Pet Connection: It’s mostly OK for dogs to graze on grass

Q: My dog loves to eat grass. She grazes so frequently that we have taken to calling her our little cow dog. Luckily, she doesn’t vomit it up. Why do dogs do this, and can it be harmful?

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A: I’ve met many dogs who enjoy nibbling on the green stuff with no ill effect. In most cases, eating small amounts of grass is a normal and acceptable behavior for dogs.

Dogs who frequently eat a lot of grass and then throw it up may benefit from a veterinary visit. A physical exam may bring to light the cause of an upset stomach, but sometimes we need further diagnostics. Blood work, a urinalysis and a stool sample to check for parasites can turn up problems that might relate to grass-eating. Some dogs may eat grass because their body is seeking some nutrient that’s not available in their diet.

Dogs are individuals, so some may have nutritional needs that are met with a little serving of grass. Can grass be harmful? Well, pets can ingest parasite eggs when they eat it, but as long as you give your dog parasite preventive regularly, that shouldn’t be a problem.

And, naturally, your dog should never nibble on grass that has been treated with herbicides, pesticides or other chemicals. Ingesting those substances isn’t good for any dog, of course, but certain breeds – Scottish terriers, Shetland sheepdogs, beagles, West Highland white terriers and wirehaired fox terriers – have a higher incidence of invasive transitional cell carcinoma, the most common cancer of the urinary bladder in dogs. That type of cancer has been linked to exposure to lawns treated with pesticides, insecticides and herbicides.

Dogs eat grass for lots of reasons, and the truth is, we don’t always know why. In your dog’s case, she may simply enjoy a nice salad once in a while.

Pet Connection is produced by a team of pet-care experts headed by veterinarian Dr. Marty Becker and Kim Campbell Thornton, author of many pet-care books. The two are affiliated with