If you notice dogs aiming as high as possible when they pee in public, there might be a very good reason for that: they're trying to trick other dogs into thinking they're taller than they really are.
We already know that dogs leave a urine marker to label their territory or as a calling card to other canines, but a new study has now revealed the importance of height – the smaller a pooch is, the higher it seems to strain to shoot its spray of pee.
Researchers from Cornell University in New York filmed and analysed the peeing patterns of 45 male dogs as they went about their business in the local area. Smaller dogs peed more often, and chose vertical targets (like trees) more frequently.
"Small males seemed to make an extra effort to raise their leg high – some small males would almost topple over," one of the researchers, Betty McGuire, told Jake Buehler at New Scientist.
"So, we wondered whether small males try to exaggerate their body size by leaving high urine marks."
While the urine of male dogs is usually an honest odour-based message of that dog's health, sex, and age, it would seem the height it's sprayed at is maybe a little bit less honest.
Without knowing what the dogs are thinking, its impossible to be sure; but it makes sense that smaller pooches would want to exaggerate their stature to neighbouring dogs considering moving in on the same patch.
The increased frequency of the urination from the smaller dogs might be an attempt to avoid physical contact – like sending a text rather than meeting face-to-face, where they would be at a disadvantage – suggest the researchers.
In fact, many mammals try and leave their 'scent marks' as high as possible – likely because it makes them easier to see and separate from any other smells that might be on the ground.
So now we can add dogs to the list too. It does seem that the males of a variety of species are keen to get their urine markers as high off the ground as they can (female pooches, meanwhile, tend to squat while peeing).
A couple of other explanations have been put forward by the researchers: one is that smaller dogs are just more agile, and better able to lift their hind legs. In other words, all dogs are trying to pee as high as possible, it's just that small dogs are better at it.
Alternatively, the high-shooting dogs might be trying to cover up scent marks left by other neighbourhood canines, like painting over graffiti.
We'll need more research – and more walks around the block – to find out for sure. In the meantime, the team behind this latest study thinks the first hypothesis is the most likely.
"Small dogs seem to 'cheat' by using larger raised-leg angles to deposit higher urine marks, thereby exaggerating their size," conclude the researchers.
The research has been published in the Journal of Zoology.