Why Do Dogs Eat Poop? The Science Behind Coprophagia in Dogs
Why do dogs eat poop? Explore the evolutionary, physiological, and behavioral science behind coprophagia in dogs, plus practical solutions that work.
Quick Answer: Why Do Dogs Eat Poop?
Coprophagia — the scientific term for dogs eating feces — is a normal, evolutionarily rooted behavior observed in up to 25% of pet dogs at some point in their lives, according to a 2018 study published in Veterinary Medicine and Science. Dogs eat feces for multiple reasons: maternal den-cleaning instincts, scavenging drive inherited from wolves, nutritional curiosity, attention-seeking, or occasionally an underlying medical condition. While it is usually not dangerous, it warrants attention because it can spread parasites and bacteria. If the behavior is sudden or compulsive, consult your veterinarian to rule out malabsorption disorders, pancreatic insufficiency, or parasite loads.
The Science of Coprophagia: What Research Tells Us About Dogs Eating Feces
Key Study: UC Davis School of Veterinary Medicine (2018)
A landmark survey-based study conducted by Dr. Benjamin Hart and colleagues at the UC Davis School of Veterinary Medicine surveyed over 1,500 dog owners and found:
- 16% of dogs were classified as "frequent" poop eaters (observed doing it 6+ times)
- 24% of dogs had been observed eating feces at least once
- Dogs described as "greedy eaters" who bolted their food were significantly more likely to be coprophagic
- Breed mattered: Shetland Sheepdogs showed the highest incidence, while Poodles (standard and miniature) showed almost none
- Access to other dogs' feces was the strongest environmental predictor
- Commercial anti-coprophagia products had a success rate of only 0–2%, while environmental management and positive reinforcement training showed meaningfully better outcomes
This study challenged the long-held assumption that coprophagia is primarily driven by nutritional deficiency. Instead, it pointed toward an innate scavenging behavior hardwired into certain dogs' feeding strategies.
A 2012 study published in the journal Applied Animal Behaviour Science further found that coprophagic dogs did not differ significantly from non-coprophagic dogs in diet composition, suggesting that the behavior is not a compensatory response to missing nutrients in most cases. The Merck Veterinary Manual categorizes coprophagia under pica (consumption of non-food items) and notes that while nutritional causes should be ruled out, behavioral and instinctual drivers are far more common.
The Evolutionary Basis: Why Ancestral Canines Ate Feces
Ancestral Function of Coprophagia
In wild canids — wolves, coyotes, and African wild dogs — feces consumption serves specific survival functions. Understanding these helps explain why the behavior persists in domestic dogs thousands of years after domestication.
Den hygiene and predator avoidance. Lactating wolf and wild dog mothers consume the feces of their pups during the first three to four weeks of life. This serves a dual purpose: it keeps the den clean (reducing scent that predators could track) and recovers the significant caloric investment the mother has made in producing milk. Pups' digestive systems are immature, and their feces contain partially digested milk proteins and fats that the mother's body can reprocess. This behavior is so strongly conserved that even domestic dog mothers who have never been taught this behavior will perform it instinctively.
Scavenging ecology. Wolves and early proto-dogs were opportunistic scavengers. In lean periods, consuming the feces of herbivores provided access to partially broken-down plant material, B-vitamins produced by gut bacteria in the herbivore's digestive tract, and residual calories. This scavenging flexibility is one reason canids survived as a family while more specialized predators went extinct. Modern dogs retain this generalized feeding drive, which the UC Davis study linked to the "greedy eater" phenotype.
Social learning in pack environments. In wild canid groups, juveniles observe and sometimes imitate the feeding behaviors of adults, including coprophagia during den-cleaning. This social transmission means the behavior can persist in multi-dog households where one dog learns it from another — a pattern frequently reported by owners and confirmed in behavioral surveys.
