How do I curtail the frequent "marking" of a 3.5 yr. old male (neutered) pug. We also have an 11 yr. old male (neutered) pug. This 3.5 yr. old male marks everywhere: anything left on the floor, sometimes chair legs, laundry, dog beds, bannisters, etc. He is in good health, all shots current! Sometimes does this in front of us, often when we are out of sight! Is this male dominance? What can be done?