Life with a dog is just full of surprises, some lovely and others simply confusing, at least at first. If your dog has a penchant for peeing over the same exact spot where another canine just peed, then he's participating in a classic doggie behavior known as "overmarking."
Dogs often cover up other dogs' urine as a means of expressing social power. If a dog feels tougher and more "alpha" than another individual he perceives to be meek and timid, he might communicate that by concealing the other furry guy's pee with his own. It might even be his way of marketing himself to the other nearby canines, or trying to hold on to the status quo, socially.
Overmarking Indoors and Outdoors
Overmarking can happen under numerous different circumstances. An elderly pooch might overmark the pee of a brand new puppy who is in the midst of the housebreaking process -- and all of the indoor potty soiling woes that frequently accompany it. A dog might closely trail another on outdoor walks in the park, only to promptly overtake the other pet's urine with his own. If a dog in your home has a territorial urine marking problem, it could influence another one of your cuties to do the same and start up with some urine marking of his own, overmarking style. Not fun.
Competition for Females
Overmarking in canines isn't always related to social status. Male dogs also sometimes overmark for a totally different reason -- to cover up the odor of female urine. If a male canine doesn't want fellow male canines to become aware of a female dog's presence, he might overwhelm her pee using his own. When it comes to female company, intact male dogs can be extremely ambitious creatures.
Genders and Overmarking
Canines of both genders are capable of overmarking, although the behavior is a little more prevalent in males, just as with standard urine marking. Never assume, however, that female dogs don't participate in this type of behavior.
Adjacent marking in dogs is a lot like overmarking, just with a subtle difference. When a dog pees right over another dog's pee, he's overmarking. If he does so nearby but not right over the pee, then he's adjacent marking. "Countermarking" is an umbrella term that describes overmarking and adjacent marking alike.