The male’s testicles should be descended and visible by this time. If they have not descended, or if only one can be seen, consult your veterinarian.
The urge of approaching maturity sometimes causes a male dog to begin the objectionable habit of riding your arm or ankle when overexcited in play. And it’s quite normal for male puppies to mount other pets, children, and even pieces of furniture and become sexually aroused. The best way to deal with this is to grasp the dog by the collar, give him a quick shake, and say “No!” sharply. If he tries the trick on someone or something else, push him away as you give the command.
Because children and dogs like to roughhouse together, dogs unfortunately misbehave in this manner more often with children than with grown ups. Parents should instruct their children accordingly. When they actually see it happening, they should simply say, “Don’t let Rover do that!” There is no need for parents to be embarrassed at such a time, however. Animals are animals, and they often show their sexual feelings, especially before they reach puberty. On the brighter side, once the dog is fully grown, he’ll usually outgrow the habit. If he doesn’t, ask your veterinarian about having him neutered. If you do not intend to use a male for breeding, it is inconsiderate to keep him sexually frustrated.