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Can Cats Eat Onions? Vet-Reviewed Risks & Safety Guide

Dean Eby

By Dean Eby

Can Cats Eat onions

Vet approved

Dr. Luqman Javed Photo

Reviewed & Fact-Checked By

Dr. Luqman Javed

DVM (Veterinarian)

The information is current and up-to-date in accordance with the latest veterinarian research.

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It’s common for pet owners to share their food with their pets. Many pet parents treat their pets similar to children, and it can be difficult to deny anything to your beloved pet. Most foods are harmless and simply offer a tasty treat to your beloved feline. But some foods can be unhealthy for your cat, even if they’re perfectly fine for humans to consume.

Onions are one of these foods. They have loads of health benefits for you, but for your cat, onions can be a fatal food. Luckily, a tiny taste of onion shouldn’t drop your cat in its tracks, but if your cat ingests any amount of onion, they should get immediate veterinary attention. In this article, we’re going to take a look at why onions are toxic to cats and what you should do if your cat happens to eat an onion.

Why Are Onions Toxic to Cats?

Onions are toxic to cats1. Onion toxicity can also be caused by other members of the vegetable group Allium which includes garlic, chives, leek, etc. Onion poisoning can cause dehydration, an upset stomach, and is even fatal in some cases. Onions can also break down the red blood cells in your cat’s blood, causing hemolytic anemia, which can happen if your cat ingests onion in any form.

maine coon cat lying on the floor
Image Credit: Remark_Anna, Shutterstock

Can Cats Eat Any Amount of Onions?

Even in tiny doses, onions can cause numerous health problems for felines. However, the severity of the issues your cat is likely to experience is dose-dependent. If your cat eats only a small amount of onion, then its reaction may not be too severe. That said, it doesn’t take much onion to cause a major reaction and potentially deadly consequences. For this reason, it’s recommended that you seek veterinary assistance without delay.

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Are Raw or Cooked Onions Safe for Cats?

In most cases, cats will be completely uninterested in raw onions. They are naturally averse to the smell and taste of onions, so it’s not likely for your cat to eat one raw. Generally, when a cat eats an onion, it is in some other food. Whether the onion is cooked, raw, powdered, dehydrated, or in any other form, the effect is the same. It’s toxic for your cat, and any form of onion can cause the same health problems.

red-onions_Hans Braxmeier_Pixabay
Image Credit: Hans Braxmeier, Pixabay

What About Other Vegetables in the Same Genus?

Onions are part of the Allium genus of vegetables, which also includes other popular plants such as chives, garlic, and leeks. While these are delicious for humans, every plant in the allium family is toxic for your feline. If your cat eats any of these plants, the results will be similar.

Your cat can get Allium poisoning from garlic or chives just as easily as it can from eating onions. Make sure to keep all of these out of your cat’s reach to prevent any emergencies from taking place. If you decide to feed your feline food from your plate, take care to ensure that no garlic, onion, chives, or other Allium plants were used to season or flavor it.

What Should You Do if Your Cat Eats Onions?

One of the problems with cats eating onions is that the side effects can take days to kick in. It might seem like your cat is fine, but several days later, the severe symptoms might start to set in. At this point, it might already be too late.

Whenever you notice that your cat has eaten onions or other Allium plants, you should contact a vet immediately. They’ll likely want you to bring your cat in for in-person assistance unless your cat only ate a very small amount. Whatever you do, don’t try to induce vomiting. It’s easy to accidentally hurt your cat in the process, so this should be left for a professional to take care of.

cat and vet. _Maria Sbytova_Shutterstock
Image Credit: Maria Sbytova, Shutterstock

Treating a Cat That Ate Onions

When you get your cat to the vet, they will begin by assessing your feline. The treatment’s main goal would be to ascertain the extent of the onion poisoning in your cat and how they can help your cat feel better. There is no particular antidote for onion poisoning, so all treatment is purely supportive based on the signs your cat displays. That being said, you may notice your vet perform one or more of the following:

Some good options include:
  • Induce vomiting – if the onions were eaten recently
  • Administer fluid therapy
  • Perform bloodwork and other laboratory tests as needed
  • Prescribe medication depending on the signs your cat is showing
  • Monitor your cat to progress their recovery
  • Offer a prescription diet and additional supplements throughout recovery
As with all poisonings, it is best to follow your vet’s lead and advice on any care, treatment, and post-discharge instructions.

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Onions and other plants in the allium family, such as garlic and chives, are highly toxic to cats. If your cat eats any form of these plants, including raw, cooked, powdered, dehydrated, or otherwise, the results will be unpleasant at least and fatal at worst. Hopefully, you’ll never have to deal with such an issue. But if you do find that your cat has eaten allium plants, contact your veterinarian immediately for treatment.

For more information on what cats can eat, check out:

Featured Image Credit: Couleur, Pixabay

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