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The Daily Vet by petMD

The Daily Vet is a blog featuring veterinarians from all walks of life. Every week they will tackle entertaining, interesting, and sometimes difficult topics in the world of animal medicine – all in the hopes that their unique insights and personal experiences will help you to understand your pets.

Physiologic Urge or Taste Preference: Why Do Dogs Eat Grass?

Why does my dog eat grass? I commonly get this question in my clinical practice, for which there are multiple answers. First, it is normal for a dog to eat grass. Second, dogs do so for a variety of reasons, with each possibility needing consideration when intellectually exploring the reasons one’s canine companion has a fondness for forage.


Induction of Emesis


Plant material is highly composed of insoluble fiber that is not readily digestible and irritates/inflames the stomach wall. Blades of grass (both large and small) often accumulate in the stomach instead of appropriately moving into the small intestine.


When a particular degree of inflammation is achieved post-grass consumption, vomit ensues. Underlying illness, including Inflammatory Bowel Disease (IBD), gastrointestinal parasite infestation, metabolic disease (affecting the kidneys, liver, pancreas, etc.), or pica (see below) can stimulate the physiologic urge to vomit. Therefore, dogs can eat grass as a means of facilitating their own vomiting and for reducing nausea.


Biological/Ancestral Influence


Grass eating is a behavior exhibited by wolves and the domesticated dog (Canis familiaris). An article in the Journal of Veterinary Behavior suggests that the grass eating traits of a nursing mother can influence similar behavior in her puppies. Your dog’s mother, grandmother, and so on may be partly responsible for imparting modern-day grass eating tendencies.


Behavioral Correlation


Lack of stimulation during confinement in a particular environment, such as the back yard, can motivate a dog to eat grass or other various environmental substances. This condition, termed pica, is symptomized by the consumption of non-nutritive material. Pica leads to vomiting, diarrhea, and intestinal obstruction or perforation. This undesirable behavior can be reduced by providing a pet with behaviorally stimulating and appropriate chew toys, companionship, or (as a last resort) a cage-style muzzle.


Pica can be caused by underlying medical abnormalities, therefore veterinary examination, laboratory testing (blood/urine/fecal tests, radiographs, etc.) and dietary evaluation should be explored.


Dietary Deficiency


Veterinary behaviorists and nutritionists speculate that dogs eat grass to compensate for nutritional deficiencies. Many of my clients achieve success in reducing their dogs’ grazing by adding fresh greens and/or fibrous vegetables or fruits to the dogs’ diets. Spinach, kale, broccoli, parsley and pineapple have all yielded favorable results. Vegetables are most palatable and digestible when steamed and pureed or finely chopped before being incorporated into a dog’s meal. Additionally, dogs that eat a diet based in whole foods instead of commercially available, processed, non whole-food based dry (kibble) or canned foods tend to exhibit less foraging behavior.


As a dog owner, I discourage my dog’s regular consumption of grass. Fortunately, the occasions when Cardiff eats grass are rare. I theorize that it is because his human grade, whole food diet contains fresh vegetables and fruit (along with muscle meats, grains, etc). Additionally, Cardiff gets plenty of stimulating activity and is not permitted access to nor is confined to areas where boredom may lead to foraging.


As a veterinarian, I see grass eating dogs inadvertently ingesting toxins such as fertilizer, pesticide and other unhealthy environmental debris. Therefore, I recommend dog owners take appropriate measures to deter grass consumption during all stages of life and explore the underlying causes if their canine companions’ motivations supersede human preventative attempts.


cardiff, dr. mahaney, dog in grass, dogs eating grass, why do dogs eat grass

 Cardiff in Mondo Grass



Dr. Patrick Mahaney



Image: Dog Treat by ajball90 / via Flickr

Comments  20

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  • Dogs and Grass
    05/15/2012 11:37am

    It's a frightening thought that a critter could eat grass treated with fertilizer or grub control chemicals.

    It's interesting, though, that one can buy kitty grass so Fluffy can enjoy a snack, but I've not seen Doggy Grass marketed. Is it more natural for cats to snack on grass than it is for cats?

