Why is my dog eating grass all of a sudden?


why is my dog eating grass all of a sudden


Grass eating behavior in dogs is as common as digging or panting. According to a survey done by a team of researchers at University of California, nearly 68% of dog owners reported that their furry friends liked to eat grass on a regular basis (almost daily or weekly). In fact, it is the most common plant that dogs eat. Despite it being a common behavior, many dog owners get worried when they see their omnivore friends munch grass crazily and then puke it all out.

So, why do dogs eat grass if it makes them sick? Are they self-medicating? Should you stop your pet from indulging in this common but peculiar habit? Vets regularly face these and many more such questions by pet owners. In this article we will explore this “grass eating” behavior in detail and find out the possible causes behind it. We will also highlight situations where it is okay and where it is not okay to let your pet eat grass.

Grass eating behavior

It is not uncommon to see dogs eat things that we as humans find repulsive. Such things include trash, poop, baby diaper, dirt and so on. One of the things that dogs also like to eat is grass and weeds. This habit of eating things that provide no nutritive value has a scientific name – Pica. Dogs eat grass or any other non-nutritive item due to many reasons. Some of the common answers of the question – why do dogs eat grass are:

  • Taste
  • Boredom
  • Feeling ill
  • As a supplement

The reasons can be many and varied. One dog might eat grass for different reasons at different times. The way a dog eats grass is also indicative of the cause.

Types of grass eating

Dogs eat grass in different ways. You will sometimes find dogs eating grass frantically whereas at other times they may eat it slowly, maybe one grass blade at a time. Here are the two most commonly observed grass eating behaviors among dogs.

  1. Dog eating grass frantically and in large quantity

In this situation you will observe that the dog is desperate to eat grass. The dog will cry and will want to go out as quickly as possible. He will want to rush out and then eat mouthfuls of grass as if he has not eaten anything in days. He will not munch but would rather just swallow whatever is there in his mouth. And then just as suddenly he will throw up all the grass he had eaten. This behavior suggests two possibilities:

  • The dog was feeling sick before eating grass and hence he has self-medicated by eating the plant and then throwing up.
  • The dog became sick after eating so much of grass. Since he swallowed the grass as a whole, the blades of the grass tickled his throat inner lining making him gag and vomit.

Vets are still not sure which pattern holds true all the time. Whether grass eating triggered vomiting or because the dog wanted to vomit he ate grass. But this type of grass eating behavior certainly rules out a few possibilities. These are:

Grass provides nutritional value: In this case the dog is swallowing grass and not chewing it properly. Hence, the grass can hardly provide any nutritional benefit to the animal. It is only through chewing that the large food particles break down into smaller food particles. These are then easier to digest. This way it becomes easy for the body to absorb the mineral and vitamins from the food.

If the dog is swallowing the grass without chewing it then he is definitely not gaining any nutritional benefit from eating the plant.

Dog ate grass because of the taste: Here the dog is eating grass in a hurry. Obviously, he is not gaining any enjoyment while doing so. Hence, we can rule out the possibility that the dog is eating grass because he finds it tasty and that he is enjoying eating it.

  1. Dogs eating small amount of grass slowly

In this situation the dog does not give any previous indication of his desire to eat grass. The dog will be playing happily in the yard and will then start sniffing as if he was trying to find something. He will sniff at the grass and will select a particular grass and will then munch one grass blade at a time. Here, he eats slowly and chews properly before swallowing. He also eats a small quantity. There is generally no vomiting after eating. This type of grass eating suggests two things:

Dog is getting nutritional benefit: Sometimes a dog’s regular diet lacks certain vitamins and minerals. The dog might want to supplement them by eating various non-food things. It is similar to people having a craving for eating white chalk. One hypothesis states that sometimes people have calcium deficiency which they try to overcome by eating chalk. Though, it is always better to consult a doctor in such cases.

In case of dogs, some vets believe that the dog might be lacking fiber in his regular diet and hence he is supplementing his diet by eating grass. There is even a study about a dog that ate grass regularly for several years. Once he was put on a high fiber diet, he stopped eating grass.

