Humping behavior

Question
My older dog Toby has developed a compulsive humping behavior that seems to be triggered by anxiety or nervousness. He tries to hump me when he is over-tired, over-stimulated or anxious. I have tried distracting him with toys and chewies, putting him to bed in a darkened room, time-outs and "no hump" commands, but he always resumes the behavior. He knows he is not supposed to hump, and tries to stop himself but the frustration gets the better of him and if not permitted to hump, he will bark and stare at me. Please help!

Answer
This is an unusual behavior in an older dog without any strong trigger, such as the presence of a younger male or female.  Humping is normally a dominance related behavior (not sexual) and it's unlikely your older Toby is intending it.  This leads me to think that there is some cognitive dysfunction involved, possibly caused by something physical.  You must take Toby to the veterinarian and report these episodes of anxiety and its resultant behavior.  There are medications to relieve anxiety but the dog should undergo a thorough physical evaluation (orthopedic, neurological, abdominal palpation, rectal exam) as well as a blood chemistry.  Meanwhile, when Toby begins this behavior put a leash on him.  The leash is more than a physical restraint to most dogs and often calms extreme anxiety.  Step on the leash to prevent him from assuming any humping pose, if you must, although I think the leash itself will help.