Unless they are trained and disincentivized, dogs of both sexes, both neutered and intact, can and will hump anything in their immediate vicinity. Male dogs hump other males for a variety of reasons, including: Non-sexual play as puppies. Social interaction as they reach maturity. read more
Puppies begin humping each other early, and if it's not trained out of them, the behavior can develop into a habit or signal serious medical problems. read more