The only things I expect a neuter to do is 1. keep my dog from being able to reproduce 2. keep him from getting testicular cancer and 3. hopefully the lack of testosterone helps keep his mind at ease and allows him to feel happy and not in need of controlling his surroundings.
Spay/Neutering for me is not an option only because of my breeding program and how we're trying to increase diversity in our chosen breeds.
And for my clients this option is completely their choice. But when they ask me when is a good time to do so, well my answer is. Its different for each dog. Some will mature faster than others some will take longer than expected.
When they ask me if they should not. The best way to decide on it from my perspective is as follows...
Do you have any reason to think that your dog/bitch would have any positive contribution to add into the existing gene pool?
Is this a fine example of a good temperament with a biddable nature and is it free and clear on any health problems that may show in its offspring?
AND do you have the time to properly aid in whelping puppies?
Are you aware of everything involved in doing so?
If you answer no to any of these..... then you should consider spay/neuter.
If you can't answer yes to all of these then spay/neuter.
If you can answer yes to all of this, then begin searching for a suitable mate from a completely different line. Not a brother or sister, not a mother or father...no cousins and no grandfathers, aunts or uncles. If you plan to be a positive factor and this is not about making money then its your responsibility to do these things. Otherwise you have no clue and should be whipped for considering it.
My advice to anyone would be to ALWAYS spay and neuter your pets if you're not a professional breeder. Take a walk through your local shelters and see all the homeless animals on death row.
Good breeders will always be necessary so we can have high quality purebred dogs and someone who really wants a purebred Tibetan Mastiff isn't going to go down to the shelter and adopt a mutt. But if you're not a professional, please get your dog fixed. Especially in this economy when even the high quality dogs aren't selling as well.