Originally Posted by DogStarDaily

Olfactory Communication
Many dog owners have realized, dogs urinate far more frequently than is required by physiological need. Indeed, urinary scent marking serves many important functions, including territorial demarcation, sexual attraction, individual recognition and advertisement of puppy license.
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Territorial Marking?
The concept of territoriality incorporates the notions of marking as well as defence. In wolf packs, a greater concentration of male urine marks appear to be distributed along the peripheral buffer zone of the pack's territory compared with the core of the territory.

Perimeter marking by males is similarly prominent with domestic dogs. But, since most domestic dogs are confined to artificial “territories” by walls and fences, and since male dogs tend to urinate against vertical objects, one would expect the majority of urine marking to occur along the perimeter. Surprisingly though, perimeter marking was not observed in an observational study of free-ranging suburban domestic dogs, i.e., dogs which silly owners allowed to roam the neighborhood at different times of the day and night. Instead, free-roaming dogs regularly and heavily marked a number of often-used radial routes, which lead away from and back to their individual homes. Thus, most marking occurred close to home.

Free-roaming dogs did not actively protect the central area of their home range from other free-roaming dogs, nor did urinary scent marking appear to be effective in repelling other dogs, which freely entered and marked inhabited areas, sometimes when the resident was present. Free roaming domestic dogs do not appear to be in the least bit territorial and in fact, some dogs welcome visitors.

Dogs can distinguished between urine marks from different individuals and male dogs sniff and urinate more frequently in response to urine marks from unfamiliar males, compared with urine from familiar males and compared with their own urine. Also, a dog’s response to unfamiliar urine decreases with repeated exposure, as if “strange-male” urine progressively loses its strangeness. Rather than being an agonistic display of territorial defense, urinary scent marking by domestic dogs appears to be a means to make a strange environment smell like home, by masking the unfamiliar odors with individual urine. Urine marking appears to be the canine equivalent of personalizing a new home with furnishings and possessions.

Urinary scent marking is not the prerogative of male dogs. On the contrary, many bitches urine mark and also, many bitches will raise a leg when doing so. However, the female manner of raising a hind leg usually differs from the characteristic male leg lift posture. Male dogs stand with body weight forwards while a hind leg is abducted at the hip joint and the stifle swings out and upwards to lie above the backbone, so that urine may be jetted laterally towards some vertical object, which was in dire need of marking. Bitches, on the other hand, normally raise a hind paw which is brought forwards underneath the body, usually while the bitch is partially squatting. Often her rear end may be swiveled to one side to direct the urine.

Basically, dog urine is the canine equivalent of e-mail. P-mail if you like. Each urine mark contains its own message displayed on a communal message board. “Spot was here!” “So was Rex!” “Me too! Little Twerpie here.” “Hi! My name’s Butch and I’m ten months old.” “Well, my name’s Roger and I’ve been neutered.” “Shame! This is Trixie and I’m just hot to trot!” “Spot was here!” “Me too!” “Me too!” “Me too!” “And me. It’s Twerpie again!”