Take your dog for a walk and you might notice that there's some urinating involved. The tree. The lamp post. The fire hydrant. This scent marking is a way for your dog to communicate to other canine passers-by.
By sharing and sniffing, dogs are able to get information about sex, reproductive status and the identity of other four-footed visitors who have traveled the same path. Although female dogs do it too, this frequent marking is often done by male pups.
Typically the marking communicates true information about the marker; it's what researchers refer to as an "honest signal." When another dog comes along and takes a sniff, the info they get in the message is true.
But new data suggests that in some circumstances, dogs tell little white lies when they lift a leg. Researchers found that little dogs tend to hike high in order to give the impression that they're bigger than they really are.
Betty McGuire and her team at Cornell University studied this "dishonest signal." They noticed that smaller dogs tend to urinate more often than larger dogs, and they're more likely to aim higher when focusing on vertically oriented targets.
In their study published in the Journal of Zoology, they wrote, "Assuming body size is a proxy for competitive ability, small adult male dogs may place urine marks higher, relative to their own body size, than larger adult male dogs to exaggerate their competitive ability."
The researchers recorded adult male dogs while they urinated on walks, then calculated the angle of their legs when raised during marking. They compared those calculations to the dogs' height and mass and measured the height of the urine marks on the dogs' chosen targets.
"Small males seemed to make an extra effort to raise their leg high—some small males would almost topple over," McGuire tells New Scientist. "So, we wondered whether small males try to exaggerate their body size by leaving high urine marks."
As expected, when the dogs lifted a leg at a greater angle, they hit higher on a surface. But they found that small dogs angled the leg proportionately higher than larger dogs, resulting in marking higher than expected for their small stature. The researchers said it's likely the goal is to deceive other male dogs.
“Direct social interactions with other dogs may be particularly risky for small dogs,” says McGuire.
Because they can't measure up physically with larger dogs, smaller dogs can establish a virtually larger presence this way.
So they aim high to look big.