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Why Do Small Dogs Lift Their Legs Higher to Pee?

Image via iStock.com/Aleksei Andreev

By Kerri Fivecoat-Campbell

Barney, an 11-year-old Chihuahua, is a small dog who weighs in at 9 pounds, but when he pees, Barney lifts his leg as high as possible. But why? Put simply, he might want all the other dogs who pass by to think he’s much larger.

Chris Quaal Vinson, Barney’s dog mom, who lives with him in their rural Bowstring, Minnesota home, thinks her dog does just that. “Since we live in the north woods, we often have animal visitors around our property at night. Every morning, Barney has to sniff their scents and mark his territory once again,” says Vinson. “When he smells the others, that’s when he lifts his leg even higher.”

Setting Up Studies to Test Dog Marking Theories

A new study conducted by scientists at Cornell University found that Barney is not the only tiny pup who exhibits this strange dog peeing behavior. The study concluded that smaller dogs tend to lift their legs higher than larger dogs.

“It might be uniquely beneficial for small dogs to exaggerate their body size and competitive abilities through relatively high scent marks if this enables them to avoid direct conflict,” says Betty McGuire, a researcher in the study who has a PhD in ecology and evolutionary biology. “In contrast, large dogs, with greater competitive abilities, would have less incentive to avoid direct conflict.”

McGuire is a lifelong dog lover, and this wasn’t her first study regarding dog behavior and dog urine. While at Smith College in the early 2000s, she coauthored two studies on scent marking in dogs.  

In her most recent two studies, McGuire sought to learn how size affects scent marking in male dogs. She used shelter dogs, mostly mixed breeds of varying size, to assess if small dogs do indeed lift their leg at a higher angle and therefore pee higher, in comparison to large dogs.

Puppies weren’t used in the study because they typically still squat, and older dogs weren’t chosen for the study because they might have mobility issues. “We used only adult male dogs between 1-7 years old,” says McGuire.

McGuire would walk a dog, and a student would take a video of the walk. “If we were lucky, the dog hit a target taller than himself,” says McGuire, adding that was one of the conditions of the study. Once the dog peed, the conditions had to be favorable for ascertaining the mark line and measuring the height. Sometimes, this couldn’t be done if the object was already wet or other dog pee was present.

Other challenges involved the time they had with the shelter dogs. “We may have only been able to walk them once before they were adopted, or sometimes multiple times,” says McGuire.

Study Provides Insight on Dog Marking

“In our first study of scent marking and body size, we found that small dogs urinated more frequently than did large dogs and were more likely to direct their urine at targets in the environment,” says McGuire. “We also noticed during the course of our observations for that study that while adult males performed raised-leg urinations, small males seemed to make an extra effort to raise their leg high, so much so that some males would almost topple over.”

At the end of the study, researchers concluded that small dogs do, in fact, lift their legs at higher angles to mark a higher spot with dog pee. Based on previous research conducted over the years that showed that larger dogs have higher competitive abilities, McGuire and her colleagues concluded that small dogs may be trying to exaggerate their body size and competitive abilities through higher scent marks. In other words, a small dog might benefit from avoiding direct conflict more than a big dog.

Still, researchers can’t know for sure. “Another possible explanation for our findings is over-marking, the tendency for male dogs to place their urine on top of urine marks previously left by other dogs,” says McGuire. “Compared to large dogs, small dogs will encounter more marks that are higher in relation to their own body size for them to over-mark, and this could produce the pattern we observed.”

McGuire says that although we can’t know for sure why smaller dogs tend to lift their leg at higher angles while peeing, the study will hopefully give veterinarians and dog parents some insight about typical behavior. 

Their research also benefited the shelter dogs. During the two studies, 1,000 dogs were taken on 2,800 walks. “Importantly, our research also provides shelter dogs with additional opportunities for human interaction, exercise and display of species-typical behavior such as sniffing and urine marking,” says McGuire.

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