My dog is peeing on the female

Question
My doberman (around 9 years old, neutered at birth by mother stepping on testes) has recently started peeing on our female shelter mix (around 1 year old, spayed).  This is a new behaviour.  Any idea what might be causing this new dominant behavior?

Answer
I often suggest a vet check for changes of behavior in older dogs, but hesitate this time.  Has he been obedience trained?  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat.