I inherited an entire male who is nearly 18. I didn't want to put him through the trauma of a GA at this age to have him neutered. I am very careful to keep him away from my girls, when in season. He is though still very keen and is the early warning system, when they are starting, where my boys are only interested when they are right on. Is it usual for them to still be keen at this age, (none of my others have ever made it to this age) or is he just a bit different. He is still very fit and active.

Did he use to be a stud dog?

TBH at his age if he is still getting excited for his health I would have him stay somewhere else if you can whilst your girls are in season the old dear could have a heart attack through the excitement, totally off subject but I once had an old guinea-pig who dropped dead from this very reason.

You know that saying, 'there's life in the old dog yet', where do you think it came from? :-D

Yes ,he was a stud dog but hasn't been used for at least 8 years. I just cant believe that he is still so interested.I'll just keep them separated when necessary. I couldn't let anyone else, even the family, have him as it took him quite a while to adjust even to being here, even although I saw him every day in his home environment.

I know of a 14 year old dog who sired a litter unexpectedly, and I don't think he had ever been used..