Dear Labby,

  We have a one year old chocolate male named Duke.  A couple of days ago, we adopted a 2 year old black female
  from a neighbor.  Both are spayed or neutered.  However, since we've had the female, the young male will not leave
  the female alone.  The poor thing can't get a moment's rest.  She does instigate it sometimes, but the male keeps
  trying to get on her.  How long will this last and is there anything we can do?  We keep getting onto the male, but
  he's only doing what's natural to him.  What do we do??

  New Mom, Kansas

Hi New Mom,

The problem you described has nothing to do with sexuality. Once it is settled who's top dog around your place (which will be very soon if you don't interfere), this problem will have solved itself.

In true sexual behaviors, the mounting behavior only occurs at the very end of the mating dance, and then only if the female has quite explicitly accepted her male suitor.
The fact that mounting behavior can be relatively independent of sexual intentions can be seen by watching very young puppies. Well before they have reached puberty (which comes at about 6 to 10 months of age) they are already showing this kind of activity.
Mounting in puppies appears shortly after they begin walking and appears when they start playing with each other. It is a socially significant behavior, not a sexual one. For young puppies, mounting is one of the earliest opportunities for learning about their physical abilities and their social potential. It basically represents an expression of dominance. The stronger, more authoritative puppy will mount its more submissive brothers and sisters simply to display leadership and dominance. These behaviors will then carry on into adulthood, with the significance being power and control, not sex.
This mounting behavior is used as a signal for dominance and since it is unrelated to reproduction its social significance applies to both males and females. As a display which serves to challenge or to assert social dominance by one dog over another, this behavior can occur between individuals of the same or the opposite sex. A male mounting another male is thus not displaying homosexual tendencies, but is simply saying "I'm boss around here."
Females may use mounting as a statement of social position as well. Females can be dominant over other females and even over male dogs, and can display this by assuming a mounting position. This is not an issue of sexual confusion since the dynamic structure of dog society is not a question of gender alone. Status in the canine world depends more upon size and physical ability, combined with certain characteristics associated with temperament, motivation and drive. In the social structure of dogs there are three different hierarchies.
There is the overall rank in the pack, which starts with the leader at the top and moves down to the ultimate underdog. There is a lead or alpha male and an alpha female, and one of these will be overall pack leader. There is also a ranking among the rest of the males, and another among females. Mounting behavior may occur to assert any one of these rank orders, which means you may see males on males, females on females, males on females or  visa versa. None of these behaviors represent any form of sexual advance or invitation.
Instead they should be viewed as a very clear signal of serious social ambitions by the mounting dog. Some of the dominance expressions that we saw earlier, including the dominant dog placing its head or paws over another dog's neck or shoulders, may well be simply subtle components of activities related to mounting. The dominant or "top dog" is literally the dog that is on top.
Since mounting behavior is most commonly an attempt to claim a higher social than that of another animal, it should not be surprising to find that the belief that you can stop your dog from mounting by neutering him is just a myth. Neutering will eliminate certain sex related hormones in the dog, such as testosterone, and the reduction in these male hormones will tone down the dog's aggressive tendencies and also reduce some of the dog's other dominance behaviors. This it may reduce the appearance of mounting behaviors.
However, neutering will not change the dog's basic character and personality , so in a dominant, leadership oriented dog, mounting behavior may still occur. What the removal of the sex hormones will do is to reduce the intensity with which the dog will pursue his social ambitions. However, the older a dog is when neutered, the less his dominance traits will be curtailed. Castrating a male dog will eliminate his ability to reproduce. Erection will still be possible, but sperm production has been stopped. This means that the dog may still be interested in a female in heat, but any such attempted matings will be literally ''fruitless.''