How a Dog's Body and Brain Process the Drive to Eat Feces
The physiological mechanism behind coprophagia involves several interacting systems:
Olfactory processing. Dogs possess approximately 300 million olfactory receptors (compared to humans' ~6 million) and an olfactory bulb that is proportionally 40 times larger than ours. Feces contain a complex chemical profile — undigested proteins, bacterial metabolites, volatile fatty acids, and species-specific pheromonal markers. To a dog's olfactory system, feces are not "disgusting" the way human brains categorize waste. Instead, feces register as an information-rich stimulus that may signal the presence of food-derived compounds worth investigating orally.
Gustatory and oral exploration. Dogs explore their environment primarily through their mouths. The combination of a strong scent signal and oral-tactile curiosity creates a neurological pathway where investigation escalates to consumption. The vomeronasal (Jacobson's) organ, located in the roof of the mouth, further processes chemical signals from substances the dog mouths, reinforcing the feedback loop.
Dopaminergic reward pathways. When a dog consumes feces and finds it palatable (which is more likely if the feces contain undigested fats or proteins, as from a cat's litter box), the brain's reward system releases dopamine. This reinforces the behavior neurologically, making it more likely to recur. This is why coprophagia can become habitual even when the original trigger (e.g., maternal instinct, nutritional gap) has resolved.
Enzyme deficiencies and malabsorption. In some medical cases, the physiological driver is genuine. Dogs with exocrine pancreatic insufficiency (EPI) cannot produce adequate digestive enzymes, meaning their own feces contain high levels of undigested nutrients. The dog's body sends hunger signals despite adequate food intake, and the dog may consume its own feces in an attempt to recover calories. This is a medical condition requiring veterinary diagnosis through a trypsin-like immunoreactivity (TLI) test, typically costing $80–$150 at most veterinary labs.
Practical Implications: What Coprophagia Means for Your Daily Life
Actionable Strategies That Work
Based on the UC Davis findings and positive-reinforcement training protocols, here is a ranked framework for managing coprophagia:
| Strategy | Estimated Success Rate | Time to Results | Cost Range |
|---|---|---|---|
| Immediate cleanup (pick up feces within 2 minutes) | 90%+ (prevents opportunity) | Immediate | $0 |
| "Leave it" + positive reinforcement redirect training | 60–75% | 3–6 weeks | $0–$150 (trainer sessions) |
| Dietary enrichment (higher-fiber, slower-feed bowls) | 30–40% | 2–4 weeks | $10–$40/month |
| Commercial taste-aversion supplements (e.g., For-Bid, NaturVet) | 0–12% (per UC Davis data) | 2–4 weeks | $12–$30 |
| Veterinary workup (rule out EPI, parasites, malabsorption) | High if medical cause found (~10–15% of cases) | 1–2 weeks | $100–$350 (exam + labs) |
| Muzzle during outdoor access (management tool) | 95%+ (physical barrier) | Immediate | $15–$35 (basket muzzle) |
The most effective protocol combines three layers: immediate environmental management (pick up feces instantly), behavioral training ("leave it" cue reinforced with high-value treats like freeze-dried liver or chicken), and veterinary screening to rule out medical causes. This layered approach addresses the behavior from multiple angles without relying on any single intervention.
For cat litter box raiders: Cat feces are especially attractive to dogs because cats are obligate carnivores with high-protein diets, meaning their feces contain significant undigested protein and fat. Solutions include placing the litter box behind a baby gate with a cat-sized gap (typically 4–5 inches wide for most cats), using a top-entry litter box, or installing a microchip-activated cat door (such as the SureFlap Microchip Pet Door, ~$80–$120) that excludes the dog entirely.
