(Originally written for DogWatch, a newsletter for the general public from the Cornell University College of Veterinary Medicine)

My dog urinates in numerous locations in my house, which I’ve been told is territorial marking. The only place she’s never gone is in my bed. On the other hand, my cousin’s dog only urinates in his bed and he was told that’s territorial marking, too. How can these two opposite behaviors mean the same thing?

To understand the variations that may occur in marking behavior, we first need to understand territorial behavior itself. Recall that establishing and protecting the territory serves as the primary animal priority. The wild dog pack’s territorial nature leads its members to claim an area large enough to support them and any offspring, but not one so large that it requires excessive energy to adequately defend it. Within that space, the animals also protect certain prime locations—such as choice feeding sites and dens—more diligently than areas at the periphery.

However, because the ultimate goal remains to find food and water and reproduce, it makes sense to leave a token marker—such as scent-laden urine that communicates the resident’s willingness to protect this space if necessary—rather than actually physically challenging every suspicious interloper who approaches that space. Moreover, because marking itself requires energy, it also makes sense only to mark as much as is necessary to get the job done. Because animals communicate their sex and status in the pheromones in their urine, that typically means that the most vigorous animals in the pack do most of the marking because they pose the most threat to any interloper. (Imagine seeing a warning posted by the local police versus one posted by the third grade garden club: Which one would you take more seriously?) Thus, marking serves as a marvelously efficient way to avoid confrontations.

While a certain energy-efficient elegance underlies territorial theory when applied to a pack of wild animals, an individual pet’s personality, the quality of its environment, and its relationship with its owner may throw numerous curves into the process. Pet dogs living in complex human environments may find themselves trying to reach some sort of a workable compromise between the ancient drive to establish and protect a territory, and their own temperaments and any physical or other limitations that would make doing this a threatening endeavor. Under these circumstances, pets typically mark either that space they feel comfortable protecting or that which carries such a positive charge they’d risk injury or even death to protect it. In general, the less confident the dog and the more complex the environment, the more likely marking will occur, the more frequently it will occur, and the more it will involve intimate objects.

For example, Josie, a well-trained stable dog who lives on a quiet, dead-end street feels no need to make any territorial statements beyond the messages communicated in her daily eliminations. Sandy, who lacks Josie’s confidence plus lives in a busy suburb, lifts his leg on prominent fence posts and trees around the perimeter of his owner’s yard in an effort to scare off invaders. More timid Bumpus marks by the front and back doors, his way of saying he only claims (and thus only feels obligated to protect) what’s inside the house. Tuffy marks the upstairs hallway, effectively announcing his desire to protect all of his beloved owners’ sleeping quarters. Little Sugar only marks her owner’s belongings, and all of these except the bed; her litter mate, Spice, only marks her owner’s bed.

Additionally some pets will mark any new objects added to their territories, thereby claiming them and thus ruling out the need for a confrontation. Again, more confident animals may pee on the tires of the visitor’s vehicle, whereas those who feel more vulnerable may pee on the visitor’s belongings, or even the visitor himself.

In the majority of these cases, though, the marking exists because, due to a lack of training and other human displays that communicate leadership, owners have deliberately or unwittingly thrust this protective role upon their pets. Unfortunately, owners who don’t understand what the animal communicates via the display—i.e., its fear and willingness to fight to protect this sacred space—often view the pet as spiteful, mean, or stupid for ruining their belongings. While attributing such negative emotions to perfectly logical canine behaviors always ranks as a tragedy, it’s particularly sad in the case of very young, timid, or geriatric animals who believe they must protect their owners from the meter reader, school bus, and letter carrier day after day and endure the owner’s wrath, too. On the other hand, once caring owners understand what causes the behavior, they can relieve their pets of the territorial stresses that cause the problem.

So even though it looks like pee in the wrong place to us, it’s a goldmine of information about canine mental health.