Why Is My Dog Eating Grass? 8 Reasons and When to Worry

You’re on a perfectly normal walk when your dog suddenly veers off the path, shoves their face into a patch of grass, and starts chomping like they haven’t eaten in days. Or maybe you’ve noticed them grazing in the backyard like a tiny, furry cow. Either way, it’s weird — and you’re wondering if something is wrong.

The short answer: dogs eating grass is extremely common, usually harmless, and not as well understood as you might expect. Veterinary researchers have studied this behavior for decades, and while we don’t have one definitive answer, we have several well-supported theories. Here are the eight most likely reasons your dog is eating grass, plus clear guidance on when it’s worth a vet visit.

1. It’s Normal Dog Behavior (Seriously)

The most important thing to understand is that grass-eating is a normal canine behavior, not necessarily a sign of a problem. A landmark study published in the journal Applied Animal Behaviour Science found that 79% of dogs with regular access to grass had eaten it at some point, and the vast majority of owners reported no signs of illness before or after.

Wild canids — wolves, coyotes, foxes — eat plant material regularly. Analysis of wild wolf scat frequently reveals grass and other vegetation. This suggests grass-eating isn’t a domestication quirk or a sign of nutritional deficiency — it’s an ancestral behavior that’s been part of the canine repertoire for thousands of years.

So before you panic about your dog’s backyard salad habit, know that it’s probably the most normal “weird” thing they do.

2. They Like the Taste or Texture

Sometimes the simplest explanation is the correct one. Many dogs appear to genuinely enjoy eating grass, especially young, tender shoots in spring when the grass is sweet and moist. They seek out specific patches, chew slowly and deliberately, and show every sign of savoring the experience.

This is different from the frantic, urgent grass-eating that sometimes precedes vomiting (more on that below). The leisurely grazer is a dog who’s found a snack they enjoy. It’s roughly equivalent to you eating celery — it’s not the most nutritious choice, but it tastes good and it’s not hurting anything.

Dogs that eat grass for enjoyment typically:

• Select specific grass types or patches
• Chew slowly rather than gulping
• Show no signs of stomach distress before or after
• Do it more frequently in spring when grass is fresh
• Seem relaxed and content during the behavior

3. Dietary Fiber Needs

Grass is primarily cellulose fiber, and some researchers believe dogs may eat it to supplement the fiber content of their diet. Modern commercial dog foods, especially grain-free formulas, may not always provide optimal fiber levels for every individual dog.

Fiber plays several important roles in canine digestion:

• Promotes regular bowel movements by adding bulk to stool
• Feeds beneficial gut bacteria that support intestinal health
• Slows digestion to improve nutrient absorption
• Creates a feeling of fullness that helps with weight management

If your dog eats grass regularly, consider whether their food provides adequate fiber. Check the guaranteed analysis on the bag — crude fiber should typically be between 3–5% for most adult dogs. Dogs on very low-fiber diets may instinctively seek out grass as a supplement.

Some owners report that adding a fiber source to their dog’s diet — like canned pumpkin (plain, not pie filling), steamed green beans, or a fiber supplement — reduces or eliminates grass-eating behavior. If fiber is the motivator, providing a better source addresses the root cause.

4. Stomach Upset and Self-Medication

This is the theory most people jump to, and while it’s real, it’s less common than people think. Some dogs do eat grass specifically to induce vomiting when they feel nauseous. The rough texture of grass blades can tickle the throat and stomach lining, triggering the gag reflex.

Dogs that eat grass to settle their stomach typically look different from casual grazers:

• They eat urgently and frantically, gulping large amounts quickly
• They show signs of stomach discomfort before eating (lip-licking, drooling, restlessness)
• They often choose longer, broader grass blades
• They may vomit within minutes of eating
• They seem relieved after vomiting and stop eating grass

However, research shows that fewer than 25% of dogs vomit after eating grass, which suggests that self-medication for nausea is not the primary motivation for most grass-eaters. If your dog consistently vomits after eating grass, it’s worth paying attention — but occasional grass-eating without vomiting is not a sign of chronic stomach problems.

5. Boredom and Understimulation

Dogs that don’t get enough physical exercise, mental stimulation, or social interaction may eat grass simply because it’s something to do. Chewing and foraging behaviors are self-reinforcing — they provide mild psychological satisfaction even when the dog isn’t hungry.

