Why my dog eats grass – The real reason revealed!

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Why does your dog eat grass?

Dogs Eating Grass - Yummy!This question has puzzled dog owners, probably for centuries.

The commonly-accepted answer is that no one really knows why dogs eat grass.

Really? Has there been no research into it?

Actually, yes there has!

The results of an investigation were published in the December 2008 edition of Veterinary Medicine by Benjamin L. Hart, DVM, PhD, DACVB. Why do dogs and cats east grass?

The dogs eating grass survey

The research was carried out by asking an initial batch of over 3,000 dog owners about their dogs’ grass-eating habits. However, this was reduced to 1,571 after several exclusion factors were applied such as owners who spent less than six hours a day with their dog – poor dogs.

Survey highlights

If you’ve ever wondered why your dog eats grass, if it’s normal or if it indicates a problem, you’ll find the results interesting and enlightening.

So let’s pitch in with the results and then take a closer look at what they mean. Here are the highlights:

  • 68% of owners said their dogs ate plants on a daily or weekly basis.
  • Only 8% said that their dogs frequently showed signs of illness beforehand.
  • 22% said their dogs regularly vomit afterward.
  • If a dog showed signs of illness before eating plants, they were more likely to be sick afterwards.
  • Of the dogs who ate plants, younger dogs ate plants more frequently than did older dogs and were less likely to appear ill beforehand or to vomit afterward.
  • There was no correlation between a dog’s normal diet and whether it ate grass.
  • Likewise, there was no indication that a dog on a low-fibre diet was more prone to eating grass than those on a high-fibre diet.

The why dogs eat grass hypothesis

Mmm... Which blade shall I eat first?The study set out to test the hypothesis that grass eating is associated with illness or a dietary deficiency, and that this is usually followed by vomiting.

The findings certainly suggest that this is not true. Generally speaking.

The percentage of dogs that display a certain type of behaviour is far from 100% so we can only say MOST dogs do such-and-such, and eating grass has such-and-such an effect on SOME dogs.

It does not necessarily explain what YOUR dog may do or why he or she does it. So lets’ take a closer look at the results and try to put them in to some context.

68% Of dogs eat grass

If your dog eats grass, they’re in the majority. Don’t worry if they don’t 🙂

Do dogs eat grass to make themselves sick?

tThis has been one of the most popular theories, although only 22% of dogs that eat grass vomit. What about the 46% of digs that eat grass but don’t vomit?

If I may use my Murphy as an example, he didn’t eat grass regularly. When he did, I tried to dissuade him by trying to get him away from the grass. Sometimes he went peaceable like, but other times he was quite fixated on eating the grass and afterwards he usually brought it up in a lump. Or two.

When I saw him in his I-really-have-to-eat-grass-now state I’d just let him get on with it, but keep an eye on him, and wait for the inevitable He seemed quite happy after that.

So perhaps some dogs eat grass because they need to be sick. At least sometimes, but obviously not all the time.

Do dogs eat grass because they feel ill?

The survey says that dogs who showed signs of illness before eating grass were more likely to be sick.

However, this was only 8%, a very small percentage, and this, too, begs a question – how do you know if your dog’s not well?

We’re not talking about major illness here, just ill enough that a quick vomit will put things right.

My question is – how do the owners know their dogs are ill before they eat grass? Some owners may say they ‘just know’ but that’s not very scientific and other than some sort of empathic connection (which I won’t rule out) I think it’s quite difficult to tell.

Murphy’s grass-eating habit

Murphy - Ah, here's a tasty bit!If Murphy was in the house he would occasionally want to go out to eat grass so he knew it was something he wanted to do. I never observed any signs of illness in him while waiting to go out, but when he started eating I could then tell if he was in his I-have-to-eat-grass mode.

So if I had been doing the survey would I report that he showed signs of illness first or not?

In addition, we cannot assume that because a dog shows signs of being ill – however you determine it – that it eats grass specifically to be sick.

Do dogs eat grass after being sick?

