Why Do Dogs and Cats Eat Grass?

Filed Under: Dogs, Cats, Behavioral & Training, Diet & Nutrition, General Care

The age old question for pet owners has been, “Why do dogs, who are largely carnivores, and cats, who are obligate carnivores, eat grass?”  Dogs and cats receive no nutritive value from grass.  So why do they consume greens, typically grasses?  Traditionally veterinarians and behaviorists have theorized that these pets are sick and need to vomit or have some perceived dietary deficiency that perhaps the owner is unaware of.  The answer may be more fundamental:  eating grass may be a necessary inherited predisposition of dogs and cats from their wild ancestors.  

Dr. Benjamin Hart of the University of California at Davis has conducted a survey of veterinary students and pet owners in which he concludes that eating grass is a normal finding.  Reportedly up to 74% of the stomach contents in wild canines have been found to contain grass.  Dr. Hart concludes that the grass must serve a biological purpose.  He believes the plant material is necessary for the elimination of nematode parasites.  The plant material wraps around the parasites, thereby removing the nematodes from the host’s intestinal tract, and the plant material is eliminated -- a natural wormer of sorts.  Dr. Hart believes grass consumption is noticed more commonly in young animals as they are less immune to intestinal parasite infections and are carrying a heavier parasitic load.  

In cats, I personally believe that hair removal is also achieved with the consumption of plant material.   The digested plant material attaches to the swallowed hair, thereby evacuating both substances from the intestinal tract as the pet eliminates.  

Pet owners should consider grass consumption to be a normal behavior.  These pets should be checked to make sure that they are indeed parasite-free.  It is important, however, to ensure that your grazing pet be deterred from eating chemically treated lawns or any toxic plants that may be within  his or her reach.  “Cat grass”, is available commercially and offers a safe, easy to grow alternative to houseplants.


Hart, Benjamin.  “Why Do Dogs and Cats Eat Grass?” Veterinary Medicine.  December 2008.  Pp. 648-649.

Luechtefeld, Lori.  “Rules of Attraction, Natural Attractants Provide Cats and Owners with many Benefits.”  Pet Product News International.  October 2007.  Pp. 102-103.

Topics: diet, nutrition

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