veterinary care.

Think twice before feeding that onion ring to your dog. Toss them an unsalted french fry instead or another dog-safe treat.

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