Why Does My Dog Keep Eating Grass?

Are you finding that everytime your dog goes out into the garden or on a walk they always gravitate towards the grass and they want to gobble it down with great gusto?  Have you heard that dogs only want to do this if they are unwell, have an upset tummy and they want to make themselves sick?

It is true that dogs will eat grass to make themselves vomit but usually, it is actually something less sinister than this that is motivating this action.

In this article, we hope to help you understand what might be making your dog want to act like a cow!


Grass eating in dogs is a more common pastime than you may think 

What is Pica?

Pica is a term used for an eating disorder which means that the individual is motivated to eat items that are not a normal part of the diet.  It is not just isolated to dogs and it can affect other species including humans. Whilst some Pica is explained by a dietary deficiency this is rarely the case when it comes to dogs eating grass.

Do I need to be worried?

Grass eating in dogs is not generally something to worry about.  Whilst grass is not a normal part of a dogs diet, the act of eating the grass on its own is not actually harmful, it would only be a problem if they are not eating their normal diet alongside this, if they are eating so much grass that it is becoming a concern or if they have other unusual behaviours that are occurring at the same time.

It is important to observe your dog carefully to establish any patterns or behaviours that will allow you to understand why your dog is choosing to eat grass

Is grassing eating a hard-wired instinct in dogs?

Dogs in the wild have been observed eating grass also.  There are some theories that another reason that dogs eat grass is that, in the wild, part of their natural diet would be grass eating prey.  Because they eat the whole animal which will include the little grass filled tummies they could then be getting used to this as part of their diet and that it is naturally meeting any needs for this sort of food that they have.  Again though, there are no studies to support this so it is just a theory.

There are also theories that because wild dogs are scavengers, this scavenging mentality is still present and can be stronger in some dogs more than others.  For those with a strong scavenging instinct, they will often look for other foods to eat when available and grass may be one of those.

Dogs in the wild have also been observed eating grass and there are some theories it may be an instinctual behaviour 

Are they doing it as part of a physical requirement?

It is believed that some dogs may seek out grass to help aid digestion.  There is a belief that some dogs may be eating grass due to some sort of nutritional deficiency.  Whilst this one is likely to be much less common these days given the access to such high-quality diets, it could be that your dog may have an underlying condition that is stopping your dog absorb the nutrients that they require.  From a study that was conducted it is not believed that grass eating is heavily linked to a dog trying to satisfy something lacking in their diet.

If your dog has a low fibre diet, there are some claims that dogs may seek out grass to fulfil their need for more although again, one of the most recent studies conducted on dog grass-eating habits seems to suggest this is unlikely.

There are also theories that they may seek out grass if they are suffering from some sort of parasite like intestinal worms.

Chimpanzees in the wild have been studied eating more foliage as it makes the bowel move more regularly and this can help flush any parasites out of the body more effectively.  In a recent study, more young dogs were observed eating grass. One hypothesis is because they are less able to fend off parasites this may be why they have this urge.

Of course, these are all only hypothesis.  There is no hard evidence to back this up.

Whilst there have been theories that dogs may eat grass because of some sort of nutritional deficiency this would be rare, especially given the quality of diets available these days 

Are they trying to make themselves vomit?

Often people think that a dog is eating grass because they have an upset tummy and they think that eating grass will make them vomit and give them some relief.   Despite this being quoted as the most common reason a dog may eat grass, there are no studies that support this as being the most likely reason.

It is more likely that they are eating grass for another reason and because they have eaten so much of it this has resulted in them vomiting.  Grass can be sharp and scratchy, so even a small amount can sometimes be enough to make a dog sick. It is more likely a reflex rather than the desired action.  So basically this may mean they are being sick because they ate the grass rather than eating the grass to make themselves sick!

Some dogs will be sick more easily as a result of the grass eating.  There are lots of dogs though that can eat copious amounts of grass and never experience any vomiting.

Whilst most people assume their dog is eating grass to make themselves vomit this is actually one of the least common reasons 

What a formal study actually tells us

Until recently, there have not really been any formal, large-scale studies on dog grass eating.

In 2008, however, there was a three-part study that was conducted by veterinary staff at The University of California, Davis.  This was published in the Applied Animal Behaviour Science journal.

The study began with the hypothesis that dogs did eat grass to make themselves vomit.

The first study was just with 25 vet students and their own dogs, the second was 47 clients from the teaching hospital and the third was opened up to an online survey of 1571 individuals.

From the results of the study, there was only a very low percentage of the dogs that vomited after eating grass (22% in the online survey) and only 8% of those reported their dog appearing to show signs of being ill before they actually started eating the grass.  If they were showing signs of being ill beforehand though they were more likely to vomit afterwards.

From the questions asked the study suggested that diet did not have a major impact on grass consumption and that even those with lower fibre diets did not eat more grass than those getting a higher level.

