Why is my dog eating grass?

Why does your dog eat grass? Discover the common reasons behind grass eating, what research tells us about this behaviour, and when it could be a sign that something deserves closer attention.

BEHAVIOUR

8/11/20266 min read

Quick Answer

Dogs eat grass for many different reasons, and in most cases, occasional grass eating is considered normal canine behaviour. Some dogs appear to enjoy the taste or texture, while others may eat grass when exploring, foraging, or experiencing mild digestive discomfort.

Despite the common belief that dogs eat grass specifically to make themselves vomit, research suggests the explanation isn't quite that simple.

Understanding when, how often, and under what circumstances your dog eats grass can help you distinguish normal behaviour from something worth discussing with your veterinarian.

Why Do Dogs Eat Grass?

Watching your dog enthusiastically graze on the lawn can seem strange.

Dogs are not strict carnivores, and plant material can form part of their dietary and exploratory behaviour. Grass eating has been observed in both domestic dogs and wild canids, suggesting that consuming vegetation isn't necessarily abnormal.

The more useful question isn't simply:

"Why is my dog eating grass?"

but:

"Has something changed about the way my dog is eating grass?"

Frequency, urgency, accompanying symptoms, and changes in behaviour can tell us far more than the grass eating itself.

Do Dogs Eat Grass Because They Feel Sick?

This is probably the most common explanation owners hear.

A dog eats grass, vomits shortly afterwards, and it seems logical to assume that the dog deliberately ate the grass in order to be sick.

However, studies investigating plant-eating behaviour in dogs suggest that most dogs don't appear unwell before eating grass, and vomiting doesn't occur after every episode.

This means grass eating shouldn't automatically be interpreted as a dog's way of treating an upset stomach.

Some dogs may seek grass when experiencing gastrointestinal discomfort, but this appears to explain only some cases rather than grass eating as a whole.

The sequence of events matters.

If your dog suddenly becomes restless, urgently searches for grass, consumes large quantities and then vomits, digestive discomfort may be involved.

Occasionally nibbling grass during a relaxed walk is a very different behaviour.

Some Dogs Simply Like Eating Grass

Sometimes the simplest explanation is the right one.

Dogs explore their environment through their noses and mouths, and fresh grass can offer an interesting combination of:

  • Smell

  • Taste

  • Texture

  • Moisture

  • Chewing sensation

You may even notice that your dog prefers particular types of grass or only grazes at certain times of year when new shoots are soft and fresh.

For these dogs, grass eating may simply be another form of environmental exploration.

Grass Eating May Be a Natural Foraging Behaviour

Dogs have retained many behaviours inherited from their ancestors, including scavenging and foraging.

Eating doesn't necessarily begin and end with what's placed in a food bowl.

Sniffing, searching, investigating and occasionally consuming safe plant material can all form part of the way dogs interact with their environment.

A dog slowly selecting individual blades of grass while sniffing around a field may therefore be displaying a very different behaviour from a dog desperately swallowing mouthfuls of grass.

Context matters.

Is My Dog Missing Something From Their Diet?

Another popular theory is that dogs eat grass because they're deficient in a particular nutrient.

While dietary factors shouldn't be dismissed entirely, occasional grass eating doesn't automatically mean your dog's diet is nutritionally incomplete.

Dogs fed complete and balanced diets may still eat grass.

Fibre has also been proposed as one possible factor because plant material provides roughage. However, there isn't enough evidence to assume that every grass-eating dog needs additional fibre.

If your dog's grass eating has increased significantly, particularly alongside changes in appetite, stool quality or body weight, it's worth discussing their overall diet with your veterinarian rather than adding supplements or changing foods without guidance.

Could Hunger Play a Role?

For some dogs, grass eating may occur more frequently when their stomach is empty.

You might notice grazing:

  • Early in the morning

  • Before breakfast

  • Late between meals

  • At predictable times each day

This doesn't necessarily mean something is wrong.

However, if grass eating regularly occurs alongside nausea, lip licking, repeated swallowing, abdominal discomfort or vomiting—particularly vomiting bile—it's worth mentioning the pattern to your veterinarian.

Keeping track of when grass eating occurs in relation to meals can provide useful information.

Boredom and Behaviour Can Also Influence Grass Eating

Not every explanation is nutritional or digestive.

For some dogs, grazing may simply provide something interesting to do.

A dog spending time in the garden with little stimulation may discover that pulling, chewing and eating grass is entertaining.

Dogs may also repeat behaviours that they find soothing or rewarding.

Providing appropriate opportunities for:

  • Sniffing

  • Exploring

  • Chewing

  • Foraging

  • Interactive play

  • Food-based enrichment

can help meet these behavioural needs in more varied ways.

Related Article: Why Mental Enrichment Is Just as Important as Physical Exercise

Why Does My Dog Sometimes Vomit After Eating Grass?

Grass can occasionally irritate the stomach or throat, particularly when a dog eats a large quantity quickly.

Long blades may also trigger gagging or vomiting.