  • 05/17/2012 06:54am

    Thank you for your comments.
    Yes, it is frightening that our pets could consume toxins as a result of grass eating. Such is why one should not put fertilizer or pesticides on our grass. We never really know what pet may be affected by eating such substances.
    Good point regarding cat vs dog grass. I speculate that it is because most cats are indoor dwellers and their human caretakers are trying to simulate the environment they would experience outdoors by providing the chance to snack on some grass.
    Perhaps indoor growing dog grass can be the hot new trend for urban dwelling canines for 2013? Patent pending? ;-)
    Dr PM

  • 05/19/2012 04:55pm

    Our dog was at the vet this week because of hacking and gagging. Her esophagus was slightly swollen and she had an abcessed tooth that was removed. She is still eating grass once in a while and gags a little. I was told to keep her from eating the grass but that is impossible. I can't be with her 24/7 and we have five acres that she roams around in. Wondering in this is a emotional thing. Her partner, a five year old male Bassett Hound had to have both eyes removed. One on Dec. 21 and one on Feb 21 due to glacouma. He has been getting alot of attention and I wonder if she is feeling left out. We try to give her lots of attention but he had so much when we were trying to save his eyes and now we are spending time teaching him where everything is in and outside of our home.

  • 05/23/2012 06:29am

    Grass eating in small to moderate amounts (provided there are no toxins on the grass and you know the types of grass to be non-harmful) is typically acceptable.
    If the behavior seems excessive, then you must intervene to prevent overconsumption of grass. For either short or long term, prevent your dog from roaming free in the yard. Take her for walks on a flat lead so that you can ensure she doesn't eat excessive amounts of grass or other potentially hazardous substances.
    Make sure to bring up your dog's grass eating habits with your vet (again and again if needed).
    Good luck
    Dr PM
    Twitter @PatrickMahaney

  • She just likes it.
    05/15/2012 10:53pm

    The toy terrier we had as a child would occasionally eat grass and throw up, so watching Eve graze was a surprise. She is a Japanese mutt with strong Shiba inu genes, and from what I read on the internet, this is not uncommon Shiba behavior. She loves to go out in the empty lot out back, hunt grasshoppers, lizards, skinks, and eat certain grasses and the leaves of certain weeds (kind of choosey.) If there is a bunch of her favorite, she will walk around it, literally grazing. I thought at first when she started using the empty lot as her private salad bar, that she needed more veggies, but adding them to her diet hasn't changed her behavior. In fact, now it is spring and there are many soft green leaves, she grazes more than in winter. Sometimes, though, I swear she is pretending to eat grass while actually stalking a critter. If she misses her prey, she grabs a mouthful of grass, almost as if to say, "I didn't really want that grasshopper anyway, just the grass."

  • 05/17/2012 06:58am

    Great story about your pet's personal interest in grass eating.
    When you were trying to dissuade your pooch from eating grass, what vegetables were you adding? Greens?
    Those spring grasses are certainly delicious and (likely) chock full of beneficial phytonutrients that are lacking in most commercially available pet foods. The veterinary line of Standard Process supplements can make up for some of what is often missing, yet I still recommend feeding whole food based fresh/frozen veggies.
    Thank you for your comments.
    Dr PM

  • 05/17/2012 08:12am

    wow, Dr. Mahaney,
    Didn't really expect a reply, but thanks. I upped the greens, like you thought (she likes cabbage a lot.) But we feed a variety of steamed veggies, sometimes meats and scrambled egg, anyway, partly because my husband and father in law can't resist feeding her while we are eating, so I make up a plate for her to prevent them from giving her the higher calorie and highly seasoned human food. Not really into supplements because they are expensive to get here in Japan; like you stated, whole foods are good, and she is a healthy, approximately three year old. I also rotate her kibble.

