Why do Dogs Eat Poop?

Laurie Anne Walden, DVM

Revolting as it seems to us, some dogs like to eat feces. If you’ve been the not-so-proud owner of a poop-eating dog, you’ve probably wondered why dogs have such a nasty habit and what you can do to stop it. Unfortunately, the short answers are (1) because they’re dogs and (2) not much.
 
Mother dogs ingest their puppies’ feces during cleaning, but that’s not the only time dogs eat stool. The scientific word for eating feces is coprophagy, and some dogs seem particularly enthusiastic about it.
 
Coprophagy in dogs hasn’t been extensively studied, but researchers from the University of California, Davis, School of Veterinary Medicine recently published the results of a new investigation of canine coprophagy.[1] They focused only on dogs that eat dog feces (not the feces of other species, like cats or horses). The investigators conducted 2 online surveys of dog owners and received over 3000 responses.
 
According to their results, 16% to 23% of dogs engage in coprophagy (depending on how strictly coprophagy is defined—that is, how many times a dog has to eat poop to be classified as a poop eater). Most coprophagic dogs in the study preferred fresh stool no more than 2 days old. Age, sex, neuter/spay status, and diet were not associated with coprophagy. Dogs that were hard to housetrain (and therefore might not mind being in close contact with feces) were no more likely to eat feces than were dogs easy to housetrain. Compulsive or anxious behavior was also not related to stool eating. These results may not be definitive, though; in a study published in 2010, anxiety disorders and neutering (in male dogs) were both associated with coprophagy.[2]
 
The researchers did turn up a few other factors linked to poop eating. Coprophagic dogs were more likely than noncoprophagic dogs to be described as “greedy eaters.” Terriers and hounds were more likely than other breed groups to be stool eaters (although in the 2010 study, sporting dogs had this dubious honor). The data did not allow for extensive analysis of specific breeds, but among the breeds that could be studied, the percentage of stool eaters was highest in Shetland sheepdogs and lowest in toy, miniature, and standard poodles. Not surprisingly, dogs in multiple-dog households (with access to more stool sources) and dogs reported to eat cat poop or dirt were more likely than others to eat dog feces.
 
The investigators asked survey participants about methods they used to (try to) control their dogs’ coprophagy. Reported methods ranged from behavior modification/management techniques (the most common of which was chasing the dog away from the poop) to various food additives. The success rates of all of these methods were abysmal. The highest success rate, only 4%, was with a reward-based “leave it alone” command. Everything else had success rates ranging from 0% to 2%. The authors were careful to point out that their data came from self-reported dog owner surveys. Clinical trials, if someone were to conduct them, might yield different results.
 
So is poop eating really a problem for dogs? It depends. A healthy dog who eats the stool of another healthy dog probably won’t have much trouble, although some types of fecal bacteria are hazardous if ingested. Parasite transmission is likely the biggest risk. Many intestinal parasites (like hookworms and roundworms) are spread through fecal-oral contact. And a couple of case reports have described dogs that developed drug toxicosis from eating the stools of housemate dogs that were taking medications.[3,4] A veterinary examination is always a good idea for a dog who eats stool, especially if the behavior is new or increasing, in case the dog has a medical reason for coprophagy.
 
If your dog eats stool, the best way to control it is to limit his access to feces. Picking up stool in the yard is just about the only way to keep a dog from eating it. Before you get angry at your dog or try punishment (which doesn’t work anyway), remember that this behavior is normal for dogs. The UC Davis researchers hypothesized that domestic dogs inherited the coprophagy habit from their wolf ancestors—so if nothing else, your poop-eating canine has lots of company.
 
References
1. Hart BL, Hart LA, Thigpen AP, Tran A, Bain MJ. The paradox of canine conspecific coprophagy. Vet Med Sci. 2018;4(2):106-114.
2. Boze BGV. Correlates of coprophagy in the domestic dog (Canis familiaris) as assessed by owner reports. J Appl Companion Anim Behav. 2010;4(1):28-37.
3. Hutchins RG, Messenger KM, Vaden SL. Suspected carprofen toxicosis caused by coprophagia in a dog. J Am Vet Med Assoc. 2013;243(5):709-711.
4. Shadwick SR, Ridgway MD, Kubier A. Thyrotoxicosis in a dog induced by the consumption of feces from a levothyroxine-supplemented housemate. Can Vet J. 2013;54(10):987-989.
 
Photo by Noel Lopez on Unsplash

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