This doesn't necessarily mean the dog ate the grass because they needed to vomit.

The vomiting may instead be a consequence of eating the grass.

An isolated episode in an otherwise bright, comfortable dog may not be concerning. Repeated vomiting, however, shouldn't simply be attributed to grass eating without considering other possible causes.

When Grass Eating Deserves More Attention

The behaviour becomes more important when there's a noticeable change in your dog's normal pattern.

Contact your veterinarian if frequent or excessive grass eating occurs alongside symptoms such as:

  • Repeated vomiting

  • Diarrhoea

  • Loss of appetite

  • Weight loss

  • Lethargy

  • Abdominal discomfort

  • Excessive drooling

  • Repeated swallowing or lip licking

  • Changes in thirst

  • Changes in stool

  • Unusual restlessness

A sudden obsession with eating grass in a dog who rarely did so previously is also worth paying attention to.

The grass itself may not be the problem—it may simply be one visible sign that your dog is feeling different.

Not All Grass Is Safe

Even when grass eating itself is harmless, what is on or around the grass may not be.

Dogs shouldn't be allowed to graze in areas that may recently have been treated with:

  • Herbicides

  • Pesticides

  • Fertilisers

  • Weed killers

  • Other garden chemicals

Public areas can present additional risks because you may not know what has been applied.

Grass can also be contaminated with faecal material from other animals, potentially exposing dogs to parasites or pathogens.

Certain plants growing amongst grass may also be toxic to dogs.

If you're unsure what's growing in an area, preventing your dog from eating vegetation is the safer option.

Grass Seeds Are a Different Problem

Eating grass shouldn't be confused with exposure to grass awns or sharp grass seeds.

Certain grass seeds can become lodged in a dog's paws, ears, eyes, nose or coat and may migrate into tissues.

During grass-seed season, checking your dog's coat, paws, ears and areas between the toes after walks can help identify potential problems early.

Dogs with long or dense coats may require particularly careful checks.

Should I Stop My Dog Eating Grass?

If your dog occasionally nibbles clean, untreated grass and remains otherwise healthy, there's usually no reason to panic.

Rather than immediately stopping the behaviour, observe it.

Ask yourself:

  • Is this occasional or frequent?

  • Is my dog calmly grazing or urgently consuming grass?

  • Does it happen before meals?

  • Does vomiting follow?

  • Are their stools normal?

  • Has their appetite changed?

  • Is this new behaviour?

Patterns are often more informative than individual episodes.

Keeping a Grass-Eating Log Can Help

If your dog frequently eats grass, keeping a simple record can help reveal patterns that might otherwise be missed.

Record:

  • Date and time

  • Whether your dog had recently eaten

  • Approximate amount of grass consumed

  • Behaviour before eating it

  • Whether vomiting occurred

  • Stool consistency

  • Appetite

  • Any other unusual symptoms

This information can also be useful if you later need to discuss the behaviour with your veterinarian.

Remember

Eating grass doesn't automatically mean your dog is sick.

For many dogs, occasional grazing appears to be a normal behaviour associated with exploration, taste, foraging or individual preference.

What matters most is context and change.

A dog casually nibbling a few blades of grass during a walk is very different from a dog suddenly devouring grass while showing signs of nausea or discomfort.

Learning your dog's normal habits makes it much easier to recognise when something genuinely changes.

Frequently Asked Questions

Does my dog eat grass to make themselves vomit?

Not necessarily. Research suggests that many dogs eat grass without appearing unwell beforehand, and most grass-eating episodes don't necessarily result in vomiting. Some dogs may eat grass when experiencing digestive discomfort, but it shouldn't be assumed to be the reason in every case.

Is eating grass normal for dogs?

Occasional grass eating can be normal, particularly when your dog is otherwise healthy, eating normally and showing no signs of gastrointestinal discomfort.

Should I stop my dog from eating grass?

Occasional grazing on clean, untreated grass isn't usually a cause for concern. However, prevent your dog from eating grass in areas that may have been treated with pesticides, herbicides, fertilisers or other chemicals.

Why does my dog eat grass and then vomit?

Eating a large amount of grass can itself irritate the stomach or throat and may trigger vomiting. In other cases, a dog experiencing nausea may seek out grass. Repeated vomiting should be discussed with your veterinarian.

Does eating grass mean my dog needs more fibre?

Not necessarily. Dogs eating complete and balanced diets may still eat grass. If you suspect a dietary issue, discuss your dog's diet with your veterinarian before adding fibre or supplements.

Why has my dog suddenly started eating lots of grass?

A sudden change deserves more attention than occasional habitual grazing. If increased grass eating is accompanied by vomiting, diarrhoea, appetite changes, lethargy or other symptoms, contact your veterinarian.

Further Reading

  • Understanding Your Dog's Digestive Health

  • Why Does My Dog Eat Things They Shouldn't?

  • Why Mental Enrichment Is Just as Important as Physical Exercise

  • Understanding Canine Body Language

  • When Should I Call the Vet?

  • Common Garden Hazards for Dogs