FirstVet
Black dog with tongue out

Why is my dog eating grass and vomiting?

Many dogs eat grass from time to time, and some will also vomit as a result. For a dog owner, it can be confusing to understand why your dog eats grass, especially as it appears to make him or her sick. In this article our vet discusses the reasons behind this common behaviour.

This article was written by a FirstVet vet


Did you know that FirstVet offers video calls with experienced, UK registered vets? You can get a consultation within 30 minutes by downloading the FirstVet app for free from the Apple App Store or Google Play.


✓ Included free as part of many pet insurance policies
✓ Help, treatment and if you need it, a referral to your local vet
✓ Open 24 hours a day, 365 days a year

This article will cover:

  • Why do dogs eat grass?

  • If my dog is eating grass does this mean they are unwell?

  • What precautions do I need to take if my dog eats grass?

Why do dogs eat grass?

Pica is the medical term for eating things that aren’t food such as grass. In most cases eating grass is not harmful and many vets consider this to be normal dog behaviour. It is most likely that dogs eat grass because fresh grass tastes good! Grass and plant material have been found in the stomach contents of wild canids such as wolves, and dogs may have inherited this behaviour from their wild ancestors. Young dogs tend to eat grass or plants more often than older animals and this may be a way of developing foraging behaviours as a puppy investigates its environment.

Dogs can vomit for a variety of reasons. Common causes include infections in the gastrointestinal tract, food changes, especially those that are made too quickly, food sensitivity, dietary indiscretion, and other more serious gastrointestinal diseases. Remember to use a regular anti-parasite treatment to prevent intestinal worms and diseases such as lungworm that are caused by the accidental ingestion of slugs and snails.

If my dog is eating grass does this mean they are unwell?

Many owners think that eating grass is a sign of illness or nausea. In most cases this is not the case. However, eating grass can lead to vomiting and in some cases dogs may be eating grass to make themselves sick. Some owners say that their dog only eats grass after showing signs of illness or not feeling well and vomits bile afterward. If this happens on the odd occasion and your dog seems to be better afterwards then it is unlikely to be something to worry about.

If your dog is vomiting regularly or repeatedly we would advise talking to your vets to rule out any other causes of vomiting. You can find out more about vomiting in dogs here.

What precautions do I need to take if my dog eats grass?

If your dog does eat grass then it is important to keep them away from grass or plants that may have been treated with harmful chemicals. It is also important to ensure that they have been treated against lungworm. Dogs can become infected by lungworm after accidentally eating slugs, snails or the slime trail. Lungworm can have serious health implications. You can find out more about lungworm and how to prevent it here.

Bilious Vomiting Syndrome (BVS)

If you can notice that your dog often vomits bile in the mornings, or when they have not eaten for a long period between meals, this is likely to be caused by biliary vomiting syndrome (BVS). This occurs when the digestive fluids in the intestine overflow back into the stomach causing irritation and subsequent vomiting.BVS is often easily resolved by giving your dog smaller and more frequent meals during the day. Try feeding a small meal last thing at night, so that your dog will have something to digest in its intestine until breakfast, or the next meal. We recommend starting with a highly digestible complete diet, such as Purina EN, or cooked rice or pasta with chicken, white fish, turkey or egg

When to visit your vet

  • If your dog is eating grass constantly or repeatedly

  • If your dog is vomiting regularly or you see blood in the vomit.

  • If your dog is showing signs of being unwell such as fever, lethargy, inappetence

Further information

Vomiting and diarrhoea in dogs

Still worried?

Book a video appointment to have a chat with one of our vets.

More articles about Dog