Common Myths About Dogs Eating Poop — Debunked by Science
| Common Myth | What Science Shows |
|---|---|
| "Dogs eat poop because their diet is missing nutrients." | The UC Davis study found no significant dietary differences between coprophagic and non-coprophagic dogs. Nutritional deficiency is a cause in a minority of cases (primarily EPI and severe parasite loads), not the default explanation. |
| "Adding pineapple or meat tenderizer to food will stop it." | These home remedies have no peer-reviewed evidence supporting efficacy. The bromelain in pineapple and papain in meat tenderizer are broken down by stomach acid before they can alter fecal taste meaningfully. |
| "Only sick or poorly trained dogs eat poop." | Up to 25% of healthy, well-trained dogs exhibit this behavior at some point. It is an inherited scavenging trait, not a sign of training failure or illness in most cases. |
| "Dogs will outgrow it on their own." | Puppies often explore orally and may stop by 6–9 months, but dogs that develop habitual coprophagia past 12 months tend to continue without intervention. The UC Davis study found no age-related decline in established coprophagia. |
| "Punishment or scolding will stop the behavior." | Aversive methods can increase anxiety-driven compulsive behaviors and damage the human-dog bond. Positive reinforcement-based redirection is the recommended approach per the American Veterinary Society of Animal Behavior. |
Breed Variations and Individual Differences
The UC Davis study identified notable breed patterns, and veterinary behaviorists have observed additional trends across clinical practice:
Higher incidence breeds: Shetland Sheepdogs, Labrador Retrievers, Golden Retrievers, Beagles, and Terrier breeds show above-average rates. These breeds share traits of high food motivation, strong scavenging drives, or oral-exploratory tendencies. Labrador Retrievers, for example, carry a documented POMC gene mutation associated with increased food motivation and obesity risk, which may partly explain their elevated coprophagia rates.
Lower incidence breeds: Standard and Miniature Poodles, Greyhounds, and some toy breeds show below-average rates. Brachycephalic breeds (Pugs, Bulldogs) show mixed results — some individuals are highly food-motivated, but their shorter muzzles and breathing limitations may reduce the speed and frequency of oral investigation.
Multi-dog households: Dogs living with other dogs are more likely to exhibit coprophagia, likely due to social learning and increased fecal availability. In households where one dog is coprophagic, the probability of a second dog adopting the behavior increases by an estimated 40–60%.
When Coprophagia Signals a Medical Problem
When to Consult Your Veterinarian
Coprophagia is usually behavioral, but schedule a veterinary appointment if you observe any of these red flags:
- Sudden onset in an adult dog with no prior history of the behavior
- Weight loss despite normal or increased food intake
- Chronic diarrhea or unusually large, pale, greasy stools (signs of malabsorption)
- Vomiting after eating feces
- Increased appetite (polyphagia) combined with coprophagia
- Lethargy or coat deterioration alongside the behavior
Your vet will typically run a fecal flotation panel ($35–$60), a complete blood count and chemistry panel ($80–$150), and potentially a TLI test for pancreatic function ($80–$150). If parasites such as Giardia, roundworms, or hookworms are identified, deworming treatment typically costs $20–$60 and resolves both the parasite load and the coprophagia it may have triggered.
Zoonotic risk note: Dogs that consume feces — particularly from other species or from unknown sources in public areas — can acquire parasites transmissible to humans, including Toxocara canis (roundworm) and Ancylostoma (hookworm). Regular fecal screening every 6–12 months and consistent heartworm/intestinal parasite prevention (e.g., Interceptor Plus, Sentinel, or NexGard Combo — typically $15–$25/month) protect both your dog and your household.
Related Behaviors: How Coprophagia Connects to Other Canine Traits
Coprophagia does not exist in isolation. It overlaps with several other well-documented canine behaviors:
- Pica: The broader category of consuming non-food items (rocks, fabric, plastic). Dogs with pica may also exhibit coprophagia, and both warrant veterinary screening for nutritional or metabolic causes.
- Counter-surfing and food stealing: Dogs with high food motivation often exhibit multiple food-seeking behaviors. The same dopaminergic reward pathways drive both counter-surfing and coprophagia.
- Rolling in feces or carrion: This scent-masking behavior, also inherited from wild canids, involves similar olfactory attraction to fecal material but stops short of consumption.
- Geophagia (eating dirt or soil): Another pica variant that may indicate mineral deficiency, gastrointestinal upset, or simply oral exploration. Often seen alongside coprophagia in puppies.