  • 05/23/2012 06:33am

    I appreciate your readership, even from Japan.
    Your country is very intriguing to me as a practitioner of eastern veterinary medicine (traditional Chinese veterinary medicine = TCVM).
    I'm so pleased to hear that she eats a variety of healthy, human grade foods. Providing cooked human grade meats and cooked or raw vegetables and fruits as a means of providing calories in replacement of commercially available dry or canned foods is one of the means I see so many of my patients improve in their overall health and wellness.
    I hope to see you back again on my The Daily Vet page.
    Dr PM
    Twitter @PatrickMahaney.com

  • Yellow Root?
    05/16/2012 12:19am

    My Irish Wolfhounds have pretty constant access to grasses and plants, which they generally enjoy, although they are fed a home prepared diet that includes fruits and veggies.

    However, one of my older bitches recently displayed a behavior that I found interesting. On a walk, she suddenly went for a particular plant with an enthusiasm that surprised me, it was a plant that I later identified as Yellow Root. My husband said that an elderly friend of his who lived in the mountains of NC (we are in the Piedmont region of NC) said he used to eat a bit of this plant "for his stomach" when he found it.

    On the other side of the fence, this bitch's granddaughter (supporting what you have written) immediately begin eating plants, although in her case it was honeysuckle (which all my wolfhounds adore, often leaping up to consume). The other wolfhounds (there were several out) also began eating plants.

    The bitch who had started this, who is so intelligent she can all but read and write, had us wondering what was so great about this Yellow Root, so I confess my husband and I began sampling it as well, figuring that Tulip must know something we did not! To us, it had very little taste. But Googling it, it does have many properties that would seem to be useful.

    I do think dogs may display some "nutritional wisdom" about eating plant material, however, many dogs only have access to monoculture lawns with Kentuccky 31 or other lawn type grasses, and as you mentioned, have been chemically treated. Dogs who have access to a more varied plant biostrata may have the opportunity to display more nuanced consumption of plant material.

  • 05/17/2012 07:04am

    Interesting regarding your observations about Yelloroot. In checking it out further, I see that it contains Berberine, which is known to have many anti-microbial and even anti-cancer properties. I can't speak for its safety in pets at this juncture.
    I love the "nutritional wisdom" perspective, yet there are plenty of pets that consume material toxic to their bodies. I do tend to think that pets consume material in their environment as a result of biological urges to do so.
    I hope to see you back again on my petMD The Daily Vet page.
    Dr PM

  • eat soil
    05/16/2012 12:31pm

    My 12years cairn terrier has liver problem,also because of liver failure he had gallbladder blockage ,2years ago got remove gallbladder operation.
    he used to like eat grasses,especially when he has upset stomach,and when he is very ill and have ex-activity of bowel movement sometimes he discharge grasses in hole shape and yellow liquid as soon as(within 5min) he eat them ,but my vet. can't believe it.
    and recently he eager to eat soil.sometimes he eat dig grasses eat soil.is this also some kind of sign?like a lack of mineral,or something.

  • 05/17/2012 07:08am

    Interesting about your Cairn terrier's propensity to eat grass in association with feelings of nausea. Such is expected, but unfortunate to hear considering the underlying issue of liver failure. So, if your pet is excessively interested in eating things in your environment, definitely pursue the full workup (laboratory testing, diagnostics, etc) with your veterinarian.
    Yes, soil eating can also indicate some form of physiologic imbalance. Pre-/Probiotic therapy, whole food diets, and other nutraceuticals can help, but first rule out underlying diseases by working with your veterinarian.
    Dr PM

  • 05/19/2012 04:39am

    thank you Dr. for your comment,
    we already did his liver biopsy when he got remove gllbladder ope.2years ago,result is Chorangio hepatites.also do blood exam.every month,he has high level Alp(3500U/L)and GPT (180U/L)GOT(58U/L)and this level is continuing from 2 years ago.
    and he is having ursodesoxycholic acid for improve flew of bile.
    now we feed him with Hill's brand W/D dry food because of him abdominal problem.but I worry about that fit him or not,because I doubt his eating soil habit says he lack of some nutrition .
    do you have any suggestion in feeding him?
    mika tomita

  • 05/23/2012 06:38am

    Considering your dog's health concerns, I'd go the route of creating a home prepared diet with human grade foods by working with your veterinarian and undertaking a consultation with the UC Davis Nutritional Support Services.

