Why Do Dogs Hump?

I receive numerous emails asking something like, "Why does my dog hump other dogs?" Sometimes people ask, "Why does my dog hump his water bowl, her favorite toy, or my or other peoples' legs?" or "Why does my dog hump everything they can?" The simple and most honest answer is, "We really don't know." There's no general answer to this often-asked question, and it all depends on the individual dog and specific social context. But there's no shortage of discussions about why dogs hump, and so it's time to put various myths to sleep.

Yes, male dogs mount and hump females when they're trying to make more of themselves, but there's no evidence that humping is strongly—scientists would say "statistically significantly"—related to dominance, gender, age, specific breeds or mutts, specific social and other contexts outside of mating, or gender. My own observations suggest—and I emphasize suggest—that males do it slightly more than females, that there are dogs who hump considerably more than others, and that it happens in many different social and other contexts outside of courtship and mating. However, these are guesses rather than facts. And my observations suggest that while a dog might direct his or her humping to specific individuals or perform it during play when they're going berserk and simply wind up on top of another dog in one orientation or another, there aren't enough data to make this anything more than an educated guess. Further, while we might think that humping can be misdirected, as in the image below, this isn't necessarily so, because humping isn't only related to procreative inclinations. Sometimes it just happens.

Dog humping another dog.

Source: Shutterstock, free download

I'm always glad to hear from people who have questions about humping along with observations of "citizen scientists." I recently received a very interesting email from Dale McLelland, a dog trainer in the UK. She wrote:

"Could I ask you a question about humping please? I have been looking for resources but not quite the right info that I need. Male dog about 8 years old neutered, meets 2 male (n) dogs for the first time, is as expected with one but becomes fixated on the other, trying to hump but at a really aroused level (almost like a male meeting a female in season). Owner takes him away but he cries and paces and pants, trying to pull back towards the other dog. I have him here for boarding holidays and although he may on occasion try a wee hump he can be called away and actually doesn't show too much interest anyway. The owner of the dog that was being humped says that it happens a lot to the dog and he will eventually snap to ask them to stop. So my question is why do some dogs seem to be the object of humping at such an aroused level? I see dogs having wee humps at others and really is over fairly quickly but this situation appears to be one that this dog experiences often and at such an excited level. Do dogs mistake the smell of a neutered dog for that of a female? Is it to do with the lack of testosterone but why only some dogs? Is it to do with the willingness of the dog to accept the attention which allows the humping dog to get more and more aroused (rather than an objection early on that would stop it at the early stages). I have entire dogs for boarding holidays and it seems to be the neutered males that are more prone to humping."

These are interesting observations and questions for which there are no general or reliable answers. I answered:

"In all honesty, I have no idea how to explain these sorts of encounters. I've been keeping an informal list of situations in which males and females hump and I can't see any patterns at all. It seems like males do it more than females, but I've seen some females who are 'humpers.' And, because so many dogs here have been 'fixed,' I can't get any comparative information on fixed versus intact males or females. Your questions are great, but once again I just don't know. I've often thought that this would be a great undergraduate or graduate project and have someone collect data in a rigorous systematic way so that your questions and others could be answered with some reliability. For starters, they'd need information on age, gender, fixed or not, social context, individual personalities, size etc etc. I have no idea which would be important but a multivariable analysis would be very useful. So, sorry I can't say more, but let me think some more on this as it's such an important question and so many people ask me about it and want to know more."

Dale replied:

"I have two young Old English Sheepdogs and neither is fixed, the female will sometimes hump my leg if I am sitting down and she has just come back in from outside (she never humps a dog though), my male dog never humps anything (human or dog). It's a real puzzle and I am guessing that there won't be one answer, as with everything dog, it will be 'it depends' ha ha. As far as the males who come here for boarding are concerned, it seems to be the neutered males that do most humping or are on the receiving end. I have two spayed females that I can think of (a chocolate lab and a retriever) and they hump when excited--basically any dog that they are close to. The retriever will 'air hump' if other dogs are playing and the excitement levels increase, she follows them around humping away at nothing. Such an interesting topic and maybe one day someone will take it on for a research project."

I included the full text of our exchanges because they clearly show that there are a number of variables that need to be included in any discussion or study of why dogs hump, and it's clear we really don't know. The variables would need to include at least who the dog is—their personality and past experiences, age, gender, breed, mix, fixed or not, and social or another context. In Unleashing Your Dog: A Field Guide to Giving Your Canine Companion the Best Life Possible Jessica Pierce and I note that in human culture humping is a perverted, inappropriate sexual behavior, and not something to do in public. However, in dog culture humping is entirely dog-appropriate and does not need to be private. They'll hump all parts of other dogs, a human leg, a couch leg, a pillow, or whoever or whatever is around. And, as Dale puts it, they'll sometimes "air hump" in a frenzy.

It's obvious that we need some rigorous systematic research on the question, "Why dogs hump?" And, we also need to pay careful attention to individual dogs. Some are inveterate humpers, some do it from time-to-time but we don't know why, and some don't do it much if at all. In Canine Confidential: Why Dogs Do What They Do, I wrote about two dogs I called Harry and Helen, the "happy jumpers," who unhesitatingly would jump on other dogs, from all different orientations, some rather acrobatic, and hump away as if it were nothing. There was no consistency to why they did it, but they clearly enjoyed doing it as have other dogs I've observed. On more than one occasion, they chose one of my legs for their maniacal humping and thrusting. Helen’s human often exclaimed, "'Oh my god, my dog was fixed to stop this stuff.'" I've also heard people authoritatively state something like, "He’s gonna hump her because he really wants to mate with her, not play with her.” This of course isn't necessarily so. And I've heard people say maybe some dogs hump because they simply like to do it. Martha once said to me about her dog, Miranda, "She just loves to mount and hump and there isn't any pattern to it at all. She just does it when she can and moves on." And, someone once told me, "My 2 Labs both like to hump their beds. Often after coming back into the house from being outdoors." Many dogs hump simply because they can.

Where to from here?

There are many studies just waiting to be done on the question of why dogs hump, and I look forward to them. It's time to stop putting out misleading and oft-repeated myths about why dogs hump, because we really don't know. When someone asks, "Why do dogs hump?" the best you can do is to say that there really is no general explanation and ask them to explain the specific instances when they do it, as Dale did, and hope that more detailed data from systematic studies will be forthcoming as soon as possible.