Why do dogs eat grass? Causes, prevention, vomiting & more

If you’ve ever noticed a dog gnawing on a long blade of grass, you may have wondered why on earth an animal that has developed to hunt and eat meat sometimes grazes like a horse or cow, albeit much less efficient! Some dogs even take it to the extreme and start to Eat other things like wood or sticks that can have serious health effects.

When this is said, grass-eating can occur in almost any breed of dog. It doesn’t matter if it’s a smaller breed like a Yorkie or a really big dog like an American mastiff. Almost every breed is susceptible to eating grass when left alone to explore its independence in your garden or park.

Most people who own a dog will ask this question at some point and come online or go to their veterinarian for an answer. Interestingly, it’s actually a question that has long confused vets and scientists, and we still don’t have all the answers. But we do know some things! Let’s take a look at what they are!

It’s not just sick dogs

Historically, most people thought that dogs only ate grass when they were sick.

Historically it was believed that only dogs ate grass when they were sick to be thrown up. The theory was that the dogs instinctively knew they had to get sick, so they would eat grass. The long fronds tickled the neck and esophagus and triggered the vomiting reflex.

The problem with this theory is that the evidence doesn’t match. In a study, the owners were asked whether their dog eats grass or not and whether they are sick afterward. Only 22% of the dogs that ate grass were sick. And only a very small part showed signs of illness before they started eating the grass. Another study found similar results, with less than a quarter of dogs being sick after eating grass and all dogs being healthy before eating grass.

Although we cannot completely ignore historical theory, it seems more likely that we do not yet know the real reason. Other theories say that the grass corrects a tiny lack of nutrients, that dogs can use this to collect additional information about the dog that went to the toilet there previously, or that it is a natural worm. We do not know it. However, we can agree that in most cases this is likely to be normal. We also know that it is usually not common for a dog to eat grass when he has physical problems such as a torn ACL.

Five reasons why dogs eat grass

Dog eating grass in the park
There are five main reasons why dogs can eat grass.

While the following information is not intended to be comprehensive, there are usually only five reasons why dogs eat grass. Below are the individual reasons as well as an explanation of why your puppy may be eating its share of green treats when it goes outside.

Habit and instinct

Although we don’t know why dogs eat grass, we know that not only our domesticated dogs do. Examination of feces from wild dogs and wolves has shown that grass can be found in their feces up to 70% of the time. This suggests that there must be a common instinctive reason why dogs could eat grass.

Some studies on chimpanzees have shown that they eat indigestible phytochemicals to get rid of worms naturally. The entanglements of the plants move directly through the digestive system and take everything with them when they go. It has been suggested that eating grass is an instinct to purify worms from the intestines of dogs, but there is currently no scientific evidence to support this.


Dogs often prefer to chew on the long fronds that wave in the wind – the same long fronds that are a preferred target for other dogs to urinate and smell. So there is a suggestion that putting the grass in your mouth could be a more effective way to “collect” the smell and information from the grass.

Again, there is no real evidence of this – and I know that my dog ​​prefers the grass that grows in the greenhouse where no other dog has been.


There may be truth in the historical theory that dogs eat grass to make them sick. Finally, we know that some dogs show signs of discomfort before going outside to eat grass, although in one study it was only 8%. While eating grass seems normal to the vast majority of dogs, it can indicate a problem for those who are routinely sick after eating grass.

Causes of nausea that may cause your dog to eat grass include pancreatitis, stomach upset, diabetes, fever, and IBD. However, it is important to look at a picture of your dog as a whole. Not all dogs that eat grass are sick. So, if your dog shows no other signs of illness, they are probably fine.

Lack of nutrition

Pica is the official term for eating non-food items and has been linked to nutritional deficiencies. The theory is that the dog instinctively recognizes a need for a vitamin or mineral and consumes it in the form of grass. There are some problems with this theory. For one, grass goes through the dog’s digestive tract almost undigested – so the nutritional value is probably very low. A second problem with this theory is that the vast majority of dogs have a complete and balanced diet that should cover all of their nutritional needs. Regardless of individual batch problems, these diets are formulated to avoid a lack of nutrients. However, dogs still eat grass.

If your dog is fed a boutique diet, you can try switching to a different wording – ideally, a brand that tries to feed. Not only do these brands calculate that their feed is balanced by checking the profile of each ingredient added, they also regularly feed a cohort of dogs with their feed and measure the actual nutrient intake to ensure that dogs are eating as intended can process.

This is the best way to ensure that a diet is complete and balanced and therefore cannot lead to a nutritional deficiency. Some dry nibbles aren’t as nutritious, so it’s wise to look for food that is specifically tailored to the age of a dog, especially older dogs.

