Ever wonder why some dogs seem to savor eating feces—their own, and sometimes that of other dogs? It’s understandable how upsetting this habit would be to their humans, and a team of researchers from the Center for Companion Animal Health, University of California, Davis, tried to get to the bottom of this problem. (pun intended)
Their findings were presented in their study report, titled, “The paradox of canine conspecific coprophagy.” The word conspecific denotes animals from the same species; so, while some dogs are attracted to stools of other species like cows, horses or cats, they were not considered. This study only focused on those who favored the canine variety.
The researchers, led by the eminent professor emeritus Benjamin Hart, posited that coprophagy is a paradox because dogs “seem to find conspecific feces aversive and typically keep their ‘den’ areas clean by eliminating outside the house.” Meaning, dogs can be housetrained easily due feces aversion. It is also one of the reasons that some advocate crates when housetraining—dogs rarely defecate where they sleep.
So then, why do some dogs eat their poop? The researchers assure us that commonly held beliefs such as “a gastrointestinal upset, nutritional deficiency or compulsive disorder” had “no clinically established abnormality associated with the behavior.”
Not only do dogs eat poop, but some considered to be coprophagic typically eat it fresh. Through two extensive web-based surveys, the study found that 16% of the dogs sampled were observed eating fresh stool at least six times (this is the group determined to be coprophagic). Of this group, 76% were even more frequent poop nibblers, sampling it more than 10 times. The researchers found few similarities among this group: not age or their regular diet or the age at which they were weaned; plus, they were all reported to have been easily housetrained.
The dogs did have some things in common, however. They were described as “greedy” eaters (the range of eating styles included “finicky, greedy and normal”), lived in multi-dog households, and would also eat dirt and cat stools. Many were terriers or hounds.
The researchers had four objectives: first, to collect demographic information such as age, breed type, gender and neutering, number of dogs in household, type of food fed, eating behavioral patterns, and so forth. Another survey then directed additional questions to owners of coprophagic dogs, including the ease or difficulty in housetraining, the “age” of the stools that were consumed, and any behavioral modification procedures used to discourage it. Finally, since many products on the market purport to stop coprophagia, they asked about their use and effectiveness.
Surprisingly, coprophagy did not seem to be a “reflection of juvenile behavior”; 75% of the coprophagic dogs were more than four years old. Also, the habit did not seem “to be associated with compulsive-like behaviors.” Although the sample size was too small to make any firm conclusions based on breeds, the analysis did find that hounds and terriers were more likely coprophagic than other dogs.
Analyzing the feces-eating dogs found that behavioral management did little to alter this behavior, with the “leave it” command scoring the highest rate of 4% (which is still really low). But the use of food additives and pills marketed for coprophagia scored even more dismally, with only one of the 11 products scoring 2%; three others had a 1% rate, and the rest came in with zero. (They did note that their survey did not explore the degree to which the respondents closely followed directions on the label for those products.)
As to the why of it all, the researchers put forth two hypotheses: one, these dogs are “exhibiting an abnormal behavior stemming from one or more contributing causes,” but none of their findings supported any of those causes. The second, that coprophagy is an adaptive behavioral defense that comes from dogs’ wolf ancestors. It is thought that wolves would consume “fresh feces of injured or sick pack members that might be deposited in the rest areas near the den. If wolves were to remove the feces from rest areas where infective larvae from intestinal parasites would become more numerous over time, consumption is the only method available.”
Now, isn’t that interesting! So wolves ate the poop of pack members to help keep their dens parasite-free. (How wolves would know that poop contained unwelcomed parasites was not explained.) And while the researchers could not find any studies that detailed such behavior with wolves (or other canids), they added, “a comment by noted wolf authority L. David Mech that ‘wolves do commonly practice coprophagy, at least in captivity,’ offers support for this perspective, which was further reinforced by a personal communication with Mech.” If this analysis is correct, then poop-eating dogs might just might be showing off their wolfish roots, a more imaginative and less worrisome explanation than the other options.
The fact that the poop-eating dogs were also found to be “greedy” eaters also lends credence to a Canis lupus antecedent, as the paper noted, “because one would expect greedy eating to be a common wolf characteristic.” (Perhaps that’s why gulping down food was first characterized as “wolfing down” in the 1860s.)
The study ends by reconfirming that coprophagy is not really medically harmful to dogs, although, sadly, some of their humans might find it so disgusting “that the bond with their dog is irreparably damaged.” They also offer a few caveats about the poor showing of the poop-eating-deterrent products, because they cannot attest to how well treatment guidelines were followed. The same can be inferred about behavioral modification techniques, since the researchers did not know how reliably any one method was employed or followed up on.
Perhaps training a more reliable response to the “leave it” cue would help in these situations, as would using high-value treats to redirect attention and reduce foraging mishaps.