Currently the three major theoretical categories that dogs eating grass are divided are:

•   for hunger, or lack of nutrients in main diet
•   boredom
•   to induce vomiting when they are sick.

Given the above dietary theory and the fact that some dogs are sick after they eat grass would suggest that dogs do not ONLY eat grass for nutrients. They might eat grass when their diet isn’t full of all of the necessary nutrients (and trace elements) in order to gain those nutrients however if this is so, and it is instinctual, it suggests that somehow they have retained an ancestral memory of the smell or need to eat grass.

The converse theory to the nutrient theory is that grass is often included in the category of ‘PICA’ which is the technical term for the condition where a dog habitually eats things that are not food. Wild dogs have been observed eating grass (and fruits and berries when meat is not available). But they do not do so in large quantities - unless they are attempting to purge. Some other experts speculate that grass may just be the most readily available form of fibre that they need.

GRASS & DOGS BOREDOM

The boredom or exploratory theory holds most weight with puppies or young dogs. Dogs trust their highly sensitive smell sense first and a puppy will often lick or eat things that smell interesting in a trial and error mode. For instance it is said that rock eating is the most common form of pica (ref 2). This obviously becomes a problem if it evolves into compulsive behaviour. The first rule of thumb for treating boredom or many non serious psychological issues is exercise. This is obviously where dog walking comes into the picture (i.e. exercise reduces anxiety and boredom).

If grass eating is practiced by your puppy it is expected that sometimes with your intervention, they will grow out of eating inedible objects (including grass) by six months of age. Regular Ingestion of any dangerous objects (compulsive behaviour), regardless of age should be dealt with by a dog behaviourist.

DOG  PURGING

Dogs eating grass to make them sick is not consistent through all breeds. Some dogs are said to eat grass to improve digestion (ref 2). Theories abound that grass may also somehow help remove worms or solve stomach problems. One source suggests that small survey samples have found that only 10% of dogs are sick before eating grass and less than 25% of dogs vomit regularly after eating grass. (ref 1)

Another theory is that it is the texture and speed of ingestion of grass that aids a dog into throwing up. “the grass blade tickles the throat and stomach lining; this sensation, in turn, may cause the dog to vomit, especially if the grass is gulped down rather than chewed.” Ref 3

DOGS and GRASS NUTRIENTS

While many people dismiss dog eating grass for its nutrient value, I thought it useful to research what dogs may gain by eating grass. There is considerable research and support of cattle eating pasture grass rather than feedlot fed for the improvement in the end product meat quality, in particular its low fat.

The table below shows some of the typical USA analysis of grass hay:

Depending on what the animal (chicken, cow or lamb) was fed before it was turned into food for your dog, will decide whether the meat has sufficient nutrients. That said, grass does not create the elements shown in the above table, which means that if the nutrients don’t already exist in the soil that the grass is growing in, and that your dog is eating, then the grass will not have these nutrients either.

A website advocating cattle be raised on pasture grass rather than grain fed, puts a convincing argument forward that “Meat, eggs, and dairy products from pastured animals are ideal for your health. Compared with commercial products, they offer you more "good" fats, and fewer "bad" fats. They are richer in antioxidants; including vitamins E, beta-carotene, and vitamin C. Furthermore, they do not contain traces of added hormones, antibiotics or other drugs.” Ref 5

This at least suggests the value of providing pasture fed or organic meat for your dog to eat, if you can afford it.

Another remarkable fact is that “Omega-3s are most abundant in seafood and certain nuts and seeds such as flaxseeds and walnuts, but they are also found in animals raised on pasture. The reason is simple. Omega-3s are formed in the chloroplasts of green leaves and algae. Sixty percent of the fatty acids in grass are omega-3s” ref 5

CONCLUSION

It is possible that dogs eat grass for all of the above reasons: boredom, dietary and purging. If so it is one of the most regular things that they regularly come into contact with, so you might expect some kind of relationship to exist with grass besides just running on it. If they eat grass for boredom, you need to walk your dog or get a dog walker. If they eat it for diet, you potentially need to improve the quality of meat you are feeding them. If they are eating grass to purge, then they are just doing a very smart necessary thing to look after themselves, but you need to then find out what made them sick in the first place.

But of course excess eating of grass for any of these reasons should be a concern to you.

A vet can usually perform some rudimentary tests, even blood work to tell if your dog is healthy and receiving all of the basic correct nutrients in their diet. They will also ask what events or objects your dog came into contact with before they began eating grass. Like with humans, exercise, diet and interesting things to do (to ward off boredom) are just as important to your dog.

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 http://www.dogwalkersmelbourne.com.au

References

Ref 1  http://www.medicinenet.com/pets/dog-health/why_do_dogs_eat_grass.htm

Ref 2  http://www.aspcabehavior.org/articles/18/Pica-Eating-Things-That-Arent-Food.aspx

Ref 3 http://www.petmd.com/dog/wellness/evr_dg_eating_grass

Ref 4  http://www.ker.com/library/Proceedings/04/NutrientCompositionTables_p44.pdf

ref 5  http://www.eatwild.com/healthbenefits.htm