> they can become quite obsessed if they smell that there is a bitch in season somewhere in the locality
This is so very true, and worth emphasising to your friend.
I recently had a visiting bitch to be covered by one of my boys. As it wasn't too far to travel, the bitch was brought a little early, and had the opportunity to "get to know" her boyfriend.
It was on the 3rd visit that it became obvious that my lad was interested, and we had a tie. The other boys had been crated 2 rooms away, to ensure no accidents. The noise was horrific. They all howled for the bitch, and it was obvious that they knew she was ready. How the hell can they smell behind closed doors? But they can, and went wild. You can tell her that it can be a real nuisance.
Tell her the neighbours will complain! :-)