Why Tiny Dogs Lift Their Legs So High While Peeing

If you’ve ever crossed paths with a chihuahua, you’ll know that some of the tiniest dogs bark the biggest game. They often growl at and chase after dogs double their size, and according to a new theory, they may aim higher while peeing to make themselves seem mightier than they look.

Smaller dogs do tend to lift their legs at a higher angle to achieve a greater “pee height,” animal behavior researcher Julie Hecht writes for Scientific American. These findings, published in the Journal of Zoology, come from Betty McGuire, a dog researcher who is something of an expert on canine whizzing. McGuire, of Cornell University, studies dog urinary behavior, particularly as it relates to social and scent-marking habits.

Dog urine holds key information about the dog that left its mark, allowing dogs to communicate with each other from a distance (although anyone who has ever tried to stop a dog from sniffing every telephone pole they pass probably knows that). But what researchers didn’t know was whether dog pee height corresponded with the size of the dog.

“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.”

For this study, McGuire and her colleagues took 50 healthy adult shelter dogs (neutered and "intact," if you must know) of different breeds out on walks and recorded them peeing—for science, of course. Researchers then used the video footage to determine the angle of a dog’s raised leg as well as the height of the urine mark. When compared to information about a dog’s height and mass, they learned that pee height does accurately reflect a dog’s size in some cases—just not when it comes to smaller dogs.

McGuire told Scientific American that smaller dogs tend to “cheat” by raising their leg higher to achieve a higher trajectory. This may be because they want to seem larger in order to avoid conflicts with more imposing dogs. Another theory posits that smaller dogs might be trying to “over mark,” or cover up another dog’s pee—a behavior that’s common in mammals.

For more conclusive results, we'll just have to wait for the next doggy urine study to leak.