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

Much as I hate to admit it in public, my beagle is a crotch hound. Is he really a pervert as my friends claim, or is something else going on here?

Something else is going on here and it’s called normal dog behavior, although admittedly it may appear more pronounced in scent hounds, such as beagles, bred for a particularly keen sense of smell. Unlike humans who depend primarily on vision for information about any new additions to our environments, dogs use their sense of smell to accomplish this same task. A scent-based system suits the dog’s lifestyle for two very good reasons. First, dogs possess only limited color and detail vision because they rely far more on their eyes to detect motion when hunting their prey or avoiding predators. Two, because wild canids often do their hunting in limited light, using a scent-based system that doesn’t depend on the presence of light to function works much better for them.

To understand how dogs determine each other’s identities using scent, recall how animals mark their territories using stool and urine. Additionally, when two strange animals initially meet, they circle each other in an attempt to sniff each other’s rear ends. The focus of their attention is a collection of glands around the anus and on the base of the tail that secrete very potent substances called pheromones. Among many mammals, pheromones communicate everything a top-notch photo does to us—and more. Not only do even trace amounts of pheromones inform other animals of an individual’s species and sex, these also advise them regarding that animal’s reproductive and social status.

Imagine finding a picture of a unknown person of the opposite sex lying on the sidewalk in front of your home. Chances are nothing in that picture would tell you whether the scarf you found a block away belonged to that person, let alone if that person were a) single and b) wanted to mate with you. However, the ability to collect and process all that data and more in a few whiffs serves as a tremendous energy-saving advantage to wild animals. Those who encounter the stool and urine of other animals on their own turf can determine whether this belongs to a potential friend or foe before they even meet. When they come face to face with a totally unknown animal, the other’s scent will determine how they respond to it. The resident animal may drive off an interloper of the same species and sex or it may defer to it, depending on the other animal’s social status. Females normally intolerant of the presence of males may welcome them in the breeding season and vice versa: males who shun female companionship in favor of that with other males may become ardent pursuers of females and attack those same males when they pick up the scent of a female in heat.

Because wild canids depend so heavily on scent to establish and protect their territories, find food and water, and locate receptive mates, it comes as no surprise that scent marking and processing comprises a deeply embedded part of the canine physiological and behavioral repertoire. However, even though we can say that our dogs’ ancestors literally survived by a nose, that same skill may actually undermine the dog’s survival in a human-canine environment. When Zippy zeroes in on Aunt Harriet’s crotch the first time she visits, he views this strictly as a fact-finding mission. He needs this data so he can position her in his world and then either deal with her, if he sees her as a threat, or move on to other pursuits (such as exploring her luggage). What Aunt Harriet and Zippy’s owner view as a disgusting display is the canine equivalent of Aunt Harriet’s young niece and nephew peering curiously at her as they conduct their own, vision-based fact-finding mission.

Although understanding why the behavior occurs should lead us to respond to it more tolerantly, the fact remains that few people enjoy being goosed by a dog, no matter how legitimate its reasons. Because of this, it makes sense to teach your pet to sit or lie quietly whenever anyone enters your home. If Zippy’s owners and all their friends and relatives ignore him when they enter, pretty soon he’ll get so bored with trying to sniff or leap on constantly moving targets who pay no attention to him, he’ll give up and settle down. Once he does that, his owners and guests can squat down and offer him a hand to sniff and pet him. Human hands may not carry all the news flashes available from crotches, but they usually supply enough information to satisfy most dogs’ desire for data as well as their owners’ need for decorum.