This was not mentioned in the article, but some owners have elsewhere reported that their dogs eat grass after being sick.

Those of a delicate disposition may want to skip the following section (although if you’re still with us after all this talk of vomit, I’m sure you’ll be fine).

Dogs eat grass to remove parasites

This is connected to a suggestion in the article that eating plants plays a part in purging intestinal parasites. The plant material passes through relatively undigested stimulating intestinal movement and, so the theory goes, carrying away any parasites.

It was also noted that younger dogs ate more grass than older dogs and it was suggested that this could be because they haven’t developed as much immunity to parasites.

This purging process goes back to the days of dogs’ wild ancestors who were more exposed to parasitic infection.

So the theory here is that eating grass is an innate tendency inherited from dogs’ ancestors the purpose of which should not, hopefully be so necessary in our modern age.

Dogs have always eaten grass

Any excuse to show a photo of a puppyDogs are genuine omnivores and waaaay back, possibly when they were wolves, they’d eat prey which was often herbivorous, consuming the contents of the prey’s stomach, too.

So essentially, eating grass is just something dogs have always done. As the survey suggests.

I can’t say that’s wrong, but by a similar line of reasoning my ancestors must have been brought up on pizza.


Dogs eat grass because of a nutritional deficiency

That dogs eat grass to make up for a nutritional deficiency is another popular theory. The dog might be trying to make up for something lacking in its diet.

Proponents argue that dogs aren’t nutritionists, so how would they know what they need?

To which I’d counter – and this is not an argument I have seen anywhere – that we sometimes feel like we need to eat a particular food. And I don’t mean pizza! Our body passes on a message that such-and-such would be good to eat now. And, again, that doesn’t refer to cream cakes, either.

Eat what your body tells you to

(This is a short but analogous excursion into a condition I hope you’re not often afflicted with.)

She'll be sorry in the morningYou may, or may not, have a favourite hangover cure. Mine is drinking milk and eating bread buns and cheese. That’s what my body tells me to do.

Another example is my cousin who had been a vegetarian for decades, and then started eating fish. I asked her why and she said her body told her it was what she needed.

Similarly, a dog’s body might be telling it to eat grass, possibly for nutritional reasons..

(Normal service is now being resumed.)

Dog nutrition

Bobe? Grass? Bone? Grass? Tough choice!If a dog eats grass, dog nutritionists often suggest changing their diet.

The survey said there is no indication that a high- or low-fibre diet or any kind of diet in fact, had a bearing on whether or not a dog ate grass.

Of course, that doesn’t mean that any particular dog’s body is NOT telling it to eat grass.

Some dog owners have reported that putting their dogs on a high-fibre diet reduced, if not totally cured, their grazing habits. So that’s something you might want to consider but do consult with your vet about your dog’s diet first.

Dogs eating grass is normal

But before you look to change your dog’s diet, do bear in mind that the survey suggests eating grass is normal, at least for 68% of dogs.

Digesting grass

Grass - Yay!When Murphy was not in his I-have-to-eat-grass-now mode, he’d still occasionally nibble on it. Many dogs do this and aren’t sick afterwards.

However, grass is not readily digested by dogs which feeds the idea – sorry! – that it aids their digestion. It’s part of the high-fibre argument.

But it brings with it other problems.

All grass must pass through the…

Grass mostly passes straight through a dog.

After eating grass and after having a poo, it’s not uncommon to see a blade sticking out of their rear! This, understandably, can be uncomfortable.

Murphy would sometimes strain to have another poo to shift it or try to bite it out but anatomically he found that quite difficult.

The humane thing to do is to pull it out for them. In the woods I used to grab a large leaf but elsewhere a tissue is just fine and easily popped into a poo bag. Your dog will thank you. Really they will.

Dogs like grassGrass - I love you!

So innate ancestrally inherent eating habits apart, dogs still have strange tastes – at least from our point of view – and it could be that dogs eat grass simply because they like it!

There’s a radical thought!

Dogs are greedy eaters

Most dogs are naturally greedy and will eat anything offered to them – and take anything else they can get their paws on if you don’t keep it well out of their way.

