Our Basenji is about 65 years old, we also have 2 other dogs, a female black lab 6 years old and a male 1 year old Boerboel (Mastiff). They all get along really well with the Basenji being the alpha dog still. I have noticed over the last year that the Basenji will put his rear end in the other dogs faces and jump in the air and hit them with his butt. If this a dominance thing? I have never seen another dog do this, ever in my life. Please advise. We are also going to have a new Mastador pup around Thanksgiving, do you think 3 males will have dominance issues with each other?