    I also like cooked, frozen, human grade Lucky Dog Cuisine (www.LuckyDogCuisine.com) and cooked, dehydrated, human grade Honest Kitchen (www.HonestKitchen.com).
    Good luck,
    Dr PM

  • My dog eating grass
    05/17/2012 04:59am

    Just had my Neopolitan Mastiff to my Vets for her shots and yearly check-up. Told my Vet about her eating grass almost everyday and throwing up. My Vet seems to think that she has an upset stomach for some reason and eating the grass and throwing up makes her feel better. She told me to purchase Prevacid and give her one at nite time and that should take care of the upset stomach in the morning.

  • 05/17/2012 07:13am

    Thank you for your comments.
    While antacids can help, it's worth it to further investigate underlying reasons why this behavior is occurring by assessing food (whole food vs dry/canned food), internal organ health (through blood/urine/fecal testing, etc), and other evaluation pending your pet's response.
    Morning vomit before breakfast sounds indicative of bilious vomiting syndrome, which also tends to resolve by shortening the feeding internal (to 6-8 hrs instead of every 12 hrs or more).
    I hope to see you back again on my petMD The Daily Vet page.
    Dr PM

  • 05/18/2012 06:58am

    Not sure what you mean ? Do you mean break her feedings up to 2xs a day ? She kinda does , my boyfriend brings her breakfast every day around 6am, scrambled eggs and sausage.And then she gets her dog food about 3-4 cups(Purina One)and a half can of Alpo meat chunks, mixed with some water. She weighs 139 lbs. , my Vet thinks she should lose weight. She is spaded and is not very active. She will run around in the yard if I play frizbe or ball with her .

  • 05/23/2012 06:43am

    A dog's (and person's) body digests best when the feeding intervals are kept to every 12 hours or shorter (i.e. feeding your pet at 8 am and 8 pm, or more frequently).
    Feeding once daily or with long intervals between feedings is not the healthier option.

    Check out the foods your dog is eating on www.dogfoodadvisor.com and ask yourself if you would eat these foods yourself. If not, then why are you feeding them in the first place? You can't expect your dog to be healthy eating processed canned or dry pet grade foods. I don't feed my dog anything I would not actually eat myself.

    I'm glad to hear that you are interested in promoting weight loss in your dog. Make sure you have your vet check her for HYPOthyroidism (low functioning thyroid) to see if there is an underlying metabolic reason why she may be on the larger side.

    Good luck,
    Dr PM
    Twitter @PatrickMahaney

  • Clover and other plants
    05/17/2012 03:30pm

    My 7ish mixed breed does not eat grass, but does like to eat other types of plants, such as clover and other leafy green leaves. Although I do discourage her from foraging, I find her choices of foraging material interesting. She is on a 100% home prepared diet that does include greens such as kelp and spinach as well as other vegetables ypically including (but not limited to) green beans, celery, carrots, yellow squash, zucchinni, and an assortment of fresh fruits again typically including (but not limited to) apples, blueberries, strawberries and blackberries. She gets pure protien sources including organ meat both cooked and raw.

    She never vomits after a foraging session, and while, as I said I do discourage it, I didn't really consider it a big issue.

  • 05/23/2012 06:48am

    Thank you for your comments.
    It seems like Clover is safe for dogs according to the ASPCA's Animal Poison Control site. See:
    So, as long your dog is foraging on Clover and not other substances (that may be inadvertently consumed with the Clover), she'll likely be fine.
    I'm pleased to hear that she is eating a human grade diet with whole meats and veggies! Her body's familiarity with whole food based roughage likely contributes to her lack of vomiting post-forage.
    I hope to see you back again on my petMD The Daily Vet page.
    Thank you,
    Dr PM
    Twitter @PatrickMahaney

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