Snacking and hunger

Most veterinarians agree that dogs eat grass as part of their normal lifestyle. Since there are so many dogs and also wild dogs and wolves, this indicates that it is a deeply rooted instinct. Many veterinarians suspect that dogs just like the taste! If they are picky eaters, they may shy away from eating normal food and chew on grass instead.

A study gave a selection of dogs the opportunity to eat grass and observed them. It turned out that dogs were more likely to eat grass before eating their daily meal, and that they also ate grass in the morning rather than in the afternoon. This suggests that eating grass may have a hunger aspect.

frequently asked Questions

Q: Is my dog ​​sick?

A: The vast majority of dogs are not sick when eating grass. This suggests that while some dogs eat grass when they are sick, the vast majority do not. So eating grass doesn’t necessarily mean your dog is sick. Instead, you should look for other clues that your dog is not feeling well. Do you have a good appetite? Are their energy levels normal? Are you restless? Do you drink a normal amount? Do they put themselves in the “prayer position”? It is important to understand your dog’s normal behavior so that you can identify problems earlier. If you think your dog is not quite right, you should ask your veterinarian for advice.

Q: Do other carnivores eat grass?

A: Yes! Wild dogs and wolves eat grass, cats too! In fact, most carnivores are found snacking on grass every now and then. We have no more insight into why these other species eat grass than dogs.

Q: Is eating grass harmful?

A: Eating grass is unlikely to harm your dog. However, there are some exceptions and times when you need to worry. Some dogs eat too much grass, which can lead to constipation of the intestinal tract. This can make dogs very sick and emergency surgery may be required. If your dog seems to be eating a significant amount, you should consult your veterinarian for advice.

Some dogs may eat grass instead of their food. While the lack of a meal doesn’t hurt most dogs, eating so much grass that they’re not interested in dinner suggests a deeper problem. It will also cause problems in the long run because grass cannot be digested properly by dogs and therefore contains very few nutrients that they can use. A dog doing this would not only lose weight quickly but also get nutrient imbalances that can cause problems. If you think your dog is eating grass instead of food, you should contact a veterinarian.

Of course, some grasses are safer than others. If it is known that your dog likes to eat grass, pay close attention to which grass he eats. Grass on the side of the road contains many pollutants that can be harmful to a dog. Grass that has been sprayed with weed killers, moss killers, pesticides, or even fertilizers is even more worrying. Many of these compounds are toxic to dogs and cause a variety of effects from seizures to death.

Don’t forget that some things that look like grass from a distance may not be grass. Bluebells, daffodils, and other spring onions can have grass-like clumps, but they contain toxins that often make dogs sick. Likewise, poisonous plants can be hidden in a tuft of grass, so it is advisable to be careful.

If you know or suspect that your dog has eaten grass that contains toxins or poisonous plants, you should contact your veterinarian or an animal poison line.

It is important to remember that most dogs like to snack on long grass – this is a commonplace where ticks hide and wait to hold on. You should make sure that your dog has current flea and tick prevention, especially if he is prone to snacking. Eating grass is also a way for dogs to catch worms and diseases like parvovirus. You should therefore ensure that your pet is regularly dewormed and also up to date about its vaccinations.

Q: When should I worry that my dog ​​is eating grass?

A: Most dogs that eat grass have no negative effects. You will notice grass in the stool a day or two later and your dog will have been his normal self throughout.

However, you should worry if your dog appears to be eating grass all the time or if it eats more grass than dog food. You should also be concerned if your dog shows other signs of illness such as vomiting, diarrhea, abdominal pain, or lethargy more than once.

Some dogs are known to eat grass when their stomachs widen – a dangerous situation that often leads to gastric dilatation-volvulus or GDV. Symptoms include gagging or vomiting but without vomiting. This is an emergency situation and these dogs should be taken directly to the vet.

Although less common in dogs than cats, dogs may have a piece of grass stuck in their throat, causing sneezing, coughing, or repeated swallowing. This has to be removed surgically. If you see any of these signs, you should take your dog to the vet.

Q: Can I stop my dog ​​from eating grass?

A: If your dog shows no signs of disease, is fully and balanced, and only occasionally eats snacks on grass, it is likely that they are normal. It is not necessary to prevent them from behaving normally and can be harmful in some cases. It is, therefore, worth discussing this with your dog trainer before you decide to intervene. Bitter sprays and training techniques can help stop dogs for whom grassnacking becomes a problem.

Final thoughts

Although we have plenty of ground under our feet and most likely have found at least one of the reasons why your puppy eats grass, we always recommend taking your dog to your local veterinarian if you have any questions. Although we can give you advice, you know your dog better than anyone and can often judge whether your puppy is not feeling well.

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