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The truth from an Australian scientific study about why dog eating grass?

dog eating grassThere have been many theories about why dogs eat grass, but A group of Scientist from the School of Psychology at University of New England in Armidate NSW actually decided to test out a few of the theories of grass eating in "Canis familiaris."

The study attempted to "describe the pattern of dog eating grass during the day and the relationship between grass eating and the ingestion of food." As this is most likely a dog behavioural issue, the controlled experiment relied on studying twelve dogs over a length of time. Essentially they were offered a meal of kikuyu and couch grass three times daily for 6 days.

While it is anecdotally known that many dogs eat grass to purge themselves of something that is causing them indigestion problems, this study found no specific instance of dogs eating grass to be sick.


• dog eating grass is influenced by satiety (how full of food) and the time of day.

• Dogs spent more time eating grass before ingestion of their kibble meal than after,

• time spent eating grass decreased throughout the day.

Couch and kikuyu grasses were equally preferred by dogs.

From these observations, they concluded that dogs may consider grass mostly as a food source. They concluded this because the subjects were less likely to eat grass when they were full of food.

Before I delve more into the mechanics of this study, it should be noted that the study was only on twelve dogs over six days. The dogs were also feed kibble, which is mostly composed of grains and vegetable matter, very little meat. As dogs are carnivores, dogs fed on a raw meat diet may have a different purpose for eating grass.

It is also noted many dogs eat grass from dog parks, that will have a different vitamin and mineral composition from grass in other parks or at the owner's homes. And that grass is a living 'whole raw food' as opposed to a man made a manufactured composition that only has what the manufacturer chooses to add to the mix.

Previous research I have performed has also shown that many forms of grass contain a significant amount of Omega 3 (an essential fatty acid, essential to the health of dogs). While grass like flax contains the vegetable form of Omega 3 that is not as easily directly digested as the fish form of Omega 3, but it is better than nothing. And while some forms of kibble include Omega 3, when it is exposed to light and oxygen (ie the first time you open the packet), within a few hours the Omega 3 has severely degraded and lost its nutrition value. This is why it may be necessary for dogs to gain Omega 3 from a live food source such as grass.

As a dog walker, I have also noticed a massive increase in dogs in general eating grass around spring time. It may be the taste or the tactile value of the new shoots, but it could also be an increased level of some nutritional component in the grass at this time.

dog eating grass time taken

The study also goes onto cite previous findings of dogs eating grass studies and shows that:

Why dogs eat grass - previous studies

• Dogs have almost no capacity to digest grass (Beaver, 1981).

• grass might influence digestion by acting as an emetic - inducing vomiting (Fox, 1965; Beaver, 1981; Hart, 1985; de Baïracli Levy, 1992; Thorne,1995; Lindsay, 2001; Houpt, 2005),

• grass may act as a dog laxative (Hart,1985),

• Used for roughage (McKeown, 1996; Houpt, 2005).

A study by Sueda (2005) Also showed that dog grass eating behaviour showed " no relationship between plant eating and gender, gonadal status, breed, diet or presence of intestinal parasites."

You will probably not be amazed that a preliminary pilot study showed that dogs eat a few grams of grass per 'meal' and prefer to eat grass presented from a plant rather than cut and presented.

dog eating grass time of day


While the study is a very small one, the graphs give a good feel for what the data suggests. Dogs eat less grass when they are full of food (even kibble) and eat less grass as the day goes on.

From previous studies, unless a dog is eating grass to invoke vomiting, it is mostly seen as a nutrient source to add to its main meal. The study also shows how common grass eating is in dogs and that it is a natural activity inherited from the domestic dogs evolution from the grey wolf. Unless a dog is eating grass and vomiting after each episode, grass eating in your dog should be seen as a natural healthy act.


Article by Bruce Dwyer. If you wish to use any of this information please refer to the article as a reference and provide a link to



Grass eating patterns in the domestic dog, Canis familiaris (published 2007)

S.J. Bjone1,2, W.Y. Brown3 and I.R. Price1

University of New England, School of Psychology, Armidale, New South Wales, 2351

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