Why Does My Dog Eat Grass? Causes and Solutions

You're on a walk, and your dog suddenly becomes very interested in eating the lawn like they're grazing cattle. A few bites later, they vomit. Or maybe they don't. Either way, you're wondering—why?

The grass-eating mystery is one of the most common questions vets receive. Here's what we know.

Is Eating Grass Normal?

Yes, for most dogs. Studies show 68-79% of dogs eat plants regularly, with grass being the most common choice. The AKC confirms that occasional grass eating is considered normal canine behavior.

Eating grass is typically:

• Not harmful
• Not a sign of illness
• Just... something dogs do

But the WHY is still being figured out.

Theories: Why Dogs Eat Grass

Theory 1: Upset Stomach

The popular belief: Dogs eat grass to vomit when they feel sick.

The reality: Only about 25% of dogs vomit after eating grass, and fewer than 10% show signs of illness before eating it.

So while some dogs may self-medicate, most grass-eating DOESN'T result in vomiting and doesn't seem illness-related.

Theory 2: Nutritional Deficiency

The idea: Dogs crave grass because they're missing fiber or nutrients.

The evidence: Mixed. Some studies suggest high-fiber diets reduce grass eating. But well-fed dogs with balanced diets still eat grass regularly.

Possible partial truth: Adding fiber may help some grass-eaters, but it doesn't explain the behavior in all dogs.

Theory 3: Instinctive Behavior

The theory: Dogs inherited grass-eating from wild ancestors who ate plant matter in prey's stomachs.

Wolves and wild canids do eat plant material. Grass-eating may be hardwired from ancestors who:

• Consumed prey intestinal contents
• Used plant matter for digestive health
• Purged parasites

This "ancestral diet" theory suggests grass-eating is normal canine behavior, not a problem to solve.

Theory 4: Boredom or Anxiety

The idea: Grass-eating is a displacement behavior.

Some dogs eat grass when:

• Understimulated
• Anxious
• Stressed

If your dog grazes excessively or compulsively, this may be a factor.

Theory 5: They Just Like It

Simple truth: Some dogs like the taste or texture.

Fresh spring grass, in particular, seems attractive to many dogs. They may simply enjoy it.

When Grass-Eating Is a Problem

Most grass-eating is benign, but watch for:

Excessive Consumption

Eating large amounts of grass frequently could indicate:

• Gastrointestinal issues
• Anxiety or compulsive behavior
• Dietary issues

Always Vomiting After

If your dog consistently eats grass and vomits, they may have:

• Underlying stomach issues
• Acid reflux
• Gastrointestinal disease

A vet check is worthwhile.

Treated Grass

This is the real danger. Grass treated with:

• Pesticides
• Herbicides
• Fertilizers

...can be toxic. If your dog grazes on treated lawns, this is a problem.

Parasites and Contamination

Grass can contain:

• Intestinal parasite eggs
• Feces from infected animals
• Bacteria

Regular deworming and keeping your dog's area clean helps.

When to See a Vet

Consult your veterinarian if:

• Your dog suddenly starts eating grass obsessively
• They vomit every time they eat grass
• There are other symptoms (lethargy, diarrhea, weight loss)
• They're eating non-food items beyond grass (pica)
• Behavior changes accompany grass-eating

These could indicate underlying medical issues.

What You Can Do

Safe Grass Access

If your dog eats grass, provide safe options:

• Untreated lawn areas
• Dog grass kits (grow your own indoors)
• Designated grazing spots you control

Increase Fiber

Try:

• Adding vegetables to diet (carrots, green beans)
• High-fiber dog food
• Fiber supplements (psyllium, pumpkin)

Some dogs reduce grass-eating with more dietary fiber.

Rule Out Boredom

If anxiety or boredom might be the cause:

• More exercise
• Mental enrichment
• Interactive toys
• Quality time with you

Check Diet Quality

Ensure your dog's diet is:

• Complete and balanced
• Age-appropriate
• High quality

Poor diets may increase grass-seeking behavior.

Avoid Treated Lawns

• Know if your lawn is treated
• Avoid parks/neighbors' lawns after treatment
• Wait for recommended time after lawn applications
• Rinse paws after walks

Redirect the Behavior

If you want to stop grass-eating:

• Teach "leave it"
• Redirect to a toy or treat
• Keep them on leash in grass-heavy areas

But remember—moderate grass eating is normal and often not worth fighting.

Types of Grass Dogs Prefer

Not all grass is equal:

• Fresh, young grass is most attractive
• Tall grass may be preferentially grazed
• Spring grass (new growth) seems especially appealing

Some dogs ignore grass entirely while others are dedicated grazers.

Other Things Dogs Eat (And Shouldn't)

If your dog eats grass, they may also eat:

• Sticks (risk of splinters and obstruction)
• Mulch (some types toxic)
• Rocks (serious obstruction risk)
• Dirt (could indicate mineral deficiency)

These are more concerning than grass. "Pica" (eating non-food items) may require behavioral and medical intervention.

The Bottom Line

Most grass-eating is normal dog behavior:

• Not a sign of illness (usually)
• Not nutritionally necessary (probably)
• Not something you must stop

Be concerned if:

• It's excessive or compulsive
• They always vomit after
• Grass is treated with chemicals
• Other symptoms accompany the behavior

Otherwise, let your dog enjoy their salad. They've probably been doing it since before they were domesticated.

Related: Why Does My Dog Chase His Tail? Related: Understanding Dog Behavior

Frequently Asked Questions

Should I stop my dog from eating grass?

If the grass is untreated (no pesticides, herbicides, or fertilizers) and your dog isn't vomiting excessively afterward, occasional grass eating is generally harmless and can be left alone. The main risks come from chemically treated lawns, grass contaminated with other animals' feces, or areas where toxic plants grow alongside the grass. If your dog eats grass compulsively or always vomits afterward, consult your vet to rule out gastrointestinal issues.

Does eating grass mean my dog has a nutritional deficiency?

While this is a popular theory, research hasn't found a strong link between grass eating and nutritional deficiencies in dogs on balanced commercial diets. Most grass-eating dogs are well-nourished and eat grass simply because they enjoy the taste or texture. However, if your dog suddenly starts eating large amounts of grass along with other changes like weight loss or dull coat, a vet checkup to review their diet and health is worthwhile.

Why does my dog eat grass and then throw up?

Only about 25% of dogs that eat grass vomit afterward, and it's unclear whether they eat grass because they feel nauseous or if the grass tickles their throat and triggers vomiting. Some dogs may instinctively eat grass to induce vomiting when they have an upset stomach, but many grass-eaters never vomit at all. If your dog frequently eats grass followed by vomiting, or if the vomit contains blood or bile, schedule a vet visit to check for underlying digestive problems.