Boredom-related grass-eating is more likely if your dog:

• Spends a lot of time alone in the yard
• Doesn’t get daily walks or active play sessions
• Has few toys or enrichment activities
• Shows other boredom behaviors (digging, chewing furniture, excessive barking)
• Eats grass more on days when they’ve had less activity

If you suspect boredom is the cause, the solution isn’t to stop the grass-eating — it’s to address the underlying lack of stimulation. Longer walks, puzzle feeders, training sessions, playdates with other dogs, and interactive toys can all reduce boredom behaviors, including grass-eating.

6. Anxiety and Stress

Similar to boredom but with a different emotional driver, some dogs eat grass as a stress-coping mechanism. Repetitive chewing behaviors can be self-soothing, releasing calming neurochemicals that help an anxious dog manage their emotional state.

Anxiety-related grass-eating may accompany:

• Separation anxiety when left alone
• Noise phobias (thunderstorms, fireworks)
• Changes in routine or environment
• Introduction of new pets or family members
• Lack of confidence or generalized anxiety

If your dog’s grass-eating coincides with known stressors or anxiety triggers, addressing the anxiety is more productive than worrying about the grass. Consult with your veterinarian or a certified animal behaviorist about anxiety management strategies, which may include behavior modification, environmental changes, or medication.

7. Nutritional Deficiency

While less common than people assume, nutritional deficiencies can drive unusual eating behaviors, including grass consumption. This is a form of pica — the compulsive eating of non-food items — driven by the body’s attempt to obtain missing nutrients.

Potential deficiency-related triggers include:

• Inadequate micronutrients in low-quality dog foods
• Malabsorption issues where the dog isn’t properly absorbing nutrients from food
• Parasitic infections that steal nutrients from the digestive tract
• Chronic illness that increases nutrient demands

If your dog is on a well-balanced, AAFCO-compliant diet and is otherwise healthy, nutritional deficiency is unlikely to be the reason for grass-eating. However, if they eat grass obsessively, eat other non-food items (dirt, rocks, fabric), have a dull coat, low energy, or abnormal stools, a vet visit for bloodwork and nutritional assessment is warranted.

8. Instinctive Purging of Intestinal Parasites

An evolutionary biology theory suggests that grass-eating may be an inherited parasite-control mechanism. In wild canids, eating fibrous plant material increases intestinal motility and can physically wrap around and help expel intestinal worms.

Modern domestic dogs obviously have much lower parasite loads than their wild ancestors, but the instinct may persist as a vestigial behavior — similar to how dogs circle before lying down even on a flat, predator-free bed.

This theory is supported by research on wild chimpanzees, who swallow rough leaves whole to physically sweep parasites from their intestinal walls. Whether dogs are doing the same thing is debated, but it’s a plausible evolutionary explanation for why the behavior is so widespread across canid species.

When Grass-Eating Is Dangerous

While grass-eating itself is usually harmless, there are situations where it can cause problems:

Pesticides and Herbicides

This is the biggest concern. Grass treated with pesticides, herbicides, fertilizers, or weed killers can be toxic to dogs. Symptoms of chemical ingestion include:

• Excessive drooling
• Vomiting and diarrhea
• Lethargy
• Tremors or seizures
• Loss of appetite

Avoid letting your dog eat grass in areas that may be chemically treated — especially lawns with “recently treated” signs, golf courses, public parks during maintenance seasons, and neighbors’ yards where you don’t know what’s been applied.

Your own yard is only safe if you know exactly what’s been used on it. Many common lawn care products are toxic to dogs. If you want to let your dog graze safely, switch to pet-safe lawn care products or designate a chemical-free patch of yard for your dog.

Toxic Plants Mixed In

What looks like grass may include plants that are harmful to dogs. Certain weeds, mushrooms, and ornamental plants that grow in or near grass can be toxic. Common culprits include:

• Wild mushrooms (some are extremely toxic)
• Foxtail grass (the barbed seeds can lodge in ears, nose, and throat)
• Clover treated with herbicide
• Various ornamental plants near lawn edges

Supervise your dog when they eat grass and know what else is growing in the area.

Intestinal Obstruction

Dogs that eat very large quantities of grass can, in rare cases, develop a gastrointestinal obstruction. The grass forms a compacted mass that can’t pass normally through the intestines. This is uncommon in casual grazers but can happen with obsessive eaters.

Signs of obstruction include persistent vomiting, loss of appetite, abdominal pain, lethargy, and inability to pass stool. This is a veterinary emergency.