So why not add grass to the menu? Many dogs eat grass and are not sick – 78%, in fact.

Grass binge eating?

Is it possible that the dogs who are sick are sick because the binge on it – a bit like us eating too many cream cakes?

If that is the case there won’t be much you can do to stop them – don’t you dare try to take my cakes away! – but, again, you could try a higher-fibre diet and see if that helps.

Dog get bored, too

I'm bored, bored, bored, bored, bored!There are other possible causes, too, which I don’t believe were specifically looked at in the survey.

Another theory about why dogs eat grass says that they could be bored.

If you frequently put them in the back garden and there are no balls being thrown or small furry animals to chase, once they’ve exhausted smelling all the smells, they may well be bored.

If this is the case, you may see them mope about for a while before tackling the green stuff.

This is a different behaviour to a dog who begs to go out and immediately starts eating grass.

The bored dog solution

I'm not bored! I'm not bored!The solution is obvious. If you’ve been a bit lax with the exercise routine, give your dog more exercise. Play with him or her more, throw a ball or Frisbee.

Boredom can also be caused by lack of mental stimulation. Try giving your dog a chew or a dog puzzle. But don’t do that as an alternative to exercise.

Don’t let your dog eat toxic grass or plants

Can I eat this?This is the final consideration.

Although eating grass has no detrimental effect on dogs, you do need to take care where they do their grazing.

Grass itself is not harmful but many lawns and fields are sprayed with chemicals which can be toxic. Make sure your lawn and grassed areas are safe.

Also, some dogs eat plants as well as grass. The two were not differentiated in the survey.

There are a phenomenal number of plants that are toxic to dogs so the safest advice is not to let them eat any at all.Dogs Trust list of poisonous plants

If you do catch them eating a plant, check to see what it is.

Also, do check all the plants in your garden and house – yes, your house, too – for potentially poisonous ones. There are more than you may think.

Here’s a nine-page list in PDF format produced by the Dogs Trust: Dogs Trust List of Poisonous Plants, Garden and Household Substances

Here’s a list produced by the Kennel Club: House and garden plants poisonous to dogs

And here’s a list of the Top Ten Offenders: Top 10 Plants Poisonous to Pets

Why do dogs eat grass? – The bottom line

First of all, realise that eating grass is normal. But also realise that different dogs may eat grass for different reasons.

Secondly, be aware of the reasons why your dog may be eating grass, particularly if they suddenly start being sick or eating grass more often than usual. If you’re concerned, see your vet.

Finally, if your dog does eat grass, make sure they aren’t anywhere near potentially poisonous plants or grass that might have been chemically treated.

Other than happy – happy grazing!

If you have any questions about this article or any thoughts on the subject, please leave a Comment below and I’ll reply as soon as possible.

You may also be interested in these features:

Can dogs eat bacon? – Or other pork food?

Should dogs eat ice cream? – What are the alternatives

How to stop a dog from chewing his bed

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4 comments on “Why my dog eats grass – The real reason revealed!

  1. Hi, good quirky but interesting post, I always thought they ate grass to be sick but not so sure now. Thank you very good

    • Thanks, Steve.

      I think there are several reasons why dogs eat grass. Although some – 22% – are sick after eating it, I don’t think that’s primarily why they do it. More research needed! 🙂

  2. Hi, I thought this was a great topic but I read it over a few times and, I honestly couldn’t see where your hangover cure and body talk played into the reason for dogs eating grass. I still thought the topic was great but, I’d take out the cure for a hangover unless it’s what dogs experience when they eat grass. Or were you trying to say you felt like a dog after a hangover?

    • 🙂 Thanks, Jaye.

      Perhaps the point was a little drawn-out but I was trying to draw an analogy.

      Essentially, I’m saying that sometimes our body tells us what to eat – my hangover food and my cousin saying her body told her to eat fish. I’m suggesting that perhaps dogs’ bodies are telling them to eat grass.

      Hope that helps.

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