Why Dogs Hump: We Don’t Know Why and Fast Answers Don’t Work

Scone mounting and humping Ruby from the front.

Source: Courtesy of Marc Bekoff

During the past two months, I've received numerous emails asking questions that center on why dogs mount and hump.¹ The simple answer is that there isn't any single answer to these very interesting questions. Unfortunately, myths about why they occur still prevail. Mounting and humping by dogs are among those behavior patterns about which humans make lots of assumptions when we really don't know much about them. Many people use the terms mounting and humping interchangeably, but sometimes a dog will mount another dog or someone’s leg and not thrust their hips. Dogs will mount and hump other dogs 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. Mounting and humping are dog-appropriate behaviors that many people find offensive.

I say we don't know why dogs mount and hump when they do it because there isn’t a single reason that applies across the board. Males and females do them to individuals of the same and opposite sex. Of course, male dogs do them to mate, but they also do them in other situations. In these cases, to understand why, it’s important to consider context, including who’s the initiator and who’s the recipient, the nature of their social relationship, and when and where it’s happening.

Humping can be an expression of interest in mating, dominance, or play, or a dog may just wind up in that position and some reflex gets triggered. What about dominance and mounting? In an article on mounting, Peter Borchelt, a certified applied animal behaviorist (CAAB), 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 often wonder if, on occasion, some dogs hump simply because they can. When this happens, be a citizen scientist and take note of what happens before and after mounting and humping. This can tell you more about the behaviors themselves and also can help you determine when they need to be managed and when it’s just fine.

Mounting, with or without humping, could also be what ethologists call a displacement behavior, meaning that it’s a by-product of conflicted emotions.² For example, dogs often mount and hump 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. For some dogs, a new visitor to the house could elicit a mixture of excitement and stress that could trigger a dog to engage in mounting and possibly humping. Or, just like we might flip on the TV when we’re bored, some dogs might develop the habit of mounting and humping during downtime or when getting better acquainted with a pillow.

Mounting and humping also are also very common during play, sometimes as an attention-getter, affiliative behavior, or when a dog is overexcited. I’ve seen dogs going “berserk,” enjoying their zoomies, running here and there, and mounting and humping a friend and then a ball with reckless abandon. A few years ago, at a local dog park, a man told me an interesting story about his dog Reggie:

“My dog Reggie, a male, is a humper—anything and anyone — water bowl, beach ball, other dogs from different orientations, and human legs. I can’t say why and surely I can’t provide an overall explanation. He just likes to do it, and if another dog or a human rejects him, he sort of shrugs and tries again with someone else. I don’t allow him to do it to me, and I say no, but that doesn’t work in other situations. When he’s rejected, he just slides off and goes elsewhere.”

It's high time to stop spreading myths about mounting and humping

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.

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

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The bigger question is, “What do mounting and humping mean to your dog?” To answer this question, consider them in the context in which one or the other or both occur. For example, what happens before mounting, and how often and for how long does it occur? If mounting suggests a dog is understimulated, perhaps it 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 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.

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 and humping into one fast universal explanation. So, what’s your dog’s behavior telling you? Perhaps your dog mounts and humps only occasionally because they like to do it, and you can leave it at that.

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 let them be dogs. One thing's for sure: dogs hump because they can and often enjoy doing it.