Ya know, I must just have something wrong with me, but I don't pay attention to my dog's testicles. Actually, I have all bitches now, but I have had dogs, and they were intact, and I wasn't constantly checking if they had arrived yet, or if they were up or down, or if they were placed correctly. Luckily they never got infected because I am not spending my days worrying about them.
But, it seems like nothing seems to get in the way of sperm production. Yes, yes, infection or brucellosis will, but barring that, if the testicle is not removed, treat it as though it is active. Even undescended testicles can be fertile. So my gut reaction is that your boy can reproduce, so please make sure that he does not, unless you are prepared to have puppies, and do all the necessary stuff that comes along with it.
Heidi Ho, Odie
Joy-Joy, Bear Cub, Hepsi-Pepsi
Cujo2, Karma Chameleon
Ramona the Pest, Kojak -- who loves you baby?
Tiny Tinnie, Susie's Uzzi, Kaiah -- The Baby Monster.