Why Do Dogs Eat Grass?

Many dogs enjoy nibbling on grass, and while they may only spend a few minutes a day doing it, it can still cause concern for dog owners. When your dog starts munching on grass, you might worry about their health—especially if they vomit afterwards. Is it a sign of sickness or a poor diet? Let’s break down the reasons behind grass-eating and whether it’s something to worry about.

Is Grass-Eating a Sign of Illness?

A common worry is that dogs eat grass because they feel unwell. However, studies show that even healthy dogs with no digestive problems or parasites eat grass. In one study, dogs vomited after eating grass in only a few cases, suggesting that grass-eating isn’t necessarily linked to sickness. We may just notice it more when vomiting happens, which can lead us to assume the two are always connected.

If a dog is suffering with digestive discomfort, they may eat grass to help soothe gut irritation. When there’s inflammation or irritation in the digestive tract, eating grass might provide temporary relief. The fibrous texture of grass may help sweep through the digestive system, potentially moving irritants or undigested material along. Additionally, chewing on grass could stimulate saliva production, which helps neutralise stomach acid, or it might even act as a mild irritant to trigger vomiting, allowing the dog to expel whatever is causing discomfort.

Is Your Dog Missing Nutrients?

Another theory is that dogs eat grass to make up for missing nutrients in their diet. However, research shows that dogs fed all kinds of diets—whether it’s table scraps, commercial food, or raw food—still eat grass. So, it’s unlikely that grass-eating is due to a nutrient deficiency.

Some consider that dogs may eat grass partly because of chlorophyll, a green pigment in plants that supports their health. Chlorophyll is similar to haemoglobin, which helps carry oxygen in red blood cells. It has benefits like protecting cells, aiding digestion, and boosting the immune system. Since dogs don’t naturally consume green plants, grass can become a source of chlorophyll. However, it’s harder for dogs to digest than other leafy greens, so adding puréed or steamed vegetables like kale or broccoli to their diet may be more beneficial if you are concerned about their grass-eating behaviour.  

Could Grass Just Be a Quick Snack?

Some dogs tend to eat more grass before mealtime, especially in the morning. This suggests that dogs might eat grass simply because it’s available and they’re feeling a little hungry. Grass is easy to find, so it may just be a convenient snack for them.

Does Grass-Eating Help with Parasites?

Grass-eating may also be a behaviour passed down from wild canines. In the wild, dogs ate plants to help clear parasites from their system. Since plants are harder to digest, they can help move parasites out of the digestive tract. But this doesn’t mean your dog has worms—this is just a natural behaviour that’s stuck with them over time.

Why Do Puppies Eat More Grass?

Younger dogs tend to eat grass more often than older ones. Puppies explore the world through their mouths, but this behaviour could also be linked to their need to avoid parasites. In the wild, smaller animals are more affected by parasites, so grass-eating may be a survival instinct that’s stronger in younger dogs.

Is Eating Grass Harmful?

In most cases, eating grass isn’t harmful to dogs. However, if the grass has been treated with chemicals like weed killers (such as glyphosate), it can be dangerous. Chemicals like these can cause vomiting, diarrhoea, lethargy, and even breathing problems. So, it’s important to ensure your dog isn’t eating grass from treated areas.

Additionally, some plants are toxic to dogs. Sago palms, tomato plants, daffodils, and other common plants can be harmful if eaten. Always check your yard and surroundings to make sure your dog isn’t chewing on something dangerous.

When Should I Be Concerned?

If your dog is frequently vomiting after eating grass or showing other signs of discomfort, it’s worth checking in with your vet. Occasional grass-eating is normal, but if your dog is vomiting regularly, it could indicate an underlying issue.

It’s also important to ensure that the grass your dog eats is free from chemicals and that they aren’t chewing on toxic plants.

The Bottom Line

Grass-eating is a natural behaviour in dogs and usually isn’t something to worry about. While it might seem strange, dogs have their reasons—whether it’s hunger, to settle their tummy, curiosity, or a throwback to their wild ancestors. Just keep an eye on what your dog is eating and make sure their environment is safe from harmful chemicals and plants.