Who hasn’t wondered, “Why does my pet eat grass?” The truth is there isn’t one clear reason. What we do know is that eating small amounts of grass can be a harmless, albeit curious, thing for a perfectly healthy dog or cat to do. But when nibbling turns into gulping great hunks of the stuff — and grassy vomit hits the kitchen tile — it’s time to wonder what’s going on.


Your vet may consider several reasons your pet is eating grass, including these:

1. Behavioral drives. Pica is a word used to describe eating things that do not serve a biologic or nutritional purpose — such as when a pet eats paper or plastic. It may be that the behavior feels good or there is some other behavioral reason. But a medical issue, such as a neurologic disease, can cause pica, so it shouldn’t be completely written off without discussing with your vet.

2. Nutritional cravings. Even though a dog or cat may be eating a nutritionally complete diet, that doesn’t mean that cravings for certain things (such as grass) don’t occur.

3. Idiopathic causes. Idiopathic means simply that the veterinarian doesn’t know the exact cause. But you should continue to watch the situation.

What To Do at Home

Owners who observe their pets frequently nibbling grass probably don’t need to rush to the emergency room. Rather, they should watch their pets to gain more information about the grass eating. Ask yourself:

  • Does my pet eat grass voraciously?
  • Does he vomit or feel sick afterward?
  • Is there pattern? For example, does it also happen on days when he doesn’t eat all of his food?
If you answer no to the first two, there’s probably no need to raise the issue with your veterinarian. If the answer to either is yes, it’s worth paying attention to No. 3.

Armed with this information, owners can then present their findings to their veterinarians.

What Your Veterinarian Will Do

Your pet’s doctor will begin looking for a medical condition at work in the grass consumption. The goal is to figure out if it is a sign of a minor ailment, a more serious disease, or nothing more than normal albeit slightly eccentric behavior.

Normally the vet will start with the least invasive test and move on to more expensive, more invasive tests as needed (which will depend on the severity of the symptoms). From least to most invasive:

  • Fecal examination (to check for parasites)
  • Blood work: CBC, blood chemistry
  • Urinalysis
  • X-rays
  • Abdominal ultrasound
  • Barium study (a type of x-ray study for examining the intestinal tract)
  • CT scan
  • Endoscopy with biopsies
  • Exploratory laparoscopy with biopsies
Few grass-eaters are likely to have ever suffered an exploratory laparoscopy to surgically look into the contents of an abdomen and biopsy the gastrointestinal tract, but severe symptoms could theoretically lead a veterinarian to decide this is the best approach.

Not every grass-eater has a serious medical problem, though. For many pets who want to sample the lawn, the prescription may be to let them go right ahead. Just make sure the grass is not treated with any chemicals that could be harmful if your pet eats them.

This article was written by a Veterinarian.