s by LORIE HUSTON, DVM
“Why does my dog eat grass?” “My cat loves to chew on the leaves of my plants. Why does he do that?” These are questions that several readers have asked me in one form or another. So, I’m going to try to answer them for you.
Why do Dogs and Cats Eat Grass?
Unfortunately, the short answer to that question is that we do not really know. There are lots of theories. Some of the most common are:
§ dogs and cats eat grass because they have an upset stomach or intestinal tract and need to make themselves vomit
§ dogs and cats eat grass because they have a dietary deficiency
§ dogs and cats eat grass because it helps them purge intestinal parasites from their gastrointestinal tract
Do Dogs and Cats Eat Grass Because They are Sick?
Dr. Karen Sueda, Dr. Kelly Cliff and Dr. Benjamin Hart have completed several surveys which seek to examine this question. (Source: “Why do dogs and cats eat grass?”, Dr. Benjamin Hart,FIRSTLINE, December 1, 2009). Let’s look more closely.
According to the surveys, roughly two out every three pet owners said their dogs eat plants daily or weekly. Grass is apparently the most common plant which dogs eat. Other surveys have indicated that cats may ingest plants other than grass more frequently but eating grass does not seem to be as common in cats as in dogs. So, it would appear that the majority of dogs eat grass on a regular basis and cats also sometimes engage in this behavior but may prefer other plant varieties.
Very few dog owners (8% in one large survey conducted online) said that their dog frequently appeared to be sick before eating grass. So, even though illness may be responsible for the habit in a few dogs, it does not appear that disease is the cause for most grass-eating dogs. The same appears to be true in cats.
Is it Normal for My Dog or Cat to Vomit After Eating Grass?
Nearly 1/4 of dog owners said their dog vomits after eating grass. Preliminary data in cats indicates that they also vomit only occasionally after eating grass. So, in answer to the question, vomiting can occur after a pet eats grass but does not always occur.
Younger Dogs Eat Grass More Frequently Than Older Dogs
According to the online survey, which also gathered data on the age, sex, sexual status (intact vs. neutered) and breed, younger dogs were found to ingest grass more often than more mature dogs. Younger dogs were also less likely to appear sick prior to eating grass or to vomit afterwards. Similar data, to my knowledge, is not yet available for cats.
It is suggested that this age discrepancy may provide proof of the fact that dogs (and possibly cats) eat grass as a means of purging worms and other parasites from their gastrointestinal tract. The theory put forth by Dr. Hart and his group is that “the plant material passes through the intestinal tract, increasing intestinal motility and wrapping around worms and thereby purging the tract of intestinal nematodes”. (Nematodes are a type of worm.) Further support for this theory.... read more