This is a great blog post -- helpful to anyone who has an intact male for any reason, including those waiting to neuter a male til he's a year old or so. Also very good on why dogs start to do some of those behaviours that drive owners crazy! :

And also a bit of a reality check for those uncertain about whether to neuter. This trainer clearly outlines the challenges that will be there for life, and the responsible management needed. This should help people in making decisions.