Kleine hondjes liegen vaker over hun grootte. Dat blijkt uit een net gepubliceerd onderzoek naar de hoogte van het markeerpunt. In normaal Nederlands: kleine hondjes plassen hoger dan hun lichaamslengte om zo groter te lijken, grote honden doen dat veel minder vaak.
Small dogs are more likely to lie about their size. This is shown by a recently published survey of the height of the marker. In normal English: small dogs urinate higher than their body height to look bigger, big dogs do that much less often. Small dogs also urinate more often than large dogs. According to the researchers, it is quite possible that small (er) dogs try to avoid direct confrontations with their larger counterparts, with potentially negative consequences. After all, in a fight a smaller dog will often lose it for a bigger one.
In mammals, urination is a well-known way of communication. It can be both territorial behavior "here I live" as a kind of contact ad in the direction of bitches in the neighborhood. A kind of "single man with good job seeks woman to care for posterity". The researchers, led by Betty McGuire, wanted to know to what extent these scent traces were now fair. Is a urine mark indeed a fair representation of the 'writer', of the urinating dog.
"Yes" the researchers say what about the smell. After all, a dog can not deliberately change it. The smell of the urine indicates exactly what kind of dog it is. From earlier experiments it is known that a dog recognizes itself by the smell of urine (the Yellow Snow study). Other studies also indicate that even in human urine dogs can indicate whether someone has prostate cancer, and other forms of cancer. What a dog exactly smells in urine, and what image it evokes in him (or her) is not known. From recent research we know that dogs can form an image based on and smell. So we can cautiously determine that a dog on the basis of the smell knows a bit about how the 'writer' of this pee message is living, whether he is healthy, or it is prepared ... etc.
"No" the researchers say on the basis of where the tree or pole is marked. Dogs lie about their size. And especially small dogs do that. The research first looked at whether the angle that the lifted hind leg makes with the body is a measure of the height of the dog with the same "angle" (most around 115˚). That turned out to be true. Then it was checked whether there was a connection between the height of the dog (withers) and that same angle. This showed that small dogs more often lifted their legs higher, in order to pee higher on the tree. And with that to other dogs that they were a lot bigger than they actually are. "It may be uniquely beneficial for small dogs to communicate indirectly (McGuire & Bemis, 2017) and exaggerate their body size and competitive abilities through relatively high scent marks if this allows them to avoid direct conflict. In contrast, large dogs have less incentive to avoid direct conflict due to their greater competitive abilities. "
There may also be other reasons for this high-marking behavior of small dogs. The "overmarking" (passing over an existing puddle) requires for small dogs to aim higher than for large dogs. Another possible explanation is that large dogs are physically less able to aim higher than a certain height, because of their construction they would fall over / out of balance more easily if they lifted their hind leg too high.
In summary, according to the researchers, dogs can lie with their urine. To what extent this is actually used in this way, needs further investigation.
The research was recently published in the Journal of Zoology.
Picture: Screenshots from a video of Patches, who was observed in Study 1. Horizontal lines compare height of urine mark and height of raised-leg. (a) Patches first held his raised leg at 115 degrees, resulting in a urine mark at 15.3 cm. We approximated height of urine mark by calculation. (b) At a later time during the same urination, Patches shifted his raised leg to 120 degrees, resulting in a urine mark at 17.8 cm. We measured height of urine mark from the base of the tree to the highest point of this second mark.