You are probably not prone to chowing down on poop, but some of our best friends beg to differ. While all dogs are not into the fresh stuff, some are decidedly inclined (heck, drawn) to gobble it up.
If you are still reading despite topic and tone, maybe it's personal. If one of your canine friends eats poop, you may wonder, "Why, dog? Why are you into this? And is it normal? And, well, could you maybe do it less?"
Here's what we know: dogs eat poop. They'll eat their own and that of other dogs. Other species' goods are also fair game—dinner time in the cat litter box anyone? How about an on-farm horse-candy snack? The scientific term for this phenomenon is called coprophagy, which is defined as "the eating of feces that is normal behavior among many animals" which sure sounds like what's going on with dogs. After all, early in life, mother dogs (dams) will "clean up" puppy's #2.
Who and why?
A new study published open access in the journal of Veterinary Medicine and Science by veterinary behaviorist Benjamin Hart and colleagues at University of California-Davis, School of Veterinary Medicine, used two online surveys to dig into the topic. The first survey, Dog Behavior: The Rest of the Story, covered both dogs who do and don't eat feces, while the second, Why Dogs Eat Their Stools, focused solely on eaters. Just over 3,000 dog owners participated, with the majority from the US followed by Canada. While owners noted that dogs also ate other species' feces—cat (obviously), cow, horse, wild bird, pig, sheep, goat, and that of other domestic animals—the study focused exclusively on dog consumption of dog feces.
As you know, some dogs eat dog poop, but it isn't for everyone. Sixteen percent of owners reported seeing their dog eat poop more than 6 times—the survey's criteria to be defined as a poop eater. This also means that in a general survey of dogs, many had never or were rarely observed ingesting the stuff. While it could be that owners of coprophagic dogs don't do surveys (they're out patrolling for poop. Kidding, kidding), the second survey—focusing exclusively on the topic at hand—pulled in almost 1500 responses, with 62% of these dogs described as eating it daily and 38% weekly. Wow.
But here's the thing: eaters weren't vastly different from non-eaters. In Hart and colleagues' survey, some young dogs ate stool, some didn't, some old did, and some didn't. Coprophagy wasn't associated with dog age, sex, neuter status, age of separation from the mother, ease of house training, or numerous owner-described problem behaviors.
Eaters and non-eaters also didn't differ in diet, which is notable as diet can be linked to coprophagy. It's also possible survey questions alone wouldn't pick up the nuances needed to explore a relationship between diet and coprophagy. And while Hart and colleagues' study didn't identify a relationship between coprophagy and compulsive or anxiety behaviors, an earlier 2010 study by Broox Boze in the Journal of Applied Companion Animal Behavior did. Also in that study, neutered males were more likely to eat poop than intact males, a finding that didn't appear in Hart and colleagues' survey. Maybe these differences can be attributed to differences between the two studies, such as the studies using different definitions of what constitutes a coprophagic dog. But the bigger point is: if it's feeling a bit murky about who eats poop, it's probably because it is murky. Looking at a dog, even with the above information, it would be difficult to correctly guess whether he or she eats poop.
But there might be a few indicators. A few differences between eaters and non-eaters emerged. Eaters were more likely to be found in multi-dog households, possibly because there's more to go around or maybe poop eating has a social, even learned, component. In the book The Dog: Its Behavior, Nutrition, & Health, Linda Case wonders whether, as social beings, a dog might notice another dog getting intimate with feces, be drawn to investigate, and behave similarly. For some dogs, boredom could play a role in the development or maintenance of the behavior. And given the zest with which some gobble it down, you have to wonder whether poop-eating taps into other senses, like odor and taste.
Coprophagic dogs were also more likely to be described as "greedy eaters" who "wolf down food" as opposed to "normal" or "finicky" eaters. And 85% were keen on the fresh stuff, preferring stool not more than two days old. Interest in the new stuff is what led Hart and colleagues to suggest this could be an adaptive behavior inherited from their wild ancestor to rid the environment of feces prior to parasite infections being able to spread, although they acknowledge more field observations of wolves and other canids are needed. Or, maybe dogs picked up this behavior as they scavenged for food sources in human environments. Just because you and I don't see the nutritional value in feces doesn't mean it isn't there.
If you're barely holding on or feeling queasy, I apologize for what's to come, but it brings us closer to why you may be sticking around. It appears owners are Poop Detectives. In the survey, owners claimed to know a dog had eaten "it" because "it" was there when they left, and gone when they returned. Excellent police work, human. But beyond that, most knew a dog had eaten stool because of the "tell-tale breath odor." The researchers leave it at that—and I wouldn't want them to expand—but I imagine this could be difficult for dog lovers to stomach. You bring a dog into your home to be a beloved family member, and then he or she brings that into your face.
Can it be stopped?
Here's the thing: poop eating is generally a normal dog behavior, and attempts to abolish it don't seem to work. Hart and colleagues had owners report on the effectiveness of 11 commercial products, and despite hard hitting names like Coproban, For-Bid, Dis-Taste, Deter, and yes, Potty Mouth, the "reported success rate for food additives or tablets marketed for coprophagy ranged from 0 to 2%." Owners overwhelmingly reported the products "did not help." Owners also shared their experiences with behavior modification and management solutions which also didn't bring the behavior to zero. Although, based on what we know about the science of behavior change, attempting to reward the dog for "leaving it alone" can't hurt.
Scoop the poop. Making it unavailable—for your dog and other dogs—is really the surest way to decrease the behavior because the poop becomes a ghost. It does not exist. But where there is a will, there is a way, and dog owners who pick up all or most stools claimed it still didn't stop poop eating entirely.
I'm reminded by veterinarians that poop eating is not always smooth sailing. Outcomes range from no trouble at all to more mild issues, like diarrhea, to the spread of different diseases, depending on what was consumed. Veterinary behaviorists Debra Horwitz and Gary Landsberg highlight that although coprophagia could simply be a dog into eating poop, the behavior could have medical underpinnings, and a veterinarian should be consulted if there's concern.
And now you. Well, not you, your dog. What's your dog's take on poop?
Boze, B. G. V. (2010). Correlated of coprophagy in the domestic dog (Canis familiaris) as assessed by owner report. Journal of Applied Companion Animal Behavior, 4(1), 28-38.
Hart, B. L., Hart, L.A., Thigpen, A. P., Tran, A. & Bain, M. J. (2018). The paradox of canine conspecific coprophagy. Veterinary Medicine and Science, Open Access.