Why Do Dogs Eat Grass? Causes and Prevention Tips · The Wildest

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Why Do Dogs Eat Grass?

Your pup is literally vegging out—when it’s no big deal and when to worry.

by Daniela Lopez and Dr. Amy Fox, DVM
Updated June 13, 2024
Kurzhaar's dog eats grass, oats, happy puppy playing in the meadow
Daria Photostock / Shutterstock

Once the weather is nice, and you’re spending time outside with your pup, everyone’s happy. Everyone (read: your dog) is also eating grass. Why? There are many theories as to why dogs eat grass, including instinctual behavior, dietary deficiency, or possibly digestive upset.

Many of these theories are unproven and in most cases, eating grass can be a normal behavior for dogs. But while occasional grass eating is generally considered normal, persistent or excessive consumption may warrant a closer look at the dog's overall health.

The truth is that no one knows for sure. There have been very few scientific studies designed to answer this question, so most of what we know is based on theories and observations. One of the main reasons we suspect dogs eat grass is because it is an innate behavior.

This is based on observations that their wild ancestors, wolves, also eat grass routinely. It may be a way for them to obtain fiber and/or to help remove intestinal parasites as it passes through their digestive tract. Or, it may help create a feeling of fullness when they are hungry. One early study showed that dogs tend to eat more grass early in the day and especially before feedings.  

Another theory is that dogs eat grass to soothe different kinds of digestive upset, such as nausea, vomiting, or diarrhea. More research is needed to dive into whether any forms of digestive upset lead to an increase in grass eating but no consistent links have been found thus far. 

Is eating grass a sign of sickness?

Probably not. Based on the studies to-date and general observations, there is not a consistent link between illness and eating grass. And while many pet parents consider illness to be the most likely reason dogs eat grass, studies don’t support this theory. In one study, only eight percent of the respondents reported seeing signs of illness before their dog ate grass, and of that group, only 22 percent reported that their pups actually vomited after doing so.

In another study, researchers who compared grass-eating behaviors of dogs with mild gastrointestinal disturbances to those without any GI signs concluded that a healthy dog was actually more likely to eat grass than one with diarrhea, specifically. This study did not compare their findings to other kinds of digestive upset, such as nausea and/or vomiting, so the results concluded only that diarrhea was not a motivator for dogs to eat grass.

Or, is eating grass normal dog behavior?

For most dogs, eating grass is normal stuff. It’s possible that pups eat grass to pass the time or to aid in digestion, or because — here’s a shocker — the grass tastes good. It’s likely that eating grass is a natural behavior for dogs, one passed down from their wild ancestors, wolves. And in reality, no one knows for sure why they do it, or if they all do it for the same reason.

Grass may also provide dogs with a source of fiber which has many health benefits. Fiber is technically a form of carbohydrate that is not broken down during digestion. In this manner, it adds bulk to the stool which can help to prevent constipation, increase feelings of fullness without added calories, and some fiber also provides nutrients to the microbiome. Some pups take their grass-eating too far, though, and if they are obsessively eating large amounts of grass it may be worth a deeper investigation. 

Reasons why dogs eat grass

There are numerous theories as to why dogs eat grass. In nearly all cases, they are just that: theories. These are unproven but based on observations or specific case studies. And it may be that different dogs eat grass for different reasons, so more than one possibility may be true. Here are some common reasons we think they eat grass:

1. Upset stomach

This has always been a common myth to explain why dogs eat grass. Many people believe that they eat grass to soothe their stomachs, or as a way to induce vomiting. This has not proven true in research studies.

Multiple studies have found that dogs eating grass do not show any signs of digestive upset, and only a small handful of dogs will vomit after eating grass. More research is needed to further investigate; however, so far this does not seem to be true for most dogs.

2. Boredom

This is another common theory that dogs eat grass or other non-food items out of boredom. There are no studies that have focused on this particular theory for grass-eating, but there are general studies that show some dogs develop behavior issues related to eating non-food items when they are bored or understimulated. 

3. Hunger

One early study noted that dogs tend to eat more grass in the beginning of the day and especially prior to feedings. This led to the theory that they may be eating grass to satiate themselves and create feelings of fullness.

4. Anxiety

Dogs with certain behavioral disorders including anxiety and compulsive behaviors sometimes eat non-food items. This is known as pica. It can also happen due to an underlying medical condition so any cases of suspected Pica should be fully evaluated by a vet. 

5. Nutritional deficiency

Some theories have suggested that dogs eat grass as a source of fiber or due to other deficiencies. Nutritional deficiencies can be a cause for pica in general, so a dog that is eating large amounts of non-food items should have a thorough medical work-up. 

Why is my dog eating eating grass and throwing up?

There is not one definitive answer to this question but lots of possibilities. First, it is interesting to note that research studies have not shown a link between eating grass and vomiting. The majority of dogs in these studies did not vomit after eating grass so we don’t think that eating grass routinely causes them to vomit.

We also do not have any scientific proof that dogs who are already feeling sick and have digestive upset will seek out grass more than healthy dogs. Knowing this, it is hard to make a definitive link between eating grass and vomiting. It is possible that some dogs eat grass whether they are sick or not and so it is pure coincidence that sometimes they vomit after eating grass.

In other cases, if they are mostly eating grass early in the day, especially prior to a meal, they may be vomiting due to a condition known as bilious vomiting syndrome. These pups tend to vomit when their stomach is empty for too long. 

The best way to determine why your dog is eating grass is to take note of the pattern; is it usually happening around a certain time of day? How does it relate to their meal times? Does it coincide with periods when they are alone more versus times when you are home? These factors can help drill down on what may be motivating them to eat grass and can help your vet give you more answers.

