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Published: Feb 02, 2024 8 min read

Many veterinarians acknowledge that dogs eating grass is an expected behavior, yet the reasons behind it are complex.

While some dogs may consume grass due to deficiencies in their diet — lacking in vitamins, nutrients or fiber — various causes prompt this behavior despite grass offering minimal nutritional value. Keep reading to uncover insights into this intriguing habit.

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Four reasons why dogs eat grass

Dogs eat lots of things they shouldn't consume. Known as pica, the persistent drive to eat non-food items without nutritional value can lead to a host of dental and gastrointestinal issues. In fact, digestive problems caused by swallowing foreign items rank among the top pet insurance claims filed by dog owners.

Fortunately, veterinarians agree that grass-eating is mostly harmless. It can, however, be an indicator of something else. Here are the four reasons why your dog might be eating grass.

1. Natural instinct

Dogs are omnivores and their wild canine ancestors might've eaten grass as a natural way to rid themselves of intestinal parasites. A dog's digestive system struggles to break down grass. As it passes through the dog's stomach and intestines, the fibrous texture aids in cleaning out any unwanted parasites.

Domestic dogs may not need to rid themselves of parasites this way anymore. Still, the behavior persists because it's instinctual. This theory also explains why younger dogs eat grass more often: younger dogs are more likely to get intestinal parasites than older ones.

2. Nutritional deficiency

Dogs might also eat grass if they’re lacking a nutrient-rich diet or to improve digestion since grass is high in fiber.

One study observed an 11-year old poodle who ate grass daily only to vomit shortly after. This problem persisted for years. The veterinarians advised the owner to add more fiber to the dog’s diet to see if it would help. Once the dog switched to a high-fiber diet, the owner reported he stopped eating grass and throwing up.

3. Curiosity

Dogs are known for exploring the world with their mouths because why not? Grass isn't an exception. Your dog might nibble on grass out of curiosity, because it’s fun or simply because they like the taste.

4. Boredom or anxiety

Dogs need daily physical and mental stimulation in the form of exercise or play. When they don’t receive it, they may find other outlets to release the pent-up energy — excessive licking, destructive chewing and yes, eating grass. It could also be an anxiety response in that they chew on grass to calm their nerves.

Pet parents may unknowingly reinforce grass-eating behavior by intervening or calling out their dogs while eating grass. Dogs may interpret this engagement as a reward for their behavior and will likely do it again. After all, they're learning they get your precious attention whenever they do it.

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Do dogs eat grass when they are sick?

Many dog owners think dogs eat grass when they don’t feel good to settle their stomachs and induce vomiting. However, some studies suggest this isn’t the most likely explanation for the behavior.

One example is a study that surveyed 1,571 dogs on plant-eating behavior. Of the dogs, only 9% were sick before eating grass, and 22% frequently vomited after. This study, along with others of a similar nature, suggests that not feeling well isn’t a widespread reason they consume grass. However, it may still be the motive for some dogs.

The reason some dogs vomit after eating grass is commonly believed to be because blades of grass can tickle their throat. Some other things can cause vomiting as well, which we dig into below.

Is it ok for dogs to eat grass?

Grass itself isn't harmful, but eating it could expose your dog to toxic chemicals and parasites. Eating a lot of grass could also lead to constipation and digestive problems due to its high fiber content.

Pesticides and herbicides

Grass treated with pesticides, herbicides or fertilizers could harm dogs and lead to pesticide poisoning. Symptoms include drooling, vomiting, diarrhea, lethargy, skin or eye irritation and trouble breathing.

There's also a possible link between herbicide-treated lawns and an increased cancer risk. The Humane Society highlights two studies that found a higher risk of lymphoma in dogs exposed to 2, 4-D herbicide, the main ingredient in products such as Trimec, Triplet, End Run and Q4. More research must be done to reach a definitive answer, but in the meantime, it’s better to be safe than sorry.

Read the product instructions thoroughly if you apply these chemicals to your yard. The general recommendation is to allow all pesticides, herbicides and fertilizers to fully dry and keep your pet away from the area for at least two days.

Fecal matter

When dogs consume grass, they can also ingest feces from other animals, potentially contracting various illnesses.

Parvovirus, commonly known as parvo, is a potentially lethal virus transmitted via animal droppings. Animal waste can also contain eggs or larvae from intestinal parasites like roundworms, heartworms, tapeworms, hookworms and whipworms.

You can minimize these risks by keeping up with your pet's vaccination schedule and taking them to the vet for routine deworming and parasite screenings.

Should I take my dog to the vet for eating grass?

Pet owners don't need to worry about their dog's grass-eating behavior if other signs of illness don't accompany it.

Call your veterinarian if your dog shows any of the following signs in conjunction with this habit, as some of these additional symptoms may indicate medical conditions or other stomach issues, such as pancreatitis or inflammatory bowel disease.

  • Lethargy
  • Diarrhea
  • Weight loss
  • Lack of appetite
  • Sudden or excessive grass-eating behavior

Compulsive grass-eating — especially if this puts your dog at risk of choking or damaging their digestive system — might also require the input of a professional such as a veterinary behaviorist.

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Why Do Dogs Eat Grass FAQs

Does a dog eating grass mean anything?

A dog eating grass can mean a few different things. First, they may just like the taste of it, are bored or anxious, or are acting on their natural canine instincts. Alternatively, grass-eating could mean your dog has a nutritional deficiency and needs more fiber in their diet. Most of the time, this behavior isn’t a cause for concern. Still, you should call your animal hospital if you notice signs of lethargy, diarrhea, weight loss, lack of appetite or sudden and excessive grass-eating, as these could signify a health issue.

How do I stop my dog from eating grass?


First, try to identify why your dog is eating grass. If they're bored or have anxiety, add more play time, exercise and mental stimulation to their routine.

Dogs that eat grass in the morning and throw up soon after might have discomfort due to an empty stomach. Try to feed your dog earlier in the morning to see if this dissuades the behavior.

If the problem persists, consult a veterinarian. They may recommend switching your dog's diet or refer you to a vet behaviorist who can teach you how to redirect the grass-eating habit.

Why do dogs eat grass when sick?

There's no clear answer to why dogs eat grass when sick. One popular theory is they do this to induce vomiting when they have an upset stomach. Still, studies haven't found definitive proof of this. A small percentage of dogs observed in these studies showed previous signs of illness, but most seemed perfectly healthy before and after eating grass.

Can dogs eat lemongrass?

Lemongrass is toxic to dogs if ingested in high amounts. It contains essential oils and cyanogenic glycosides, which can cause stomach upset.

Summary of Money's Why Do Dogs Eat Grass?

Various reasons could drive your dog to nibble on roughage.

Some do it because they're bored, anxious or under-stimulated, or simply because they like the taste of grass. Others may eat grass because their wild canine ancestors did it, and the behavior is inherited genetically. Dogs may also resort to grass-eating if they don’t have a balanced diet or even to alleviate the discomfort of an empty stomach.

Most vets agree that eating grass is normal dog behavior. However, you should call your vet if you notice any additional signs of illness (lethargy, lack of appetite, diarrhea). The same applies if you believe that grass-eating is related to other behavioral problems like anxiety or compulsiveness.

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