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Why Do Dogs and Cats Eat Grass? Three Theories

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Find out why your pet may be eating grass...

Find out why your pet may be eating grass...

As a cat or dog owner you may have noticed your pet grazing on grass, and were puzzled on the reason(s) why your pet ate, or eats, grass. Does your pet enjoy munching grass? Or, is there are a solid reason why cats and dogs are fond, though not often, of eating grass.

The answer to why cats and dogs eat grass should be straightforward in light of several studies that have been conducted in determining the reasons that motivate the animals to eat grass. However, animal behaviourists haven't agreed on the reasons put forward to explain this behaviour among cats and dogs.

In this article, we will explore three theories that have attempted to explain this phenomenon among cats and dogs:

  1. Learned habit—pica
  2. To purge out inedible contents
  3. Natural laxative

We will also consider whether humans can, and is advisable to, eat grass and then turn our attention to understanding how cows are able to digest this substance.

Dog eating grass.

Dog eating grass.

Theory 1: Learned Habit—Pica

Pica refers to the habit of an animal or human eating non-food stuff. This is particularly noticeable on dogs, and children.

The habit of eating non-food stuff is caused by a variety of factors, including anxiousness, the taste of the non-food stuff, and boredom. Puppies tend to get bored quickly if they're not involved in an activity that stimulates their high-level energy of playfulness. If a puppy is eating the grass, as stated by Natural Dog Health Remedies, "it is likely that he is bored.”

Cat nibbling grass.

Cat nibbling grass.

Theory 2: To Purge Out Inedible Contents

Cats and dogs are notorious for ingesting a variety of weird things. And, when they pounce upon their prey, they tend to eat all of it, including swallowing tiny bones and fur. These ingested substances may irritate their stomach, and cause some discomfort.

As a result, cats and dogs may resort to eating grass to induce vomiting so as to purge out inedible content(s) in their stomach.

Dogs and cats lack the enzymes responsible for breaking down the cellulose, a type of fiber in grass, which can cause them to vomit the contents of the stomach.

Some experts think dogs eat grass out of boredom.

Some experts think dogs eat grass out of boredom.

Theory 3: Natural Laxative

Animal behaviourists who base their argument in this line of thought state that the eating of grass assists in bowel movement.

As any cat owner knows, cats regularly throw up and leave lovely, wet little fur balls present around the house. But when the fur moves deep into the digestive tract, kitty needs a little help to break it down and pass it to the outer end. —PetMD

According to this theory, grass acts as a laxative in assisting in digestion, particularly when the animals have ingested substances that are difficult to pass through their digestive tract with ease.

Can Humans Eat Grass?

They can, but it is not recommended. It is possible early humans used to chew on grass, but nowadays, we are unable to digest the grass properly. This is because we lack the necessary enzymes to break down cellulose, a type of fiber found in grass. This is the reason why cats and dogs vomit after eating grass. They don’t have the enzymes which can process the fiber so that it can be used by the body.

News24 states that it is not advisable to eat grass.

Grass contains a lot of silica, which is abrasive to human teeth. Grazing animals have teeth that can re-coat their own surfaces continually, so the silica does not affect them. —News 24

Cow eating grass

Cow eating grass

How Do Cows Digest Grass?

In contrast to humans, felines, and canines, cows have a specialized digestive system that enables them to break down cellulose into finer pieces.

A cow has four digestive compartments. When it swallows grass, it is digested partially in the first and second stomach compartments then returned to the mouth. The teeth grinds the grass, which is finally broken down into finer pieces by the third and fourth compartments of the stomach.

This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.


Alianess Benny Njuguna (author) from Nairobi, Kenya on February 07, 2018:

Hahahaha, Rydog. Yesterday at evening (February 8, 2017) I saw a dog struggling to vomit as it had eaten some grass blades. I bet it was high. Hmm...cats aren't stupid as I have lived with cats since I was young. Thanks for stopping by.

Rydog on January 12, 2018:

Hi I am a dog myself, and these accusatations are simply ruff around the edges. I eat grass to get high. Thats it. Tastes like crap but sure tickles my tail. Change this video now! Or ill send my puppy friends on you!!!!!!!!!


Mr. Bork

P.S.- Cats are stupid AF!!!!!!!! #dogos

Alianess Benny Njuguna (author) from Nairobi, Kenya on October 30, 2017:

That is a perfect mix.

Jeanette Harris from 11996 Valley Falls Loop Spring Hill Florida, 34609 on October 30, 2017:

I let my cat have some grass with her cat food; she would eat lots of if I let her.