- Grass eating: While technically consumption of plant material, grass eating is reported in 68% of dogs and is considered normal behavior, possibly aiding digestion or fulfilling a fiber need. It rarely causes concern unless accompanied by repeated vomiting.
Frequently Asked Questions
Why do dogs eat their own poop?
Dogs eat their own feces due to a combination of inherited scavenging instincts, oral-exploratory behavior, and sometimes medical conditions like exocrine pancreatic insufficiency or intestinal parasites. Puppies often experiment orally and may stop naturally, but habitual coprophagia in adult dogs is typically driven by strong food motivation and learned reinforcement.
Can dogs get sick from eating poop?
Yes. Consuming feces from other dogs or animals can transmit intestinal parasites (roundworms, hookworms, whipworms, Giardia), bacteria (Salmonella, E. coli, Campylobacter), and viruses (parvovirus can survive in feces for months in the environment). Dogs that eat horse or livestock feces risk exposure to deworming medication residues (ivermectin), which can be toxic at high doses, particularly in MDR1 gene-mutation breeds like Collies and Australian Shepherds. If your dog ingests unknown feces and shows vomiting, diarrhea, or lethargy, contact your veterinarian or the ASPCA Animal Poison Control Center at (888) 426-4435 (24/7, consultation fee applies).
How do dogs process the smell of feces differently from humans?
Dogs have roughly 50 times more olfactory receptors per unit of nasal tissue than humans and a proportionally much larger olfactory bulb. Where a human brain categorizes fecal odor as a disgust response (an evolved pathogen-avoidance mechanism), a dog's brain processes fecal odor as a complex chemical signal containing information about diet, health status, identity, and potential food content. The "disgust" emotion is a primate adaptation; dogs do not experience it in relation to feces.
What does it mean when my dog eats cat poop from the litter box?
Cat feces are particularly attractive to dogs because cats are obligate carnivores that consume high-protein, high-fat diets. Their digestive systems process food quickly, and their feces retain significant undigested protein and fat. This makes cat feces essentially a "high-value treat" from the dog's perspective. The behavior is so common that veterinary behaviorists sometimes refer to it as a distinct subcategory. Management solutions focus on physical barriers rather than taste aversion, since the palatability of cat feces is very high.
Is coprophagia normal in puppies?
Yes, oral exploration including brief coprophagia is considered developmentally normal in puppies between 4 and 9 months of age. Puppies explore their environment orally the same way human infants use their hands. Most puppies stop this behavior naturally as they mature, particularly if owners consistently remove feces from the environment and redirect the puppy's attention with appropriate chew toys and training. However, if the behavior persists past 12 months or intensifies, it is more likely to become a habitual pattern requiring active intervention.
How is canine coprophagia different from the same behavior in humans?
In humans, coprophagia is considered pathological and is almost exclusively associated with severe psychiatric or neurological conditions. In dogs, it is a species-typical behavior with evolutionary precedent, observed across healthy populations at rates of 16–25%. The key difference is that human disgust responses to feces are a highly developed pathogen-avoidance adaptation, while dogs lack this specific emotional pathway and instead process fecal material through their scavenging and olfactory investigation systems. This fundamental neurological difference means that "disgust-based" training approaches (such as applying hot sauce or bitter sprays to feces) are less effective with dogs than environmental management and positive reinforcement.
Sources
- Hart, B.L., et al. (2018). "The paradox of canine conspecific coprophagy." Veterinary Medicine and Science, 4(2), 106–114. NIH/PMC Full Text
- Raffi, A., et al. (2012). "Behavioral and environmental correlates of coprophagia in pet dogs." Applied Animal Behaviour Science.
- Merck Veterinary Manual — Polyphagia and Pica in Dogs. Merck Veterinary Manual
- American Veterinary Society of Animal Behavior — Position Statement on Punishment. AVSAB
Tom Renshaw
All our authors care for dogs every day — read more of their work on the authors page.
