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Why do dogs and cats eat grass?
“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 is the fact that young puppies and kittens tend to be infected more heavily with worms than older animals, which usually develop some amount of immunity. Thus, young puppies (and maybe young kittens) may be more likely to eat grass because it serves a biological purpose (i.e. it gets rid of some of the worms).
I do not think we have clear-cut proof at this point in time that dogs and cats eat grass to purge themselves of intestinal parasites. However, it is an interesting theory and may very well have some merit. Further research is needed, however, before we can say that we know definitively why dogs and cats eat grass.
Should You Worry if Your Dog or Cat Eats Grass and Vomits?
In my veterinary practice, large numbers of dog owners ask about their dog and its grass eating behavior. I hear these questions less often from cat owners but do hear them occasionally. Most of these dogs and cats do not appear ill on examination. Dog owners often ask whether its okay if their dog vomits after eating grass, but I don’t have any statistics as to how many of my client’s dogs vomit after eating grass versus not vomiting. Based on the number of people of asking, I assume it to be a fairly high number so I was a little surprised to read in the survey results that a little less than one quarter of the dogs that eat grass vomited afterward.
My advice: I would not worry if your dog or cat eats grass as long as your he/she is feeling well and is not acting sick. The vomiting which occurs after eating grass should be transient. If your pet continues vomiting, I would advise contacting your veterinarian. Of course, if your pet is acting sick in any other way, you also need to contact your veterinarian.
Needless to say, if you are going to allow your pet to eat grass, the grass should not be treated with chemicals or fertilizers.
Other types of plants are another story completely. These concern me, as a veterinarian, because so many of them can be toxic and can poison a pet. I advise caution in letting your pet chew on or ingest plants. Both house plants and those in the garden can be toxic species. Even the least toxic of these plants can cause vomiting, but some of them can cause life-threatening symptoms. The most toxic of these plants can be fatal, even in small quantities.
These poisonous plants do not, of course, include plants such as cat nip and cat grass. Cat nip and cat grass are safe for almost all cats.
What About Your Dog or Cat? Does Your Dog or Cat Eat Grass? Eat Other Plants? Vomit Afterwards?
Please share your experiences with the other readers by posting a comment below. Does your dog eat grass? How often? Does he/she seem sick beforehand? Does he/she vomit afterward?
What about you cat owners? Does your cat like grass? Does he/she chew on your house or garden plants? Do you think he/she does it because of illness? Does your cat generally vomit afterwards?
I’ll share my experiences. Of my 5 cats, two of them will chew on plants if I allow it. I try very hard to keep house plants out of their reach and they do not go outdoors, so they have no access to grass. However, all five of them LOVE catnip, which, of course, is a type of herb.
Please don’t forget to tell about your pet. Scroll down to the comment box or comments link to post a reply.
Photo Credit: didbygraham/Flickr.com
About Lorie Huston, DVM
Lorie Huston is a veterinarian, pet health and pet care expert, professional writer, blogger, social media and blogging consultant, and SEO strategist.
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{ 15 comments… read them below or add one }
Actually all our dog always ate grass. Interestingly, our males would throw up after eating grass but our females would not. It is my assumption that this might have to do with the AMOUNT eaten.
Do/did our dogs eat grass because they wanted to throw up/felt sick? Sometimes they’d eat grass when we would suspect they’d feel sick. But not always.
Further, our dogs seem to be particular about the grass they’d eat. Their top preference is Timothy grass. If given a choice from a broad number of grasses, that’s what they’d eat. It seems that when the Timothy grass is available, they’ll eat it simply because the opportunity is there, whether they might feel sick or not.
When Jasmine did feel sick, she’d want to eat grass and would be more specific as to which kind. Interestingly, rather than making he sicker this would seem to make her feel better WITHOUT throwing up.
It also seems to me that, Jasmine in particular, doesn’t actually eat the grass, just nibbles on it to extract the juice.
J.D. is not a good indicator of anything, because he’ll eat anything he can get into his mouth in such an amount he can physically manage.
Given my own observations, I’d think that there could be two distinct reasons
1) the mechanical advantage in order to induce vomiting when they are not feeling well
2) the actual supplemental reason, where they are getting something that they feel is beneficial
I think animals do have good instincts to know what is good for them and know how to find it. I feel that eating grass is part of that, similarly like eating other dogs’ poop might be an attempt to supplement missing nutrient or enzyme.
