You don’t want to risk your dog suffering from anemia.

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golden retriever in front of red onions repeating on a light blue background
Credit: Hans Surfer / Science Photo Library / Getty

Dogs can eat onions in small amounts—but that doesn't mean they should. In fact, it's best just to keep the ogrey veggies away from your dog at all times.

That's because onions, when dogs eat too much of them, can make pups incredibly sick, says Ahna Brutlag, DVM, MS, DABT, DABVT and director of veterinary services at Pet Poison Helpline & SafetyCall International.

"There's always a point at which the dose becomes a problem," she tells Daily Paws. 

The symptoms can even be life threatening. So make sure to keep them away from your counter-surfing dogs. They don't want to end up like one of Brutlag's cases: a Labrador retriever who ate some garlic and "quite a few of the onions" before their owner could use the ingredients to make salsa. The poor pup became incredibly sick, needing a blood transfusion, before recovering. 

So, yeah, don't mess with onions. (If your dog did eat onions, scroll down to the "What Should I Do?" section.)

Why Onions Are Bad for Dogs

In the simplest terms, onions hold sulfur-containing oxides, Brutlag says. Those are dangerous because they destroy dogs' red blood cells, which bodies need to deliver oxygen to the organs. 

"The red blood cell is destroyed," Brutlag says. "It effectively bursts, and when dogs get into toxic amounts of onions and garlic, it causes life-threatening anemia because they don't have enough red blood cells to carry the oxygen that they need."

Additionally, they're probably unfamiliar enough to your dog's digestive system to cause vomiting and diarrhea, Brutlag says.

Can Dogs Eat Cooked Onions?

No. Don't let your dog eat anything with onions in it. Cooking or freeze-drying onions doesn't make them any less toxic, Brutlag says. Same goes for onion powder, which actually might be worse because it doesn't have any water in it, so it's more concentrated.

Now, if your dog only eats a small amount of onions—cooked or otherwise—he might be OK. Generally, dogs who consume under .25 of an ounce per pound of body weight will be fine, Brutlag says. That's why big dogs can get away with eating some onion while veterinarians will be more concerned with small dogs eating some.

"We always worry about smaller dogs more just because they all have their small body size," she says.

Symptoms of Onion Toxicity in Dogs

Brutlag says these can span over the course of several days, so you'll want to closely watch your dog if you know he ate onions. Here are some of the symptoms:

  • Vomiting
  • Diarrhea
  • Lethargy
  • Exercise intolerance
  • Paleness in the gums (dogs' gums should be pink, not light pink or even white)

Those final three symptoms could be signs of anemia—your dog's organs not getting enough oxygen. It's time to call your veterinarian, though you should do that as soon as you know your dog's eaten onions.

My Dog Ate Onions. What Should I Do?

Call your vet. If you can't reach them right away, call Brutlag's colleagues at the Pet Poison Hotline at (855) 764-7661. They're available 24/7 and can advise you on how to treat your dog. 

They'll ask the general questions about your dog—size, breed, underlying medical conditions—first. If you can do it safely, they might advise you to induce vomiting

"Assuming they vomit up most of the onion, we probably don't have much to worry about," Brutlag says.

Not all dogs should vomit at home, though. Brachycephalic dogs can sometimes inhale the vomit, and that's obviously unsafe. A veterinarian can safely get them to vomit the onion. 

Post-vomiting, a vet might also prescribe an activated charcoal, which can bind to the onion in your dog's stomach, preventing the toxicity from spreading into the body, Brutlag says. After that, a vet should check your dog's red blood cell count to make sure the cells aren't abnormal.

If they're damaged, more treatment is required. That can include a normal IV drip, a sugar IV drip, and then other, basic supportive care, like making sure the dog is getting enough antioxidants, Brutlag says.

For dogs who still have a low red blood cell count, a blood transfusion might be the only thing left that can stave off the anemia. Thankfully, there's plenty you and your vet can do before you get to that point.

"The good news is if you catch it early and act quickly, the vast majority of these animals have excellent prognoses," Brutlag says.       

Safe Vegetables to Feed Your Dog

Good news! If you and your dog are on a health kick, there's plenty of veggies you can share with your pup. Here are our favorites:

Enjoy!