We recommend you to seek your vet’s opinion in such cases and find out if your dog’s diet lacks any essential vitamins and minerals. Also try and find out how you can supplement them.

Dog likes the taste of the grass: In hot weather conditions, the taste of cool, juicy grass can be quite welcoming to the taste buds. Dogs might eat grass because they like the taste of it. When they eat slowly, they certainly seem to be enjoying eating it.

Dog is feeling bored: It is also quite likely that your dog is eating grass because he has nothing else to do. He might be feeling bored and eating grass provides him with a good pass time.

Observing the pattern of grass eating becomes important if you want to understand the cause behind it. Each dog will have his own way of doing things and knowing your dog’s way will help you answer “why does MY dog eat grass and weeds?”

Why do dogs eat grass and weeds? – An evolved behavior

It is true that dogs are not grazers like cows, horses or sheep, then why do they show a certain partiality towards eating grass and weeds. In order to understand this behavior fully it becomes necessary to look into the ancestral history of dogs.

Many people believe that dogs are relatives of the wolf family. The domesticated dog of today has evolved from the carnivore wolf. There is a lot of discussion surrounding the eating habits of wolves. Wolves eat small as well as big herbivore animals like rabbits and deer. They tend to swallow small animals whole, along with the stomach content (which can include plants). Some vets believe that this habit of wolves is responsible for the grass eating habit of dogs. Dogs have evolved liking the taste of certain vegetables and plants. Hence, their general partiality towards eating grass.

But, there are many who believe that wolves do not eat the stomach content of large herbivore animals like deer. They generally shake out the stomach contents before eating it. Hence, this habit of grass eating among dogs has nothing to do with the food habits of the wolves.

In fact, the closest historical explanation of grass eating behavior in dogs is that dogs evolved as social scavengers. They were domesticated by prehistoric humans who would give them food. Dogs lived alongside humans and ate whatever was offered. They would also eat whatever was left and hence their habit of trying to find food items in trash evolved. It did not matter to them whether the food was meat or bread. Hence, dogs evolved to become omnivores. Though the structure of their jaw makes them capable of tearing into flesh, they also have the capability to survive on starch rich diet.

Hence, it seems unlikely that grass is a new food item for dogs. They are used to the taste and feel of it and eat it for different reasons.

Reasons behind grass eating

Grass as medicine

This is one of the most common answers to the question – Why do dogs eat grass? Many people believe that dogs eat grass when they are having some stomach problem. After eating grass the dog vomits and thus feels better afterwards. But, this theory does not hold true always.

An important study was conducted by Dr. Benjamin Hart to test the hypothesis that dogs eat grass as a cure for some or the other illness. In this study people were asked a variety of questions related to their pet’s grass eating habits. The questions were related to the regular diet, age, gender, type of plant eaten, any medical history and so on. More than 3000 people responded to the questionnaire. Of these 1571 met the selection criteria.

According to the results of this research on plant eating in dogs it was found that a very low percent (9%) of dogs appeared ill before eating grass or any other plant. The percent of dogs eating grass and vomiting was also not substantial (22%). Grass eating did not seem to be related to gender or diet type.

There was just one significant correlation. Grass eating seemed to be related to the age of the pet.

  • A young pet ate more grass than an older one.
  • Young pets ate more non-grass plants.
  • Young pets also showed fewer signs of illness before eating grass.
  • The vomiting frequency was also less among the younger pets.

Hence, it was concluded in the research that plant eating was not abnormal behavior and dogs eating grass and being sick was more of a coincidence than a fact.

Another study was conducted to prove that grass eating and gastro-intestinal problems are not correlated. In this study a group of dogs was fed standard diet and another group was given a diet supplemented by FOS (fructo-oligosaccharide). The FOS supplemented diet gave the dogs’ temporary stomach problem. Then the dogs were given some grass to eat. It was observed that those dogs that were given the standard diet spent more time eating grass. The dogs that were on FOS supplemented diet did not spend that much time eating grass, contrary to expectations. Hence, it was concluded that gastric problems are not correlated with grass eating in dogs.

