My Cat Ate Green Onion: To Worry or Not To Worry? (Solved & Explained!)

Onions on their own are easy to avoid, but we tend to like cooking them up with various meat dishes to enhance their flavors. So, what happens if your cat ate green onion that was part of a meat dish?

If your cat has eaten any amount of green onions then it is important to get them to the vet right away. Onions are safe for us, but for kitties they have an oxidative effect which can affect the amount of oxygen which your cat’s red blood cells can hold. As such, even small amounts should be considered extremely dangerous.

In this article we’re going to tell you a little more about onion toxicity and your cat so that you have the information that you need in case of accidental ingestion. It’s serious business, indeed, so read on to find out what you need to know about onions and your cat!

Why are onions toxic for cats?

Once a cat has ingested onions, the effects can literally be deadly. What happens is that oxidative damage may occur which hampers your cat’s red blood cells from being able to hold enough oxygen, which in turn means that their organs will not get enough.

What may result is a condition known as Heinz body anemia and this possibility is not just limited to green onions. Any onions may have this effect and other plants which are member of the same family, called Allium, may also cause this to occur.

The Allium family includes food plants such as leeks, onions, garlic, and chives, just to give you a few examples, and each of these is toxic for your kitty, with garlic being even worse than onions. This is because they contains thiosulfates and disulfides, both of which are quite toxic to the feline physiology.

This is vital information to know, as humans love the taste of these plants and they’re not toxic for us, so it’s easy for us to forget their presence in a number of foods and even sauces and spice mixes which we enjoy. As such, you need to keep a lookout for Alliums – they’re in more foods than you might think!

Are sauteed green onions less toxic?

No, sauteed or otherwise cooked onions are not necessarily less toxic, and in some cases they may be even more concentrated because of the cooking in this manner. Worse, they are often intermixed with gravies, and you probably already know your cat’s opinion about delicious gravies.

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It’s best to avoid even cooked onions where your cat’s health is concerned – they might actually be worse than raw, depending on how they are prepared.

Can my cat eat foods with onion powder?

Onion powder seems like it would be innocuous, but that’s only an illusion that we probably associate as safer because it’s basically ‘onion dust’ and not a whole onion. The truth of the matter, however, is that onion powder is substantially MORE dangerous for your cat.

Onions are about 89 percent water weight, so the first part of making onion powder is simple – removing the water. The onions are dehydrated by various methods and then they are reduced into flakes, which are then further reduced into a fine powder.

The resulting powder actually contains MORE onions than less, because by removing that 89 percent water content you end up with lots of smaller onions and once reduced, more onion content per volume as the powder is now considered ‘concentrated onions’.

With this in mind, foods made with onion powder should not be part of your cat’s diet – the potential for damaging their health is simply not worth the risk.

How much green onion is toxic for my kitty?

It really doesn’t take a lot of onions to make your cat anemic, with the toxic dosage considered to be a mere gram for every 5 pounds of body weight. To give you a bit more of a visual understanding of this, consider a large onion. With a large onion, you have approximately 225 to 275 grams of onion in one spot.

With a small onion, it’s around 125 grams overall, which leads us next to the toxic amount. If the toxic amount is 1 gram for every 5 grams of body weight, then that means a 10 pound kitty that eats 2 grams is in danger of becoming anemic or worse.

Now, how much is a gram of onions anyway? Well, to make it easier, think of chopped onions and let’s talk in terms of teaspoons. One teaspoon of chopped onions contains almost a whole gram, .922 grams to be specific. That means that just 2 teaspoons of onions could be potentially fatal to your cat.

This information really hits home once you know how little onion it takes to harm your furry best friend, so if your cat has gotten into some food with onions then you want to get them to the vet immediately. Their bodies are simply not designed to digest these foods – period!

What should I do if my cat eats green onions?

If your cat eats green onions then you want to get them to the vet right away. While a single, chopped bit is likely just going to give your cat an upset stomach, we all know that felines are sneaky and quick and so it’s best to assume that they’ve ingested more than you think.

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Anemia symptoms may not show for a few days or even a week, which is another important reason why you want to get the vet involved right away. Even with treatment, if the onions are in your cat’s system too long, it can take as much as 70 days to get their blood cells back to normal.

Your best bet is to visit the vet right away or if you can’t do this immediately, contact the ASPCA Poison control line at 888-426-4435. It’s toll free and they are available 24 hours a day, every day, and that even includes holidays.

Put this number in your phone and on the refrigerator – one day your it might prove to be a lifesaver!

In closing

Today we’ve taken a deep-dive into why you need to worry if your cat ate green onions. With only 1 gram per 5 pounds of your cat’s body weight being considered highly toxic, it’s important to ‘screen’ your cat’s treats and to think twice before sharing your dinner.

It’s hard to tell them ‘no’, but with foods that contain Allium plants, such as green onions, garlic, or leeks you simply cannot bend, so if you are eating these foods we recommend putting some cat-safe treats on the table so that you can hand them down as if from your plate.

Your cat will think they are getting some of your food or at least they will pretend to, just to get that treat, and everyone is going to be better off for it!