Like many canine behaviors that we humans find annoying, inconvenient, or embarrassing, dog humping is a perfectly normal behavior. And like other such annoying, inconvenient, and embarrassing behaviors, it’s perfectly reasonable for us to ask our dogs to stop, or to at least reserve the behavior for times or places that are considered more appropriate by the human family members.
So why do dogs hump? Reproduction aside, the most common reason dogs hump things is in response to stress, anxiety, and/or excitement.
Entire article: https://www.whole-dog-journal.com/issues/17_15/features/Dog-Humping-Behavior_21156-1.html?ET=wholedogjournal%3Ae222912%3A821510a%3A&st=email&s=p_Grabbag061916&omhide=true&t=article1