Many vets also believe that dogs are not intelligent enough to self-medicate. This ability of animals to self-medicate is called zoopharmacognosy. Here zoo means animals, pharma means medicines or drugs and cognosy means learning or knowing. This ability is particularly seen in monkeys, chimpanzees and baboons. Scientists believe that this behavior of animals has evolved and might have nothing to do with learning.

In order to ascertain whether your pet is eating grass to self-medicate or not, use the following four criteria to judge:

  1. The plant is not a regular part of your pet’s diet.
  2. The plant has no nutritional value to the dog.
  3. Your pet is eating the plant during a particular time of the year, like the rainy season when the chances of infections are high.
  4. Your other pets are not eating the same plant or grass.

These criteria are suggested by biologist Michael Huffman. He came up with them when he was studying the behavior of chimps while working for the Primate Research Institute in Japan.

If you find that your pet is meeting all the four criteria then you can sufficiently deduce that your pet is self-medicating. If not, then he is probably eating grass due some other reason.

Grass as a de-wormer

There is another hypothesis which states that dogs eat grass to purge their system of intestinal worms. The grass wraps itself around the worms inside the intestines. It then comes out with the fecal matter. This hypothesis is the result of a study conducted on chimpanzees.

According to the study, some chimpanzees will eat whole leaves without chewing them. These leaves produce physical irritation in the stomach and increase motility. This leads to the worms attaching to the leaf. When the chimps suffer diarrhea due to leaf eating, the worms get out from the system along with the leaves.

Some vets correlate this behavior of chimps with dogs. They believe that dogs are also trying to get rid of parasites from their system by eating grass blades. The worms inside the dog’s system attach themselves to the grass blades and are flushed out through feces. Probably this is the reason that grass eating is more common in young dogs. Since young dogs are less resistant to worms they need to eat more grass to get rid of the parasites.

Grass as Food

For some dogs grass can also act as food. They can eat grass to satiate their hunger. An important study to highlight this behavior was conducted by the University of New England. The study aimed to provide answers to the following questions:

  • Why do dogs eat grass? Is it because they are hungry?
  • Do they prefer eating grass at a particular time of the day?
  • Do dogs prefer one type of grass over another?

A total of 709 grass eating events were observed and recorded. The dogs were presented with two varieties of grass at different times of the day. The dogs were also given grass before they have had their meal and after it.

It was observed that dogs ate more grass before having their meals than after it. Hence, it was concluded that dogs eat grass when they are hungry. The grass eating behavior decreased as the day progressed. Dogs ate more grass in the morning than they did in the afternoon. This can be because as the day wore on their hunger subsided by having their morning meals. The dogs also showed no particular preference to any specific type of grass.

From the 709 grass eating events, vomiting occurred in just 5 events. All the dogs were checked by vets before the start of the experiment and were certified healthy. Hence, this study again reinforced the fact that dog eating grass and vomiting are not correlated.

Grass is useful to quench thirst

This is an uncommon and generally ignored reason of why do dogs eat grass. As mentioned before, grass provides a cool relief to dogs on a hot day. If a dog has not had access to water through the night, he will feel very thirsty in the morning. He will try to quench his thirst with the first juicy thing he sees. So when you put him out in the yard in the morning he will try to quench his thirst by munching on the juicy cool grass blades.

Grass as a dietary supplement

Grass might contain many essential vitamins, minerals and fibers that the standard diet of the dog lacks. In order to supplement their diet, dogs resort to eating grass. An article on WebMD talks about a study involving a miniature poodle. According to the study the 11 year poodle ate grass regularly for many years. The poodle was medically examined and was found fit. After examining his behavior the vets diagnosed him with plant eating problem. His owner was advised to change the previous diet and provide the poodle with high fiber diet. After changing the diet of the dog and supplementing it with more fiber, the dog stopped eating grass within 3 days. It was concluded that a deficient diet can lead dogs to eat plants.

Some of the important nutrients that grass contains are:

  • Chlorophyll: It helps to fight infection and prevents bad breath.
  • Fiber: It helps improve digestion.
  • Phytonutrients: It helps prevent disease.
  • Digestive enzymes: These include amylase, cellulase, lipase and protease. They help in digestion.
  • Potassium: It helps dogs in the functioning of enzymes, nerves and muscles.

Eating grass helps relieve boredom or anxiety

Some dogs will even munch grass when they have nothing else to do. When they have nothing or no one to play with then, they can resort to munching grass as a time pass. Since dogs are energetic animals they need some sort of physical activity daily. The amount of physical exercise that a dog needs will depend upon its breed. But, some amount of exercise is mandatory for all dogs (except old and sick dogs) to keep them healthy. Dogs also need mental stimulation in the form of puzzles and other such games. In the absence of such physical and mental stimulation dogs can opt to eat grass as an alternative.

Another reason given for grass eating is stress and anxiety. A dog that feels anxious about a situation and does not know how to react will do things that are out of context. Some of these things include drinking excess water, raising one paw, yawing when not really tired and so on. Eating grass can also be one of these behaviors. During such times the dog is simply trying to get your attention and tell you something.

Grass is tasty

One of the simplest reasons of why do dogs eat grass is that dogs like grass. They like the taste of fresh green grass and enjoy eating it. That is why it is such a common behavior and there does not seem to be any specific scientific theory behind it. Most of the theories stated here are mere assumptions.

One thing that has come out through various studies is that grass eating in dogs is a common behavior. But if you are still worrying about this behavior of your dog then you can try various ways to stop it.

How to stop your dog from eating grass?

There are various ways in which you can stop your dog from eating grass and weeds. Before you try any of these techniques you will first have to observe and find out why your dog is eating grass. Is it because he has nothing else to do? Is he hungry or thirsty? Once you establish the cause, you can then easily try and find solution to his problem.

  • Make sure your dog has enough play time and exercise

Dogs love to play. They not only need play to keep boredom at bay but, play also provides them with the much needed exercise. A dog that exercises regularly and sufficiently is happy and stress free. He will eat and sleep well. Ensure that you are walking your dog regularly and giving him enough free play time. Engage him with puzzle toys, chew toys and so on. Games like fetch are fun to play with your dog and are also a good form of exercise for him.

Dogs are social animals and crave companionship. A lonely dog can resort to chewing furniture (or grass) or any other such destructive behavior. You can employ dog walkers, pet sitters or even enroll your pet in a day care center. All these things will reduce his loneliness and might reduce his grass eating.

  • Provide your dog with sufficient food and water at all times

Make sure that your dog has access to fresh drinking water at all times. If you do not give him water during the night then give him water the first thing in the morning. Provide your dog with sufficient meal at the appropriate times. You can even talk to your vet about the amount and timing of meals for your dog.

  • Give your dog a wholesome diet

Your dog needs proteins, fats, fibers, vitamins and mineral to grow properly. Any deficiency in his meal will lead him to find alternative sources of the deficient nutrient. You can also consult your vet about the right kind of food for your dog. The study conducted by University of New England correlated grass eating with age. They found that younger dogs ate grass more often than older dogs. The reason behind this could be that puppies need extra nutrition for proper growth and development.

Make sure that your pet is getting a wholesome diet that is not deficient in any nutrients. You can even try and substitute grass. You can do so by offering other vegetables like carrots and see if it helps your pet. Whenever you decide to make changes to your pet’s diet, do so slowly. Observe how your pet is reacting to the new food and continue only when you feel that all is well.

  • Show you pet to a vet

If you feel that your pet is having some health problems like constipation, diarrhea or vomiting then show him to a vet. Get a full medical examination of your pet to ascertain any underlying disease or health issues. Your pet might be trying to self-medicate by eating grass. By showing him to a vet you will get the right diagnosis and medication for your pet which might decrease or stop his grass eating habit.

If, despite trying all the above techniques your pet is still eating grass then what should you do? Should you let him eat? Is eating grass safe for your pet? Are there any side effects of eating grass?

Should you let your dog eat grass?

