Why do dogs eat grass?
This article is written by ADVANCE⢠veterinarian and last updated by
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.
The myth that dogs eat grass only to induce vomiting is in fact false. Only a small number of dogs actually vomit after eating grass, as discovered in research studies. If the dogs were already showing signs of illness prior to eating grass, then they were more likely to vomit. Grass eating behaviour is found to be mostly unrelated to illness and may actually be an inherited instinct from wild ancestors. This instinct may have helped purge intestinal parasites from their system - similar to wild chimpanzees - and younger dogs were indeed more likely to eat grass, supporting this theory as young animals are more susceptible to parasites with a still developing immune system (Dr Hart, 2008).
Reasons Dogs Eat Grass
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
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.
Health and Nutritional Reasons
1. Upset stomach
Studies have found that most dogs are in fact, healthy and free of digestive issues and simply eat grass as their normal behaviour. Dogs who already have illness prior to eating grass are more likely to vomit afterwards. In 2010, a specific study was conducted to investigate whether dogs with gastrointestinal upset would affect grass eating behaviour. They found that this behaviour was less frequent and the sick dogs also spent less time eating grass, compared to the normal healthy dogs with no illness. Similar to other studies, they did not find vomiting as a regular symptom and it was not likely that the dogs used grass to induce vomiting.
2. Nutritional deficiencies
Dogs with Pica may display unusual eating habits such as chewing or ingesting soil, rocks, along with grass, or wood and other odd substances with no nutritional benefit. Pica could indicate an underlying nutritional deficiency, or could be a compulsive behaviour, or other behavioural issues like anxiety or boredom.
3. Desire for fibre in diet
Grass can provide roughage for your pet when their diet is lacking in fibre. This can help to improve gut motility and promote healthy, firm stools. Adding supplements such as psyllium husk or pumpkin to your petâs food can help increase fibre intake and can be a safer, better alternative to them chewing up the lawn. Eating grass is generally considered quite safe but do be mindful of any pesticides or fertilisers, and keep your dog on regular worming prevention.
Behavioural Reasons
1. Boredom
Bored dogs may chew grass for something to do and it helps them pass the time. Leave them long lasting treats and interactive toys to keep them stimulated through the day while you're busy at work. Understanding your dog's energy levels can help you address their boredom and keep them happy. Working breeds like Border Collies and Kelpies will require lots of physical exercise, at least 2 hours each day, and mental stimulation as well.
2. Coping mechanism for anxiety or stress
Chewing can help dogs relieve anxiety or stress. Dogs suffering from separation anxiety or obsessive disorders may display this behaviour. Anxiety issues could also stem from boredom, lack of attention and adequate exercise. Take the time to identify the core problems leading to this behaviour and provide appropriate toys or long lasting treats for them to chew on. Talk to your vet and always seek professional help if your pet suffers with severe anxiety.
There are a number of ways to help manage your dog's anxiety at home. Find out more on how to calm an anxious pet. Anxiety aids, supplements or foods may be helpful, in combination with behavioural modification training which provides the most effective long term management.
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3. Enjoyment
Some pets may simply take a liking to chewing grass, whether it is the taste or texture, and they will eat for the enjoyment of it.
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
These diets contain fermentable prebiotic fibre, which helps to support a balanced gut microbiome plus a highly digestible formula promotes healthy digestion, ideal stool quality and reduced stool odour.
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:
Flea, Tick, Worming Guide for Dogs
Premium Pet Food, Is it Worth It?
Want to know more? Check out our Vet Tips Page for more tips on keeping your pets happy and healthy.