Why Does My Dog Eat Grass and Poop? (Pica and Coprophagia Explained)

Eating grass (pica in its mildest form) and eating feces (coprophagia) are two of the most commonly reported dog behaviors. Both behaviors have biological and behavioral explanations, though they are often misunderstood by owners.

This article explains the main causes of each behavior and outlines practical strategies for reducing or eliminating them.

Mystery 1: Why Do Dogs Eat Grass?

A commonly held belief is that dogs eat grass to make themselves vomit when they feel sick. The Truth: Studies show that fewer than 25% of dogs vomit after eating grass, and only 10% show signs of illness beforehand. Most dogs graze happily and keep it down.

The Real Reasons for Grazing:

1. They Like the Taste: Fresh spring grass is full of sugar and moisture. It has a satisfying crunch. To many dogs, it is simply a salad bar.
2. Fiber Deficiency: Some studies suggest dogs crave roughage to help digestion.
3. Boredom: “I am in the yard. Nothing is happening. I guess I will mow the lawn.”
4. Ancestral Instinct: Wolves eat the stomach contents of their prey, which usually consists of fermented grass, berries, and plants.

Should you stop it? Generally, no. Unless the grass has been treated with chemical fertilizers, pesticides, or herbicides (which are toxic and cause cancer), grazing is a harmless, natural behavior.

Mystery 2: Why Do Dogs Eat Poop? (Coprophagia)

This one is harder to stomach. Watching your dog eat their own stool (autocoprophagia) or another dog’s stool (allocoprophagia) is baffling. But biology offers some clues.

1. The “Mother” Instinct

Mother dogs instinctively eat their puppies’ poop to keep the den clean and hide the scent from predators. It is a hard-wired survival mechanism.

• The Habit: Some puppies mimic their mother. If not corrected, this “cleaning” habit can persist into adulthood.

2. Nutritional Deficiency (Malabsorption)

If a dog isn’t digesting their food properly, their poop essentially comes out looking (and smelling) just like it went in. To a dog, it still smells like food because it is partially undigested food.

• Medical Red Flags: If an adult dog suddenly starts eating poop, see a vet. It could be Exocrine Pancreatic Insufficiency (EPI) (where the pancreas fails to produce enzymes), Parasites (worms stealing nutrients), or Thyroid issues causing voracious hunger.

3. The “Forbidden Snack” (Cat Poop)

To a dog, the litter box is a vending machine of “Almond Rocas.”

• Why: Cat food is much higher in protein and fat than dog food. Therefore, cat poop is high in protein and fat. It is a high-value treat.
• The Fix: This is rarely behavioral; it’s opportunity. Put the litter box behind a baby gate or on a raised surface.

4. Attention Seeking

When the owner runs toward the dog to stop the behavior, the dog receives attention — even negative attention is reinforcing. The dog learns that eating poop produces an immediate, excited response from the owner.

• The Lesson: Even negative attention functions as a reward and can reinforce the behavior.

How to Stop Coprophagia

1. The Management Strategy (Immediate Cleanup)

This is the only 100% cure. If there is no poop in the yard, they cannot eat it.

• Pick up immediately after they go. Do not leave it for “later.”
• On walks, keep their head up and reward them for looking at you.

2. Dietary Deterrents

You can add things to their food that makes the poop taste bad (worse?).

• Pineapple / Zucchini: Contains enzymes that reportedly change the taste of the stool.
• Commercial Chews: Products like Coprophagia deterrents (usually containing MSG, chamomile, or parsley) aim to make the stool bitter.
• Meat Tenderizer: Sprinkling unseasoned meat tenderizer on food is an old breeder trick.

3. Training “Leave It”

This is a life-saving command.

• The Game: Put a low-value treat on the floor. Cover it with your hand. Say “Leave It.” Wait for them to stop sniffing your hand. The moment they back away, click and give them a high-value treat from your other hand.
• The Goal: “Leave It” means “Ignore that thing on the ground, and you will get something better from me.”

4. The Basket Muzzle

If your dog is obsessed and scavenges on walks (eating poop, dead animals, or trash), a Basket Muzzle (like a Baskerville) is a humane management tool. It allows them to pant, drink, and take treats, but the grid prevents them from picking up waste. It protects them from parasites like Giardia and worms.

When It’s Pica (Eating Rocks, Socks, Metal)

Eating poop is gross. Eating socks is deadly. Pica is the compulsion to eat non-food items.

• The Danger: Intestinal blockage. A sock cannot pass through the gut. It requires emergency surgery.
• The Cause: Often anxiety, OCD, or severe gastrointestinal disease (IBD).
• Action: If your dog eats objects, this is beyond “training.” You need a veterinary behaviorist and strict management (crating/muzzling) to keep them alive.

Frequently Asked Questions (FAQ)

Is coprophagia dangerous for my dog? Usually, eating their own fresh poop is harmless, though very unpleasant. However, eating the stool of other dogs or wild animals is highly dangerous because it can transmit internal parasites (like roundworms, hookworms, and giardia) or infectious diseases (like parvovirus).

Does feeding my dog more stop them from eating poop? Not necessarily, unless they have a genuine medical deficiency or malabsorption issue. If the behavior is rooted in anxiety, boredom, or a learned habit from puppyhood, increasing their portion sizes won’t stop the behavior and will likely just lead to unhealthy weight gain. Focus on training and environmental management instead.

Summary

• Grass: Fine, as long as it’s chemical-free.
• Poop: Gross, but usually behavioral. Clean the yard faster.
• Rocks/Socks: Medical emergency. See a vet.

Coprophagia is a manageable behavior. The most reliable solution is immediate cleanup to eliminate the opportunity. Training “Leave It” and using dietary deterrents address the behavior itself. When an adult dog suddenly begins eating feces, a veterinary examination is warranted to rule out nutritional malabsorption, parasites, or other medical causes.