Why Do Dogs Eat Grass and Vomit?

Updated: 12/6/20232-4 minutes
A child sleeping with a dog

Dogs may eat grass and vomit to alleviate nausea (like people, dogs with an upset stomach likely feel better after throwing up). 

There are several theories about why dogs might graze on grass, however. They may be trying to make up for a dietary deficiency, introduce more fiber into their diet or they might simply like the taste and texture.   

If you’re asking yourself, “Why do dogs eat grass and vomit?”, you’re probably not alone. Though dogs and humans have a great bond, sometimes our canine companions do things we find puzzling.  

The good news is a dog eating grass on occasion is nothing to worry about. This is not uncommon behavior.  

It might surprise you to learn, however, there isn’t much evidence to tell us why they do it. Behaviorists and veterinarians have been perplexed by the behavior for decades. 

Why Do Dogs Eat Grass?

The truth is no one knows for sure why dogs eat grass, but here are some common theories. 

Nausea

A dog eating grass and throwing up may seem ill. In fact, it’s a widely held belief among dog owners that if a canine feels nauseous, they’ll eat grass to induce vomiting.   

This belief, however, still only remains a theory. According to the Veterinary Centers of America, it’s quite unusual for dogs to vomit after eating grass, with less than 25 percent doing so and only a further 10 percent displaying signs of illness beforehand.   

It’s true digestive upset is one of the leading causes of vomiting in dogs, and a green type of vomit could mean they ingested a leafy substance. However, reasons like changing dog food too abruptly are more common than eating grass. 

They Like the Taste of It

Another reason why dogs eat grass could be because they like the taste of it. Dogs are descended from wolves, and, as such, they are natural omnivores—meaning they might be grazing in your backyard to forage.   

Nutritional Deficiencies

It’s tempting to think your dog eats grass to make up for nutritional deficiencies in their diet. While it’s true that grass is rich in fiber (an essential nutrient for canines), more studies need to be done to establish a link between grass-eating and a deficiency.   

Nonetheless, if you’re concerned your dog may be eating grass because they’re not getting the nutrients they need, talk to your veterinarian about making sure they’re consuming complete and balanced dog food.  

If your dog is already eating a complete and balanced diet, a nutritional deficiency is likely not the culprit.   

Boredom

When dogs are understimulated, they may engage in behaviors to alleviate their boredom. These behaviors can include digging, excessive chewing and eating grass, among others. That’s why it’s essential to keep your pet both physically and mentally stimulated.   

Dogs Might Need Grass in Their Diet

Another explanation for why dogs eat grass could be related to how they’ve evolved. This theory relates to the fact that wild canids eat all of an animal when they catch it.  

The animals that wild canids—your dog’s ancestors—would catch and eat were usually herbivores. This means when wild canids ate these animals, they might also have eaten a lot of grass and plants in the intestines of their prey.   

Wild canids, such as foxes, are known to eat certain berries and other plant material, supporting the idea that dogs eat grass because it’s an inherited behavior.   

Is My Dog Sick if They Eat Grass & Vomit?

A dog eating grass and vomiting isn’t necessarily a cause for concern, especially if it’s an isolated incident. If it happens once, they likely are dealing with passing nausea.  

If, however, it becomes a recurring behavior on walks or when they play in the yard, contact your veterinarian.  

Your dog isn’t sick if they occasionally graze on grass. Some canines, however, may chew on it as a result of a condition known as pica, which is often related to gastrointestinal disease. Dogs with pica persistently eat and chew on objects and substances that have no nutritional value.  

In addition to grass, your pet may feast on things like clothing, garbage and dirt. If your dog exhibits this kind of behavior, let your veterinarian know. If untreated, regularly eating non-food items may lead to a digestive disorder. 

Can Dogs Eat Grass?

Yes, dogs can eat grass. It’s a normal behavior and not a concern unless they’re doing it excessively or it’s a sudden change in how they act.  

If your dog sometimes eats grass in your yard or garden, however, make sure it hasn’t been sprayed with pesticides or other chemicals. Also check for poisonous plants.  

How to Stop a Dog From Eating Grass & Throwing Up

If you want to prevent your dog from eating grass because you’re concerned it’s causing them to throw up, talk to your veterinarian. They can help figure out if it’s the reason your pet vomits, or if this behavior is a symptom of an underlying illness. 

One strategy you can try to stop your dog from munching on grass is changing their diet. This could be helpful if they have a nutritional deficiency. Ask your veterinarian for recommendations. 

Additionally, digestive supplements may help a nauseous dog with a sensitive stomach, while calming supplements might be a good option for canines who eat grass out of nervousness. 

In the event your pet needs more stimulation, make sure you’re providing them with ample opportunity to exercise and give them toys to play with when in the yard.  

Puzzle games and other enrichment activities will help keep your dog happy, healthy and less inclined to engage in problematic behaviors.  

Remember, if your dog starts ingesting a lot and doesn't seem to be their usual self, or if they're repeatedly eating grass and vomiting over a period of a few hours, it's time to contact your veterinarian. 

If you are still concerned about your dog eating grass, discuss it with your veterinarian, just in case, so they can check your pet and rule out any possible health concerns.   

Discover more insights into dog behavior and more from our experts on our Pet Expertise page. 

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