Why Dogs Hump

"On a beautiful, warm afternoon, I watched a group of dogs frolic in a dog park. Suddenly, I heard a woman’s high-pitched yelp, followed by the pounding of human feet. There was no need to look; it was obviously about humping, which we can also refer to as mounting." So wrote Julie Hecht in her excellent review of humping by dogs.

Mounting and humping by dogs are among those behavior patterns about which humans make lots of assumptions but we really don't know much about them. Dogs will mount and hump other dogs and other nonhuman animals (animals) from a wide variety of positions, human legs, and objects such as beach balls, water buckets, food bowls, pillows, and garbage pails without a care in the world. If you want to watch please do but an audience isn't necessary. Sometimes they hold on for upwards of 20-30 seconds and sometimes they just jump on and slide off and saunter away. And size doesn't matter.

While many humans feel embarrassed when they see a beloved four-legged friend mount and hump in public places, this behavior is a normal part of a dog’s behavioral repertoire. Both males and females mount and hump, and these behaviors first appear early in a dog’s life, particularly during play. Mounting and humping should not be considered abnormal behavior patterns.

While mounting is best known for its role in reproduction, it also occurs in many other contexts and emotional states. Dogs mount when they're excited and aroused and even when they're stressed and anxious. Take out the leash to go for a walk and Lassie starts humping Toto. You come home after a long day’s work and Spot goes for your leg.

Mounting could also be what ethologists call a displacement behavior, meaning that it's a byproduct of conflicted emotions. For some dogs, a new visitor to the house could elicit a mixture of excitement and stress that could make for a humping dog. And as we might flip on the TV when we’re bored, some dogs develop the habit of mounting during downtime, getting better acquainted with a pillow. Mounting is also very common during play, sometimes as an attention-getter, an affiliative behavior, or when a dog is over-excited. I've seen dogs going "berserk," enjoying that "doggy fit"—running here and there and mounting and humping a friend and then a ball. 

What about dominance and mounting? In a recent article on mounting, Peter Borchelt, a Certified Applied Animal Behaviorist (CAAB) in New York City, noted, “Mounting could be part of a suite of behaviors associated with aggression, such as high posture, resource guarding, direct stares, and threats and standing over. But mounting, in and of itself, doesn’t indicate a status issue. By itself, mounting might not mean a lot” (cited in Hecht, 2012). 

In my own studies of the development of social behavior in young dogs, coyotes, and wolves, mounting, clasping, and humping were not directly related to dominance, nor were they associated with dominance for the wild coyotes my students and I studied in the Grand Teton National Park outside of Jackson, Wyoming.

I wonder if in some situations, dogs mount and perhaps hump others when there are dogs around who can see them doing it. Years ago in a detailed study of urination patterns in dogs I could easily follow, I discovered they often engaged in what I called "dry marking;" they'd lift a leg but wouldn't urinate. When I looked at the social situations in which this happened, it turned out that dry marking occurred more when other dogs were around than when the dog was alone. I concluded that leg-lifting might be a visual signal in and of itself telling other individuals something like "I (the dog) just peed." It would be interesting to know if dogs mount and hump more when other dogs can see them, and if so, perhaps in some situations mounting and humping may have something to do with telling others about relative dominance.

Future research is also needed to determine how often mounting leads to humping. We really don't know all that much about these behavior patterns and how often they're linked together so generalizations about what they mean to the dogs involved need to be put on hold. 

Is humping a problem and what can you do about it?

Are mounting and humping problems about which we should be concerned? Mounting, including humping and masturbation, are normal behaviors according to the ASPCA (and others), although for some dogs, they could become a compulsive habit such as excessive tail-chasing.

The bigger question is, “What do mounting and humping mean to your dog?” To answer this question consider them in the context in one or the other or both occur. For example, what happens before mounting and how often and how long does it occur? If mounting suggests a dog is under-stimulated perhaps they could be provided with additional mental or physical activities. If mounting suggests anxiety it would be good to increase a dog’s comfort level in a particular situation, Or, if a dog gets overstimulated and goes bonkers or gets rude or impolite during social interactions with other dogs or people, it would be good to encourage mutually-beneficial interactions. Guardians (aka owners) can intervene in mounting and humping by getting the dog's attention-getting or by teaching an alternate behavior to assist the dog in their interactions with others.

Perhaps your dog mounts and/or humps only occasionally because they like to do it and can, and you can leave it at that. Let them be dogs.

Getting behind mounting and humping

Julie Hecht concludes her review of humping as follows: "When trying to get behind any behavior (pun intended), [Marc] Bekoff recommends becoming an at-home ethologist. 'Get a paper and pencil, and watch and record what happens before and after the behavior of interest. This can tell you more about the behavior itself.' This technique can help you determine when a behavior needs to be managed and when it’s just fine.

"If dogs could talk—and they actually are with their behavior—they’d ask us not to clump mounting into one universal meaning. So what’s your dog’s mounting behavior telling you?

"All in all, when we’re trying to figure out a behavior, we’re better served by observation and understanding of its roots than by the stories we tend to tell ourselves and others."

Clearly, there isn't a single explanation for mounting or humping. Mounting and humping are normal behavior patterns so let's not allow our own discomfort to get in the way of dogs doing what comes naturally. You can turn away, pretend it isn't happening, or giggle nervously and, as I wrote above, let them be dogs. One thing's for sure: dogs hump because they can.