Why do dogs eat grass?

18 January 2024 - 6 min read
This article is not intended to be a substitute for professional veterinary advice, diagnosis, or treatment. Always seek the advice of your veterinarian with any questions you may have regarding your pet’s care, treatment, or medical conditions.
Dog eating grass

One moment you and your pup are out for a lazy afternoon stroll, and the next they’re treating the ground beneath their feet like a salad bar.

To many dog parents, grass-eating is an all-too-familiar behaviour. But is it actually a problem if your dog enjoys a leisurely lawn lunch? Does it point to some dietary deficiency? Can it make them sick? Or is grass-eating just part of a dog being a dog?

From ancestral instincts to dietary needs, there are several theories about why some dogs choose to graze like hungry cattle. Whether your dog is a frequent grass-eater or just an occasional herbivore, understanding their behaviour can help you keep them happy and healthy.

The curious case of canines and grass: 3 theories

Black and Tan Chihuahua in the grass

Dogs eating grass is an incredibly common behaviour, and the truth is, we're not entirely sure why they do it. However, several theories might shed some light on this peculiar canine habit.

Theory #1: ancient instincts

First, grass-heating might just be a case of ancient natural instincts taking hold. All you need to do is look at your dog’s lupine cousins. Wolves—your dog’s ancestors—are known to consume plant matter, suggesting that grass-eating may be hardwired into canine DNA. Even after centuries of domestication, dogs can still get a little bit wild.

Theory #2: nutritional deficiencies

Another theory is that dogs might eat grass to fulfil certain nutritional needs or to compensate for a deficiency in their doggy diet. Though predominantly carnivores, it’s possible that dogs might seek out grass as a source of fibre or other nutrients that are missing from their regular meals (though at least one study has suggested that this may not be a very large factor in the behaviour).

Theory #3: boredom

Finally, your pup might simply be, well, bored. Just as restless humans might munch on potato chips when they’re not actually hungry, dogs might turn to grass as a way to pass the time rather than to meet an unmet dietary need. Actually, a 2019 study from Japan found that neutered dogs and younger dogs—both of which have a higher tendency toward boredom and attention-seeking behaviours—are more likely to eat unnatural foods like grass.

Whether it involves adjusting their diet, providing more exercise and stimulation, or simply accepting that lawn-chomping is a normal dog behaviour, knowing why your dog eats grass is a crucial first step in deciding what to do about it—if anything.

Is it safe for my dog to eat grass?


Here’s the good news: grass-eating is often harmless for dogs. We can’t stress this enough: A lot of dogs are world-class grass-nibblers, and negative effects are rare.

However, there are certain circumstances where eating grass could be harmful. In cases where grass is treated with chemicals like pesticides or fertilisers, consumption can lead to poisoning. So you should be aware of what products are used on any grass your dog has access to.

And while grass itself is usually safe for dogs, it's important for pet owners to be cautious about other common plants that can be dangerous to dogs, which they might accidentally eat while munching on grass. Some common garden plants like azaleas, daffodils, and lilies can be extremely toxic.

Also, keep in mind: While occasional grass-eating usually isn’t a cause for alarm, excessive consumption may point to a health issue. If your dog is gulping down grass like it’s their primary food source, they may be suffering from gastrointestinal upset or some other illness.

So...SHOULD my dog eat grass?

A low shot image of two dalmatian dogs leading through the long grass on their evening walk through the countryside.

Grass-eating may not always be harmful, but is it, like, good?

It’s possible that your dog might eat grass to shore up a fibre-poor diet or to address any other nutritional deficiencies. But this doesn’t mean you should encourage your dog to eat grass. If your pup is eating too much grass, you should feel inspired to make changes to their regular food habits. If their diet is nutritionally complete, they might not eat so much of the green stuff.

Also remember: While dogs aren’t 100% carnivorous like cats, indeed vegetarian dog foods are a thing, most canine diets are heavily meat-based. If regular grass eating is interfering with their protein intake, that’s another signal to reevaluate your dog’s diet.

It's probably not a problem if your dog eats grass, and you don’t always need to go out of your way to stop them. But you shouldn’t exactly be encouraging them to chow down on those green blades, either.

If your dog needs a change in diet, you should handle it at home. And it’s a good idea to consult your vet, who can help you craft a balanced, nutritious diet for your chlorophyll-curious canine.

When to be concerned

While grass-eating is often a normal behaviour in dogs, there are certain signs that could point to a troubling health issue.

Excessive eating

If your dog frequently eats large amounts of grass or even seems obsessed with eating grass, that could signal an underlying canine health issue. Your dog’s grass eating could be designed to induce vomiting, so they can relieve some kind of stomach discomfort. And again, they could be trying to address a nutritional deficiency.

In these cases, monitor their behaviour closely and take them to the vet.

Symptoms to watch out for

Be watchful for symptoms like vomiting and diarrhoea, or other signs of gastrointestinal distress, after your dog eats grass. If these symptoms are frequent, it could indicate an underlying health issue that needs to be addressed.

Again, it’s possible that some dogs are eating grass in an attempt to induce vomiting, so they can relieve gastrointestinal discomfort or expel indigestible materials. But then again, not all dogs vomit after eating grass, and when they do, they may just be sick.

When to consult a veterinarian

If you notice any changes in your dog's overall health, behaviour, or appetite in conjunction with their grass-eating, it's time to consult a veterinarian. This is particularly important if the grass-eating is accompanied by other symptoms of illness.

While eating grass can be a normal part of your dog's behaviour, it’s always better to err on the side of caution when it comes to the health of your hungry pup.

Grass seeds of destruction 

Interestingly enough, grass seeds pose more of a canine health risk than grass itself. These seeds are small, pointy, and easily become trapped in a dog’s fur, where they can cause injury by piercing the skin. This is particularly troublesome for dogs with long hair around their feet or ears. 

Grass seeds are common in meadows and woodlands with long grass, especially in the summer months. Common symptoms of grass seed injuries include constant licking of the paw, limping, head shaking, sneezing, eye redness or discharge, and excessive attention to a sore spot on their skin. To prevent these issues, just check your dog's fur for grass seeds after they’ve been outside in tall grass.

While grass seeds pose more of a threat to your dog’s skin than their GI tract, eating too much grass seed can still lead to issues such as diarrhoea and an upset stomach. And some grass seeds are coated with chemicals that can be harmful if eaten. If you’re planting grass seed, you should strongly consider using pet-friendly seeds and fertilisers.

How dog insurance can help

While it's normal for dogs to nibble on grass, quantity is key.

Just be vigilant for excessive eating, keep a close eye on any changes in their grazing habits, and don't hesitate to consult a veterinarian for persistent or obsessive behaviour. Oh, and keep an eye out for grass seeds, which can pose a real danger to your dog's health.

And if your dog is indeed gorging on grass because of a health problem, having dog insurance can financially prepare you to seek out any treatments they might need.

Dog and human sharing a celebratory high five

Add the MoneyBack optional extra for 20% back at the end of the policy year if you don’t need to claim

Dog and human sharing a celebratory high five