Photo: Mike Finkelstein (Flickr)

You just can’t trust a little dog.

We all know dogs can communicate through scent. They urinate on new areas, their own home turf, and certainly things that other dogs have peed on. We also know that some male dogs lift their legs in order to pee higher. But new research found that smaller dogs lift their legs at an even higher angle than larger dogs, perhaps to make themselves appear larger.

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“Our findings... provide additional evidence that scent marking can be dishonest,” the authors said in the study published recently in the Journal of Zoology.

The researchers from Cornell University first had to establish that the angle a dog raised its leg is a good stand-in for how high the pee goes. They took a bunch of shelter dogs for walks and filmed them peeing with an iPhone, and in some cases, a high-speed camera. And yes, based on their analysis, how high the dog raised its leg could predict how high the pee would go—as could the dog’s mass and height.

Here is Patches peeing:

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Then, they analyzed how a dog’s size compared to how much it lifted its leg. Both lighter and shorter dogs lifted their legs to higher angles than larger dogs. The little dogs seemed to be trying to leave a pee signature of a larger dog. From the study:

Thus, even though height of urine mark does reflect size of signaler in part, small dogs seem to “cheat” by using larger raised-leg angles to deposit higher urine marks, thereby exaggerating their size

The researchers write that it could be beneficial for dogs to “exaggerate their body size and competitive abilities” to avoid conflict with other dogs. The study also adds to a growing body of research supporting that smaller dogs and larger dogs behave differently.

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The researchers point out that the study has its limits and other possible interpretations. Maybe big dogs just can’t lift their legs as high as small dogs can, for example. And it would be up to future research to determine how dogs react to different scent mark heights. But they do point out that others have seen examples of “dishonest signaling” in other species, like the dwarf mongoose, in which scent marks appear in unexpected places given the animal’s size.

So next time you see a little dog pee, ask him: What are you trying to prove?

[Journal of Zoology via New Scientist]

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