If you have 2 unaltered males in your house they will mark. In addition once they are marking sometimes nuetering will not stop this behavior and the longer you wait to nueter the more ingrained the behavior will become. Finally, once you start to use a male for breeding they will want to mark all the time. I personally do not see any benefit to using him to breed and take on all the added baggage of having any unaltered male in my home. Is it the idea that you can make money off stud fees? This alone should not be your reason for using him in this manner. I would have them both nuetered for their health and your sanity!
