Peemail: Dogs and People Writing Messages in Urine

Source: Gianni Crestani from Pixabay CC(0)

It is sometimes convenient to think of dogs reading scents as the equivalent of people of reading a written message. One of the ways that dogs communicate with each other using scents involves leaving splashes of urine, a sort of "peemail."

Many biologically relevant hormonal chemicals (known as pheromones) are found dissolved in a dog's urine. That means that a dog's urine contains a great deal of information about that dog. It smells differently depending upon the dog's age and health. It smells differently for males or females, and females in heat. It even smells differently depending upon the dog's emotional state.

This means that sniffing a fire hydrant or a tree along a route popular with other dogs is a means of keeping abreast of current events. That tree is really a large dog tabloid containing the latest news items in the dog world. While it may not contain installments of classic canine literature, it certainly will have a gossip column and the personals section of the classified ads.

When my dogs are busily sniffing at a favorite post or a tree on a city a street frequented by other dogs, I sometimes fantasize that I can hear them reading the news out loud. Perhaps this morning's edition goes "Gigi, a young female Miniature Poodle has just arrived in this neighbourhood and is looking for companionship — neutered males need not apply." or "Rosco, a strong middle-aged German Shepherd Dog, is announcing that he is top dog now, and is marking this whole city as his territory. He says that anybody who wishes to challenge this claim had better make sure that their medical insurance is current and paid up."

The reason that fire hydrants and trees are popular places for urinating is that male dogs prefer to "mark" vertical surfaces. Having the scent above the ground allows the air to carry it much further. Perhaps the most important reason for using elevated and vertical surfaces as the target for urine is that the height of the marking tells the neighborhood something about the size of the dog making the mark. Remember that among canines, size is an important factor in determining dominance. Since dominance seems to be more important to males, they have developed the habit of leg lifting when they urinate so that they can aim their urine higher. Also, the higher the marking, the more difficult it is for other dogs to mark over it and obscure the message. These peemail messages also provide an opportunity for dogs to tell lies about their size and social status.

Dogs and wolves often use urine to mark their territories. Roger Peters, a psychologist and wolf researcher, studied these markings. He found that the wolves use urine to mark the perimeter of their territory, so that, in effect, they live inside a region ringed in urine. They also use urine to mark certain pathways that are important to them. This means that, for the wolves, these urine scent posts form a sort of a map of their region, telling visitors about the inhabitants, and reassuring the members of the pack that they have returned to familiar terrain. Wolves and dogs will mark more frequently as they move out of their own territory, and it has been suggested that this has the same purpose as a human's blazing of trees, so that he can find his way back home after the journey.

Obviously, we as humans are relatively oblivious as to the actual content of the messages left by dogs in their urine. However, there have been some cases though, where humans have attempted to communicate something to dogs using urine. The Canadian naturalist and author, Farley Mowat, wanted to assure the safety and privacy of his campsite while observing wolves. He carefully urinated on rocks which marked a perimeter around his living area. When the wolves discovered his scent marks, they went around to the opposite side of each rock and marked it with their scent. Thus, each rock had a side announcing Mowat's territory and another marking the border of the wolves territory. Mowat reports that although the wolves would often patrol along that smelly boundary, they clearly did get the message and they respected his space.

I personally know of an instance where human scent markings were used to successfully communicate with domestic dogs. A friend and colleague of mine at the university had a problem. His wife had decided to put in some new flowerbeds on either side of the front door to his house. She dug up the earth and surrounded the beds with decorative rocks. Unfortunately, the newly turned soil and the smell of the new plants attracted some of the neighborhood dogs, who were digging out her flowers almost as quickly as she planted them.

My friend had read Mowat's wonderful book Never Cry Wolf and thought that perhaps he could mark the rocks surrounding the flowerbeds with urine (sort of defining a tiny botanical territory) and that might keep the dogs away. That night, he snuck out of the house and carefully urinated around one of the flowerbeds. He only marked around one, because, as a scientist, he wanted to test the effects experimentally and this allowed him to compare the results across the two beds.

Sure enough, over the next 48 hours, the unmarked flowerbeds were disturbed and partially dug up, while the urine marked beds were not. Flushed with success (and a full pot of tea — to provide fluid to make extra urine) he marked both beds this time. Since he knew that the effects would wear off in time, he renewed the marks every few days and the neighborhood dogs seemed to respond as he had hoped. They would sometimes come up and urinate on the rocks that made up the boundary, but they did not cross over and they did not dig.

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Success does not always come easily. A few weeks into his territory marking program, he gave me a phone call looking for another solution to his problem.

"It's working with the dogs, but it has resulted in other problems. I do it at night to be discreet, but this morning as I was leaving for work, my neighbor stopped me. 'I know what it's like having a house full of daughters who always seem to be in the bathroom when you need it. Since you seem to be encountering that problem a lot, you can just tap on my door if you need to use the toilet instead of... well, you know.'

"Even worse, when my wife found out what I was doing, she was disgusted by the whole thing. 'You don't expect me to work in those flowerbeds after you've just used the borders for a lavatory — do you?' So tell me, what am I supposed to do?"

I told him to take a little bit of household cleaner — one with some form of noticeable scent — and mix it with ammonia (which is one of the odorants in urine). The household cleaner was there just to give some complexity to the scent (and to convince his wife that the rock border hand now been cleaned) while the ammonia was to make it all smell like some form of strange urine. I told him to put it in a spray bottle and apply it to the rocks surrounding the flowerbeds. He did, and the flowers have still not been disturbed, although I often wonder about what kind of dog the neighborhood canines think that that scent represents.

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