When it comes to why a dog vomits, there are many possible causes. If your dog is vomiting frequently or has other signs of illness such as decreased appetite, low energy, weight loss, and/or diarrhea, they need to be evaluated by a vet right away. Their vomiting may not be directly tied to eating grass but rather a sign of an underlying illness. 

Does grass make dogs throw up?

No, not usually, but there are exceptions. We know from carefully designed research studies that the majority of dogs who eat grass do not vomit afterwards. However, we have probably all met a dog who ate grass and then vomited at least once in their life. In reality, there are many reasons a dog might puke after eating grass.

One might be pure coincidence, that they were going to throw up anyway and just happened to also eat grass. Another could be that they ate so much grass that it actually irritated their esophagus or stomach; sometimes it is not a true vomit but more of a coughing-up of the grass before it even reaches their stomach. Yet another reason could be that there was something on the grass that caused them to vomit, such as fertilizer chemicals or excrement from another animal. 

 Should I let my dog eat grass?

Whether or not to let your dog eat grass depends on a number of factors. How much do they eat? Do they vomit afterwards? Is this grass relatively safe for them? For the average dog who occasionally chews on some grass in the yard and has no adverse reactions, there is no harm in letting them continue.

For dogs who seem to be obsessively eating grass, whether or not they actually get sick, it is important to speak with your vet and make sure there is not an underlying problem that needs to be addressed there. And if you have reason to believe the grass is not safe for them to eat, certainly take steps to prevent them from eating it and keep your pup safe. 

How to keep keep your grass dog-friendly

1. Create a dog-safe space.

Don’t use pesticides that contain toxic chemicals, and consider making a special dog-safe space in your yard that eliminates plants that may be toxic, too. 

2. Clean up poop.

Reduce the risk of parasite transmission by making sure that your dog only eats grass in your own backyard. Dispose of dog poop regularly, and consider making a pet-waste digester.

3. Keep an eye out for “mean” seeds.

Foxtails — small, dry seeds produced by invasive, grass-type weeds — are prevalent in many lawns and pose a serious risk to dogs. If you have foxtails in your yard, be diligent about removing them (dig or pull them up, or soak them with vinegar at ground level), and watch your dog closely when in the yard.

It’s a good idea to familiarize yourself with all the plants in your yard so you can also keep your dog away from any plants that  may be toxic if eaten, and consider replacing them with dog-safe landscaping. 

4. Beware of rough grasses.

One caveat when it comes to grass consumption: long, rigid grasses with sharp edges have been known to cause throat abrasions and can also cause intestinal blockages. The esophagus is sensitive, and in some cases, dogs who eat this type of grass can experience a serious medical issue. If your dog is coughing, vomiting, not eating, or showing signs of irritation after eating these kinds of grasses, it’s best to contact your veterinarian immediately.

How to stop a dog from eating grass

If you are concerned that your dog is too focused on eating grass, has adverse reactions after eating grass, or that the grass your dog eats may not be safe, there are many ways to stop your dog from eating grass. This includes:

1. Walk your dog on a leash, instead of letting them run free in the yard.

If you are walking with your dog, you can help navigate where they go and intervene right away if they try to chow down on the grass.

2. Use a basket muzzle.

These muzzles are designed for comfort so that your dog can easily pant and even accept treats while wearing it, but they can’t pick up objects and eat them. It is important to train your dog to get used to the muzzle and to make it a positive experience so they are comfortable wearing it.

3. Practice the “Leave it’ cue.

You can work with your dog to learn this cue using positive reinforcement techniques. As your dog becomes more familiar with the cue, it will be easier to redirect your dog from unwanted behaviors like eating grass. 

4. Provide lots of enrichment and exercise.

For all dogs, but especially those who may be eating grass due to boredom or anxiety, this is key. Be sure your dog’s day is filled with plenty of mental enrichment activities like food puzzles, training sessions, socialization, and lots of exercise so that they don’t resort to undesirable habits to fill their time.

If you feel that your dog’s behaviors are extreme, seek out a veterinary behaviorist who can help. These cases can be very challenging and may require expert insight as well as formal training and even medication for dogs who are suffering from extreme anxiety and behavioral disorders.

FAQs (People also ask):

Why do dogs throw-up? 

Vomiting has many possible causes including eating non-food items, infections, parasites, congenital problems, chronic diseases, and more. It is very important to see a vet if your dog is vomiting repeatedly.

Why is my dog coughing?

Coughing also happens for many different reasons, just like in people. Dogs can get infections, develop chronic diseases, and even have anatomical problems that cause coughing. You should always have your dog examined by a vet if they develop a cough. 

How do I dog-proof my yard?

Dog-proofing your yard involves multiple steps. Be sure to consider safe ways to enclose the space, planting non-toxic plants, and blocking off other dangers like swimming pools, fire pits, and barbecues.


daniela lopez

Daniela Lopez

Daniela Lopez is a digital media specialist and long-time contributor to The Bark.

Amy Fox

Dr. Amy Fox, DVM

Amy Fox, DVM is a small animal veterinarian in New York City. A lifelong animal lover, Dr. Fox studied biology in college and then worked as a veterinary nurse before pursuing veterinary school at Cornell University.  She has worked in many different settings including shelter medicine, emergency medicine, general practice, and animal cruelty and forensics. She is especially interested in nutrition, preventative medicine and care for senior pets. Dr. Fox also enjoys writing about veterinary medicine and teaching. In her free time she loves to cook, garden, and go for long runs. 

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