This is a difficult question to answer... because, even now, while we can guess, we're still unable to really explain why a dog eats grass! Although, one thing is for sure: we can do away with the well-established but perfectly mistaken idea that a dog eats grass to "cleanse" itself.

Fairly common behaviour in dogs... but inexplicable nonetheless

Every owner has observed their dog ingesting grass at least once in their life... and is rightfully shocked! “Why do dogs eat grass…?”, you wonder. And you'd be right in thinking that dogs do not have the physiological capacity to digest grass. And yet, they continue to eat it...

There are various reasons which may explain why dogs eat grass: stress, hunger, greed, boredom, or stomach problems. It could even be a behavioural problem. No reason is better than another; these are all possible explanations. But, to date, no reason has been found to be universal and definitive.


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Zero Effect on Parasitism

One popular myth suggests that dogs eat grass to eliminate any parasites that exist in their digestive system. However, no scientific study has shown that the ingestion of grass has any effect whatsoever on parasitism. On the contrary, dogs who eat grass can run the risk of parasitic contamination via the ingestion of parasite eggs.

Craving fibre?

It could be that your dog deliberately ingests grass to meet their need for fibre. If your dog has been exhibiting this behaviour for a while, regardless of their food intake, it may be that they have a fibre deficiency. You can adjust their fibre intake by offering them well-cooked vegetables such as green beans, carrots, or courgette. A good amount is around 50g of veg per 10/15kg of bodyweight.

Feeling peckish?

An Australian study on why dogs eat grass, published in 2007, found that eating grass was related to satiety and the time of day. The dogs observed during the study spent more time eating grass before their mealtime (especially in the morning and around noon) than after, and this behaviour decreased over the course of the afternoon. The researchers, therefore, wondered whether the grass was considered by dogs to be a food resource, a kind of "aperitif", which they then ignored when they were no longer hungry. This is the explanation for why dogs eat grass that seems most likely. In any case, there is nothing scientifically abnormal about it, neither biologically nor behaviourally, especially since dogs who eat grass have not been reported to suffer from subsequent health problems.

Does grass aid digestion?

Some researchers have wondered whether grass has useful digestive properties for dogs, that perhaps act as an emetic or laxative to facilitate better digestion.

Occasionally, dogs have been observed vomiting shortly after eating grass, but this is ultimately quite rare. If your dog starts to eat grass suddenly, particularly following a change in diet, we recommend that you consult your veterinarian to check whether the change has caused gastritis.

When a dog eats grass, it can be a sign of digestive concerns related to diet.

A Simple Precaution

Watch out for the type of grass your dog is eating: it must not have been treated with pesticides or fertilisers. Most lawn care products will indicate whether or not they are dangerous for animals.


By the Hector Kitchen medical and scientific team


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