Why do dogs eat grass?

LAST UPDATED 27 November 2020

This article is written by ADVANCE™ veterinarian Dr Fiona Patterson

Have you ever seen your dog nibble (or perhaps munch) on grass and wondered why? You might have heard that it's because they're trying to make themselves vomit or maybe they have a nutritional deficiency. Is this true, and importantly is grass eating cause for concern?

First off, let's consider a condition known as pica, where a dog craves and consumes inedible objects such as metal, plastic, rocks, sticks and dirt. Pica can be dangerous to health because what is swallowed may be poisonous or damage and block the digestive tract. Most cases of pica in pets are behavioural in origin. However, it's important to rule out any underlying medical condition before coming to that conclusion. Management of pica will depend on the cause and should be discussed with a veterinarian.

Grass eating

When it comes to why some dogs eat grass, a study conducted by the University of California set out to answer this eternal question. The researchers surveyed 1,571 owners of plant eating dogs came away with 6 key findings:

1. Grass eating is a common behaviour in normal dogs

2. It's actually often unrelated to illness

3. Dogs do not regularly vomit after consuming plant material

4. Younger dogs ate plants more frequently than did older dogs and were less likely to appear ill beforehand or to vomit afterward.

5. If dogs showed signs of illness before eating plants, they were more likely to vomit afterward than dogs that did not show signs of illness beforehand.

6. Diet (such as raw food, table scraps and commercial food) played no role in whether or not a dog was a plant eater

So what does this all mean?

The main message here is, if your dog munches on some grass from time to time, it can be considered normal behaviour. Sometimes dogs who are unwell may eat grass and vomit, however they are likely to show other signs of being unwell. Bearing that in mind, it's always advisable that any dog showing signs of illness such as vomiting, diarrhoea or lethargy, be examined by a veterinarian.

What should I do if my dog eats grass?

Although grass eating in dogs does not always equal illness, it's a good idea to take note of the following tips to ensure they are at their happiest and healthiest:

1. Keep dogs away from garden chemicals, fertiliser and toxic plants

Be sure to keep any grass eating dogs away from lawns treated with herbicides, fertilisers or other chemicals, as all of these can be toxic when consumed. The amount of time you need to wait will depend on the product used, so always follow the instructions on the label to the letter.

It's also a good idea to check your garden for any plants or weeds which could be toxic to dogs. These include common ornamental plants such as Brunsfelsia ('Yesterday, Today & Tomorrow'), Cycads and Oleander to name just a few. Check out the ASPCA Toxic and Non Toxic Plants List for a comprehensive guide.

Yesterday, Today & Tomorrow. Image: Wayne Boucher, CC BY-SA 2.5, via Wikimedia Commons

Cycads Image: David Clode via Unsplash

Oleander Image: Peter Schad via Unsplash

2. Quality nutrition matters

Feeding your dog a quality complete and balanced diet is one simple thing you can do every day to invest in their long term health and wellbeing. Look for foods that take into account your dog's breed size and stage of life and are backed by scientific research and development to support their claims.

Dr Fiona's Recommendations

3. Prevent boredom

Grass eating could be a sign of boredom, so take steps to prevent boredom and keep them out of mischief! Interactive toys are a great way to provide physical and mental stimulation, especially when your dog is home alone.


At the end of the day, you can be reassured that if your dog is a fresh grass fiend, it doesn't neccessarily mean an urgent trip to the vet is required. Grass eating on its own is unlikely to be a sign of serious illness, however if it is persistent or accompanied by other symptoms, a veterinary examination is essential.

Further Reading

Want to read more? Check out our other articles:

Premium Pet Food, Is it Worth It?

Exploring Grain Free Pet Food

What is the Best Flea & Tick Treatment?

6 Heartworm Facts All Pet Parents Need to Know

How to Ask Your Landlord for a Pet

Shop All Dog Supplies Now