After studying the results they concluded that grass eating is generally unrelated to dogs being unwell or needing to vomit.  It is possible that if a dog has a gastrointestinal sore tummy they may seek out grass but it is not the normal reason.

Another thing that the study confirmed is that grass eating is a common activity among dogs.  68% of the online respondents confirmed that they had observed their dog eating grass on a daily or weekly basis.

The study also confirmed that dogs did not seem to seek out grass due to a nutritional need.  The dogs that had a diet with less fruit and veg were no more likely to eat grass than those with a high proportion of it present in their food.

The study did not back up claims that dogs may eat grass to get more fibre 

Do dogs just like the taste?

So, whilst the study did not examine this aspect, given the lack of evidence to support any of the other possibilities it can lead us to assume that many dogs eat grass purely because they find the taste enjoyable.

Some dogs can be very particular about the grass they eat.  You may notice that your dog tends to eat grass more frequently during the spring.  This is when the new shoots are growing so the grass is at its freshest and potentially tastiest.

There are others that may only eat certain types of grass, maybe you have a posh ornamental grass in your garden that your dog always gravitates towards.

Is it because they are bored or anxious?

There is the possibility that your dog eats grass purely because they find it stimulating and it amuses them.  It passes the time for them.

Some dogs may even eat grass to comfort themselves.  If they are an anxious dog, sometimes they can develop habits that they find self-soothing.  It is a bit like a human that bites their fingernails.

If your dog shows any other signs of boredom or nervous behaviour then you should work on treating the underlying issue rather than trying to focus on stopping them from eating the grass.  Not only will this result in a happier and more relaxed dog but they should then not feel the need to eat the grass and they will not seek out other inappropriate behaviours instead.

If your dog is showing signs of boredom, consider how long you are leaving them on their own throughout the day.  Consider a dog walker or daycare, if appropriate. Make sure they are getting enough stimulating walks and make sure you spend quality time with your dog.  

Ensure they have appropriate toys available that can help to keep them stimulated.  Our guide to safe interactive dog toys may be a good place to start.

If you have a nervous dog that exhibits other fearful behaviours then you need to work on helping your dog to feel more relaxed. Our guide on living with a fearful dog offers lots of useful guidance.

If your dog is eating grass as a result of boredom it is important to ensure that you are offering lots of other enrichment including good walks, plenty interaction and lots of suitable toys 

Be aware of the risks of products on the grass

One of the biggest concerns about a frequent grass eater is what is on the grass itself.  Often grass is treated with pesticides and herbicides. These can be very toxic to dogs if ingested.    There may also be small plants and weeds within the grass that could be a risk to the dogs. Whilst you can’t legislate for grass outside your own garden, make sure that you do not use any products that are dangerous for your dog on your own grass.

There can be other risks too.  If your dog is eating grass in a public space that is frequented by other dogs and wild animals there is a chance that, as they pull up the roots, they can pull up other parasites that may be present from the faecal matter of the other animals.  This can increase the chances of them being infected by some sort of internal parasite.

If your dog does eat grass it is important to make sure that you do not expose them to any grass treated with potentially toxic pesticides 

When should I go to the vet?

Whilst we have established that most dogs eat grass for non-sinister reasons, if your dog is showing any other unusual symptoms alongside frequent grass eating then we would always recommend visiting the vet.  There is strong anecdotal evidence that dogs with gastrointestinal problems, gastric reflux or pancreatitis tend to seek out grass to eat more frequently.

It is always worth checking in with your vet if you notice any other unusual behaviour or symptoms just to rule out any underlying condition.

Should I stop them from doing it?

If your dog does just seem to enjoy the taste of grass and they are not eating too much of it, the act in itself is not likely to be harmful.  It is not a good idea to encourage it though if they are doing it obsessively or they are in an environment where you can’t control being sure that the grass is safe to eat

Working on offering them a better alternative is the best option for helping your dog kick the habit.  Make sure you come armed with lots of super tasty treats (it has to be something the dog likes a lot more than the taste of grass) and be ready to keep a vigilant eye on your dog.

If they are off leash and will not come back when they find a tasty patch of grass, to increase your success, it would be worth considering using a long line so you can stop them from running off to find another patch.  We can also provide some useful guidance on achieving a good recall if this is a problem

Every time you see them going for a patch of grass, start walking in the other direction and ask them to come with you and when they do reward them with a super tasty treat.  With enough repetition hopefully, he will be more focused on the tasty treat than the grass. Distracting him in the environment with other rewarding activities can also work.  Take his favourite ball or another toy with you so that you can spend time playing instead of grass eating.

Some owners offer their dog a designated grass patch.  This is a box which contains safe edible grasses and sometimes herbs too and the dog is rewarded for eating from this and redirected to it whenever he tries to eat grass elsewhere.  This will not always stop your dog from eating grass elsewhere but some owners have had success with this method. If you are opting to try this make sure that the items you are using in the box are totally safe for your dog to eat.

Some people choose to give their dog a designated box that they can eat from, which they fill with safe grass and herb products

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