I have an intact male dog (Philippine native dog/Japanese Spitz). He never marks in the house. I have to watch him when we go to 'new' places to see his reaction, he sometimes would attempt to mark if he hasn't been there yet and there were other animals messing the place up (i.e. near the cats' litterbox), but a single "No," will stop him. The only time he 'does' something in the house is recently after we got a paper-trained Shih Tzu. I guess he felt like going and we couldn't take him out yet (freezing outside and he has a cold) so he went to the newspaper and peed there. That was it. If I tell him not to do it, he won't.

And although he isn't 'protection trained', I would assume this is a similar thing--he obeys the 'come' command around females in heat. He actually comes back to me if I call him when I see him running towards the female in question, although he does hesitate for a second. The fact that he can do this and he's a spitz and not a herding dog (which I would assume performs commands better) will tell you that as long as you're in control, your dog won't do anything you don't want him to. Theoretically.

IMO, if you don't intend to "title" the dog (or otherwise prove his breedworthiness) and/or just don't intend to breed, then by all means neuter him after he's full grown (I agree strongly that you should wait).

I've seen what happens to even a well-trained male dog around a bitch in heat--OB goes out the window unless you've specifically proofed the dog for OB under that distraction, which is not easy. And he may live a bit longer.

I have owned three male GSD's and never had them nuetered because I saw no reason to, plus none of my males have ever marked the house even though we had company come and bring their pets with them for a visit. I, imho, would not neuter unless it was absolutely necessary.

Hmmm, I wonder--does a neutered dog lose interest in females in heat when it is done once full grown? I know he doesn't lose the marking thing. Will he lose interest even when he knows what the smell of a female in heat is and erm...has been a stud dog already? I would assume it would decrease his libido, but I haven't observed dogs neutered at this age yet and I have no clue what would happen.