Parasite Transmission

Grass can carry parasite eggs — hookworms, roundworms, and whipworms — deposited by other animals. Dogs on regular parasite prevention are generally protected, but keeping your dog’s deworming schedule current is especially important if they eat grass regularly.

When to Talk to Your Vet

Occasional, casual grass-eating in a healthy dog doesn’t need veterinary attention. But you should make an appointment if:

• Your dog vomits frequently after eating grass — this could indicate an underlying GI issue
• The behavior is new and sudden — abrupt changes in behavior warrant investigation
• Your dog is eating grass obsessively — constant, compulsive eating suggests an underlying medical or behavioral condition
• You notice other symptoms — lethargy, weight loss, diarrhea, changes in appetite, or eating other non-food items
• Your dog may have eaten chemically treated grass — seek immediate veterinary care if you suspect chemical ingestion
• The grass-eating interferes with walks — if you can’t walk your dog without them spending the entire time eating grass, something may be off

Your vet can run bloodwork and a fecal exam to rule out nutritional deficiencies, parasitic infections, and underlying digestive disorders.

How to Reduce Grass-Eating (If You Want To)

If your dog’s grass-eating bothers you or you’re concerned about chemical exposure, here are some strategies:

Increase dietary fiber. Add a tablespoon of plain canned pumpkin to their food, or switch to a higher-fiber dog food. If fiber was the motivation, this often resolves it.

Provide more enrichment. Longer walks, food puzzles, training games, and chew toys give your dog better outlets for oral fixation and foraging instincts.

Offer safe alternatives. Cat grass or wheatgrass grown indoors gives your dog a safe, chemical-free option to satisfy their plant-eating urge. Many pet stores sell cat grass kits that work perfectly for grass-loving dogs.

Train a “leave it” command. Teaching a reliable “leave it” gives you the ability to redirect your dog away from grass in areas where it might be treated or unsafe. Reward them with a high-value treat for ignoring the grass.

Maintain a safe grazing area. If your dog is going to eat grass regardless, give them a designated spot in your yard that’s free from chemicals and known toxic plants.

Frequently Asked Questions

Is it okay to let my dog eat grass every day?

If the grass is free of pesticides and toxic plants, and your dog isn’t vomiting regularly, daily grass-eating is generally fine. It’s a normal behavior for most dogs and doesn’t indicate a problem by itself.

Does eating grass mean my dog is sick?

Usually not. The vast majority of grass-eating dogs are perfectly healthy. Illness-driven grass-eating is typically accompanied by other symptoms like vomiting, lethargy, changes in appetite, or abnormal stool. If grass-eating is the only unusual thing your dog is doing, they’re almost certainly fine.

Should I switch my dog’s food if they eat grass?

Not necessarily. If your dog is on a high-quality, AAFCO-compliant food and is otherwise healthy, the grass-eating probably isn’t diet-related. However, if you’re feeding a low-fiber diet and your dog grazes frequently, trying a food with higher fiber content or adding a fiber supplement is a reasonable experiment.

Why does my dog eat grass and then throw up?

Some dogs eat grass specifically because they feel nauseous, using the rough texture to trigger vomiting and relieve their discomfort. If this happens occasionally, it’s not alarming. If it happens frequently (more than once a week), see your vet — the nausea has an underlying cause that should be investigated.

Can puppies eat grass?

Puppies eat grass for the same reasons adult dogs do, and it’s generally safe as long as the grass hasn’t been treated with chemicals. However, puppies are more vulnerable to parasites transmitted through contaminated grass, so keeping their deworming schedule up to date is especially important.

My dog only eats grass in spring. Is this normal?

Very normal. Spring grass is tender, sweet, and more palatable than mature summer or fall grass. Many dogs that show no interest in grass most of the year become enthusiastic grazers when new growth appears. This strongly supports the “they just like the taste” theory.

The Bottom Line

Your dog eating grass is, in the vast majority of cases, nothing to worry about. It’s a natural behavior rooted in canine ancestry, and it can be motivated by anything from genuine enjoyment to fiber needs to mild stomach upset.

The key is context. A happy, healthy dog that occasionally nibbles on grass during walks is being a normal dog. A dog that frantically devours grass and vomits regularly, or that obsessively eats grass to the exclusion of other activities, may have an underlying issue worth investigating.

Keep your yard free of chemicals, stay current on parasite prevention, and let your dog be a dog. Some of them just like salad.