There is no problem in letting your pet eat grass as long as the grass/plant/weeds are safe to consume. Here are some situations in which it is not okay to let your pet eat grass:

  • Toxic plants: There are certain varieties of plants that are harmful for animals and can be toxic for your pet. A list of such plants is available at the ASPCA site. Make sure your pet is not trying to munch on these harmful plants.
  • Treated grass: Another reason to stop your pet from eating grass is that the grass or plant could be treated with pesticides. These chemicals can be harmful for your pet. These chemicals when ingested by animals can lead to various health problems.
  • Dirty grass: Some grass, especially grass grown in public places may contain harmful bacteria and worms. This grass when ingested can lead to various stomach problems for your pet.

But, if the grass that your pet likes to eat is safe then there is no harm in letting him indulge in some grass eating. As already stated, grass eating is a common behavior. There is nothing to worry about as long as the grass itself is safe (free from chemicals and non-toxic) for the pet.

Precautions to take if your pet is a regular grass eater:

  • Make sure to grow only non-toxic plants in your garden.
  • Do not use pesticides or dangerous fertilizers on your garden.
  • When you take your pet for a walk or for some play time in the public park, make sure you keep him away from any chemically treated plants. Check for any warning signs in and around the park.
  • If your pet likes to eat grass often you can even plant some grass in your house and let your pet eat it. It will satiate his craving and he will be less willing to eat outside grass.

If however, your dog is eating grass all of a sudden and is showing signs of discomfort (vomiting) then show him to a vet. It will also be wise to consult a vet if your pet is eating grass a lot and is being sick regularly. This might be an indication that all is not okay with his digestive system. It can also indicate that the diet you are feeding him is not working for him. You will need to change the food you were giving him. You can try changing the food or the brand. Or, you can also try and supplement his food with some digestive enzymes. Whatever changes you make, consult your vet first.

Side effects of eating grass

Generally, eating grass does not have any side effects. Occasionally dogs vomit, but as studies have shown, this happens sometimes only. Here are some common reactions or side effects of eating grass:

  • Coughing: Coughing can occur if a grass blade sticks on the inside of your pet’s throat. You can help your pet by giving him a sip of water. The coughing generally subsides quickly on its own. But, if you find that the coughing is persistent and it is making your dog breathless or uncomfortable then you should show him to a vet immediately.
  • Vomiting or spitting: Purging out the grass contents soon after eating them is a common reaction among pets. When they have eaten a bit too quickly or in large quantity, they will spit out or vomit the contents. After vomiting, your pet will feel better. But, if your pet is spitting yellow or white foam then you should consult your vet immediately as it can point to some internal injury.

Sometimes pets will not want to eat or drink just after consuming grass. This can be because the grass blades have hurt their throats. Wait for some time and see if your pet starts eating or drinking on its own. If you think that your pet is in some kind of pain then you should definitely see a vet.

If you do not want your pet to eat grass ever then you can try the following things as a last resort.

Prevent your pet from eating grass

  • Train your pet to not eat grass on command

You can train your pet to not eat grass on command. The training is similar to any reward base training like sit or down. Whenever you see your pet head towards the grass with the intention of eating it, say “No” firmly and ask him to come to your side. When he obeys, you can reward him with a treat.

  • Distract your pet when he eats grass

Keep some toys with you when you take your pet to a public park or even your backyard. The toys will keep him playfully occupied. They will act as a distraction and keep your dog’s grass eating temptations at bay.

  • Put a muzzle when you take him for walks outside

If all else fails then it is better to muzzle your pet dog when you take him to places where there is lots of greenery. This will keep your pet safe and out of harm’s way. And it will also stop you from worrying about your pet eating harmful plants.


Hopefully, the article has comprehensively answered the question – why do dogs eat grass? Grass eating in dogs can be because of a variety of reasons. Most of the times, this behavior is harmless. It will not cause any problem to your dog. If you are still worrying about why your dog is eating grass and want to stop him then it will be better to observe and find out the actual cause behind this behavior. You can then try and apply the appropriate solution. Seeking a professional’s advice will also help you make the right decision for your pet dog.