Hi, Jana.
Thanks for stopping by and sharing your experiences with Jasmine and J.D. It’s interesting that they prefer Timothy grass over other varieties. I wonder why that would be. Perhaps it has something to do with the taste of the grass or perhaps there’s something about the physical makeup of the grass itself that makes it more fit to achieve their purpose, whatever that purpose might be.
It’s such a common thing, chewing on and eating grass. You’d think we would know more about why it happens and what purpose it serves, if any. But, basically, all we really have are theories right now. It’s entirely possible that there is more than one reason dogs (and cats) eat grass and the reason may vary from one situation to another.
You may also be correct about the amount eaten affecting whether vomiting occurs after ingestion or not. There’s just so much we don’t know, even about something as common-place as this.
I do believe that animals have strong instincts and that they always do things for a reason.
I found some interesting related articles
http://www.nzherald.co.nz/technology/news/article.cfm?c_id=5&objectid=10339384
http://en.wikipedia.org/wiki/Elephant_intelligence#Self_medication
http://www.biodynamic-research.net/ras/animals/a-health/
http://www.alternativevet.org/zoopharmacognosy.htm
Great resources, Jana. Thanks so much for providing them!
This is an interesting article, so thanks for that. Also thanks Jana for those links.
What I found with my pets is that my dog, who sadly passed away a few years ago, would eat grass to seemingly make himself sick. I never really noticed if he had a preference for which grass he chose for the job.
But I noticed my cat eats grass without seemingly vomiting. He may be doing it privately as we all know cats can be tetchy about personal functions. I’ve also noticed he generally eats the juicer looking grass. He also eats the catnip I give him!
So I’m not sure if this means he is just eating it because he likes it, or if he is just using it to help himself vomit but doing so privately, but it’s fascinating behaviour none the less.
It is fascinating behavior, isn’t it, Jennie? Thanks for sharing your experiences with us here.
My cats LOVE their catnip too. They don’t seem care whether it’s living or dried. One of my cats actually starts acting like he’s drunk if he has too much catnip. He gets a little “tipsy” and just keeps purring. At least he’s a “happy drunk”, or maybe I should say catnipaholic…LOL
My labs love to eat grass and rarely get sick afterwards. And Guinness, who is 12.5 yo, likes to eat dirt for some reason, so I really have to watch him. He doesn’t get sick after eating the dirt either. My dogs don’t seem to be picky about what type of grass they eat. I tend to think they eat if for the nutrients, but like you said, who knows!
That’s interesting, Julie. Thanks for sharing your experiences!
Thank you for the information. My labrador just LOVES to eat grass or any other food for that matter; He even eats the dirt, Sand and even chews pebbles! He hasn’t got sick though.
my cat shreds my plant, it has a red flower in the middle and green leaves on the outside. I dont remember the name of plant. I put the plant into another room when not at home or when going to bed. the plant leaves have dried up where he bit it and the flower also has dried up.he has not gotten sick. would it be his saliva that dried up the plant?
I don’t really know why the plant has dried up. I confess to not having a particularly green thumb, especially when it comes to house plants. However, I think you are wise to keep your cat from chewing on or eating any part of the plant, especially not knowing what type of plant it is and whether or not it may be toxic for cats.
My 7 year old cat who has had blood work done and a recent check up and her teeth cleaned, eats grass outside every time she goes out just about. Then she gets sick to her stomach and vomits. I have been feeding her wheat grass with her catfood hoping that would curve her outdoor grass appetite but she vomited grass this morning so that didn’t work. I’m considering keeping her inside completely. She does not chew on any other plants, inside or out. Maybe she is missing her catnip? I use to give this to her. hmmm.
Vomiting after eating grass is not an unsual occurrence for cats. Whether to keep your cat inside is a big decision and there are those that disagree with me, but personally I prefer to keep my cats inside just for safety reasons. Inside, they cannot fall prey to predators, annoy my neighbors or get hit by passing cars
My cats love their catnip too. There is also a type of cat grass that can be grown in planters indoors for your cat to graze on. Some people also grow catmint for their cats (and it’s beautiful in the garden too).
We have an herb garden with catnip of course, but all the cats love grass and all sometimes vomit with no ill effects. Oddly enough, they don’t like alfalfa or indoor grass. They are trained and strictly supervised outdoors in a safe garden.
My cats love their catnip too, Layla. Thanks for stopping by to share
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