Why do dogs eat grass?

It can be worrying to see your dog eating grass, especially if  you’ve heard it means they’re feeling unwell. While some dogs may eat grass when they have an upset stomach, it isn’t the only explanation – and the idea that dogs do it purely to make themselves sick is one of the top dog myths. 

In reality, there are several reasons why your dog might be eating grass, from instinctive behaviour and taste to boredom or a need for more fibre. So, if you’ve ever asked yourself, ‘why would my dog eat grass?’, read on to discover the possible causes, when to be concerned and what you can do about it.

So,  why do dogs eat grass?

We can't define one single reason – but one of the following could be a potential explanation for your dog’s habit.

Despite dogs being known for eating meat, it’s thought that eating grass may also come naturally to them. Research has indicated that eating plants may have historically been common among their ancestors – so they might simply be following suit. 

It’s possible that your dog may be missing fibre in their diet. Dogs need fibre to help them digest and pass food, and grass is a fairly good source for them.

Previous studies have shown that dogs that frequently eat grass may stop doing so after switching to a high-fibre diet. However, if your dog is already eating a balanced commercial diet, a nutritional deficiency is less likely to be the reason.

Although it was once thought that dogs eat grass to make themselves vomit when they have an upset stomach, research suggests this isn’t usually the case. Only 9% of dogs were reported to frequently appear ill before eating plants, while 22% were reported to frequently vomit afterwards.

However, it’s still worth looking out for any other potential symptoms of an upset stomach if your dog is eating grass.

While we might not understand it, your dog eating grass could just be because they enjoy the taste. Grass can be surprisingly sweet, particularly during the times of the year when it’s at its most green and fresh.

If you try to stop your dog from eating grass every time they do, they’ll find out it’s a way to get your attention and might be more likely to do it again. 

If you don’t give them attention, but praise and reward them for other behaviours, they might realise it’s not as fruitful as they first thought. 

Similarly, your dog might be bored and looking for some stimulation. If this is the case, some mental enrichment could be in order. 

Dogs use their mouths to help them understand the world around them, so you might find your puppy eating grass as a way to explore their surroundings. This means your puppy might simply nibble the grass, rather than fully ingest it.

Can dogs eat grass safely? The truth is that dogs eating grass itself isn’t harmful – they have the ability to digest plant matter as well as meat, and it can help them add fibre into their diet, too. 

However, there is the risk that your dog could catch an illness or a parasite if they eat grass. For example, snails and slugs can spread lungworm, while grass that’s contaminated by animal droppings could transmit diseases such as parvovirus. 

Similarly, it’s important not to let your dog eat grass or any other plants that have been treated with pesticides, herbicides or chemical fertilisers.

Same dogs can be sensitive to allergens like grass pollen, too. So if a dog with an allergy is in the grass long enough to begin eating it, they might experience some discomfort.

Your dog eating grass infrequently is unlikely to be cause for concern. But if you are ever worried, it’s best to speak to your vet. 

Similarly, if your dog eats grass and avoids their regular meals, eats numerous other non-food items, or if you’ve noticed any  changes in their toilet habits, such as constipation or diarrhoea, a trip to the vet is a good idea.

There’s no evidence that eating grass causes dogs to vomit, but some people do find that their dogs throw up after they eat some. 

If this is something you’ve noticed, it could be that your dog has a stomach problem. It’s best to speak to your vet to rule out anything serious. 

A large amount of grass has the potential to get stuck in your dog’s intestinal tract and cause a blockage – particularly if it’s mixed with other non-food items they might have eaten. 

Call your vet if you notice signs such as retching without producing any vomit, a hard or bloated belly, constipation, restlessness or whining.

In practice, it might be difficult to stop dogs eating grass altogether if they have access to a garden or you pass grassy areas when walking them. 

But if you’d like to stop them in the moment, it’s important to use positive reinforcement. If you shout at your dog, for example, you’re likely to simply make them anxious or scared.

The best course of action is to work out why your dog’s eating grass in the first place. Speak to your vet for advice – they might suggest you work with a behaviourist or trainer if they think it could help. If you have dog insurance with Petplan, you can also use our Pet Expert Chat to speak with a professional about your concerns. Just log into your My Petplan account to get started.

The following tips may also help:

• Feed your dog a healthy diet with all the nutrients they need

• Plan walks immediately after your dog’s meals

• Praise and reward positive behaviours

• Engage your dog on walks to reduce distractions

• Bring treats and toys along on walks

• Keep them on their lead in areas with lots of grass