Why Do Dogs Eat Grass and Vomit?

Dogs may sometimes eat grass and vomit, and many pet parents assume this behaviour means their dog is trying to soothe an upset stomach. While it’s possible that a nauseous dog may feel some relief after throwing up — much like people do — grass eating isn’t always about illness.

There are several theories about why dogs graze on grass. Some experts believe it may help add fibre to the diet, others think it’s instinctual, and some dogs simply seem to enjoy the taste and texture.

If you’re wondering, “Why do dogs eat grass and vomit?”, you’re not alone. Dogs and humans may share a special bond, but sometimes our canine companions behave in ways that leave us scratching our heads.

The reassuring news: occasional grass eating is usually normal and nothing to worry about. It’s a common canine behaviour, even though the exact reason behind it is still unclear.

Why Do Dogs Eat Grass?

No one knows with certainty why dogs eat grass, but several theories help explain the behaviour.

1. Nausea

A widespread belief is that dogs eat grass to make themselves vomit when they feel unwell. However, research suggests the connection is weaker than many assume.

According to the Veterinary Centers of America:

• fewer than 25% of dogs actually vomit after eating grass
• only around 10% show any signs of illness beforehand

While stomach upset is a common cause of vomiting in dogs — and green vomit may indicate grass ingestion — other triggers, such as sudden diet changes, are more common reasons for digestive upset.

2. They Enjoy the Taste

Some dogs simply like the taste or texture of grass. As descendants of wolves, dogs retain omnivorous tendencies and may graze the way their ancestors foraged in the wild.

3. Nutritional Deficiencies

It’s often suggested that dogs eat grass to compensate for missing nutrients, particularly fibre. Grass is rich in fibre, an essential component of a healthy canine diet.

However, research has not proven a clear link between nutritional deficiencies and grass eating. If your dog is already eating a complete and balanced diet, it’s unlikely they’re grazing because something is missing.

If you’re concerned about dietary adequacy, speak with your veterinarian to ensure your dog is getting proper nutrition.

4. Boredom

Dogs that aren’t mentally or physically stimulated may turn to activities like:

• chewing
• digging
• grazing on grass

Daily exercise, interactive toys, enrichment games, and dedicated one‑on‑one time can reduce boredom‑related behaviours and improve overall well‑being.

5. An Evolutionary Behaviour

Another theory points back to a dog’s ancestral roots. Wild canids often consumed the entire body of herbivore prey, including stomach contents filled with grasses and plants.

Additionally, animals like foxes and wolves are known to eat berries and plant material directly. This suggests that grass eating may be an inherited behaviour rather than a sign something is wrong.

Is My Dog Sick if They Eat Grass and Vomit?

An occasional episode of a dog eating grass and vomiting is usually not a red flag — especially if they quickly return to normal behaviour.

However, contact your veterinarian if:

• the behaviour becomes frequent
• your dog throws up repeatedly in a short period
• there is a sudden change in appetite or energy
• your dog begins eating other non‑food items

Persistent ingestion of inedible objects may signal pica, a condition often linked to gastrointestinal disease. Dogs with pica may eat things like dirt, clothing, garbage, or rocks. Left untreated, pica can lead to serious digestive complications.

Can Dogs Eat Grass?

Yes — dogs can eat grass. It’s typically harmless unless:

• it’s excessive
• it represents a sudden behaviour change
• the grass has been treated with pesticides or chemicals
• poisonous plants are present nearby

Always ensure your yard is safe before allowing your dog to graze.

How to Stop a Dog From Eating Grass and Throwing Up

If you’re worried that grass eating is causing your dog to vomit, start by speaking with your veterinarian. They can help determine whether the behaviour is harmless or related to an underlying condition.

Potential solutions include:

1. Adjusting the Diet

If a nutritional issue is suspected, your vet may recommend a new food formula or gradual diet transition.

2. Supporting Digestive Health

Digestive supplements may help dogs with sensitive stomachs or mild nausea. Always consult your veterinarian before introducing new supplements.

3. Managing Anxiety

If grass eating stems from nervousness, calming aids or behavioural strategies may help.

4. Boosting Enrichment

More exercise, enrichment toys, puzzle feeders, or playtime in the yard can help redirect your dog’s attention away from grazing.

When to Call the Veterinarian

Seek veterinary care if:

• your dog eats large amounts of grass repeatedly
• vomiting continues or worsens
• your dog is lethargic, dehydrated, or not acting normally
• non‑food item consumption begins
• you’re simply unsure and want reassurance

Your veterinarian can assess your dog and rule out any underlying medical issues. For more insights into dog behaviour and health, explore additional articles on our Pet Expertise page.