The male dog’s testicles must be descended and visible by 7-10 months old. If they have not come down, or if only one can be viewed, consult your veterinarian.
The urge of nearing maturity sometimes makes a male dog to start the objectionable habit of riding your arm or ankle when overexcited in play. And it's rather normal for male puppies to mount other pets, kids, and even furnitures and become sexually aroused. The great way to deal with this is to hold the dog by the collar, give him a quick shake, and state "No!" sharply. When he attempts thetrick on someone or something else, push him aside and then give the command.
Since kids and dogs like to roughhouse together, dogs regrettablymisbehave in this manner more often with kids than with adults. Parents must instruct their children accordingly. When they actually witness it happening, they must simply state, "Don't let Bover do that!" There's no need for parents to be humiliated at such a time, however. Animals are animals, and they frequently show their sexual feelings, particularly prior to reaching puberty. On the brighter side, when the dog is completely grown, he'll generally outgrow the habit. If he does not, ask your vet about having him spayed. If you don't intend to use a male for breeding, it is inconsiderate to keep him sexually frustrated.