Why do cats eat grass and is it a bad thing?

Lawns were made to be mowed, not meowed.

So why on earth is your cat nibbling on the green stuff outside your window—often just to throw it back up within a few minutes? Will it make them sick? And how do you make them stop?

Read on to learn why some cats like to feast on grass and what you need to do about it.

Why cats munch on grass

So why do cats like to gorge on greenery?

There are plenty of guesses floating around. A common one is that cats eat grass when they’re sick to help them throw up. But recent research finds that this may not be accurate. Instead, grass-eating felines may be reenacting the rituals of some distant ancestor.

After surveying 1,000 cat parents, researchers at UC Davis found no correlation between feline illness and eating grass. In fact, they found that only a quarter of grass-eating cats were observed to vomit afterward. Although granted, 25% is still a sizable percentage. So what’s going on, exactly?

According to the research, grass-eating may have helped some long-extinct feline forerunners expel intestinal parasites. Many other animals—chimps, for instance—are known to engage in similar behaviour for precisely this reason.

As it happens, today’s cats probably don’t suffer from the types of parasites that could be expunged by grass-eating, but they do it anyway.

Thanks, Darwin. 

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Potential benefits of your cat eating grass

So are there any actual benefits? Possibly. Let’s run through some other common theories:

• Nutrients: Grass actually contains a number of minerals, plus A, B, and C vitamins. For one thing, your kitty might be craving a snack with folic acid, a B vitamin that helps the blood carry oxygen.

• Digestion: Grass may provide roughage and serve as a natural laxative, helping your cat pass difficult bits of food like hair, bones, or feathers.

• Expelling the indigestible: One theory goes that if grass-eating doesn’t help your cat pass tough-to-digest food, it can help them vomit it up instead.

• Chlorophyll Galore-aphyll: Grass contains chlorophyll, which may have helped them fight pain or infection in the days before anti-inflammatory drugs and antibiotics could do the job instead.

Or, who knows, maybe they just like it.

Wait a minute...SHOULD my cat eat grass?

If your feline friend eats grass in small amounts, they’re unlikely to suffer any major health consequences. Many cats indulge in lawn luncheons without experiencing any adverse effects. It's true that some cats may vomit after eating grass, but as we’ve already explored, this may actually carry health benefits.

The bottom line: Common grass is generally safe for cats to eat in moderation and may actually be beneficial. There’s not always a need to limit their behaviour.

However, do keep in mind that cats are obligate carnivores, which means they need to get the vast majority of nutrients in their diet from meat-based protein. If your cat is eating so much grass that it’s limiting their appetite for more nutritious foods—or it clearly seems to be making them sick—you’ll need to limit their grass-eating.

How to stop your cat from eating grass

If your furry friend is an indoor cat through and through, it should be pretty easy to keep them from eating grass. But if your cat is used to spending a lot of time outdoors—even in a back garden or an enclosed “catio”—it may be harder to control their behaviour unless you monitor them at all times.

One thing you can do is closely examine their outdoor haunts to see if they have access to any poisonous plants; if they’ve been getting sick, grass might not be the culprit.

And not to be a downer, but it’s worth pointing out that free-ranging outdoor cats tend to have significantly shorter lifespans than indoor cats. If you think your cat is getting sick because of something they’re eating outside, you might try limiting their access to the great outdoors.

If that’s not a viable option and their grass craving is truly relentless, you can also try giving them safe alternatives to eat indoors. No cat worth their whiskers will ever turn down catnip, for instance. And there are actually some safe varieties of grass your cat can nibble on indoors—barley grass and wheatgrass, for instance.

Oh, and did we mention cat grass? Yep, that’s a thing, and countless varieties are available for purchase. You can grow it indoors, specifically for your cat. It should meet or exceed the same digestive and nutritional benefits as outdoor grass, and it’ll help you control the amount of grass your cat is eating.

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When to talk to your vet

In most cases, it won’t be necessary to actively prevent your cat from eating grass outside. But if you think their grass-eating is making them sick, you need to monitor their eating habits and change them if necessary.

If you have concerns about your cat’s peculiar eating habits, it’s always a good idea to consult your veterinarian. Your vet will advise you on how to feed your cat safe alternatives to grass without disrupting the overall nutritional content of their diet.

If your cat ever gets sick because they’ve eaten an unsafe food or they’re eating too much of a safe one, ManyPets cat insurance may help cover the cost of treatment.

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