I had my Bryan done at 7 months.....all but one of his teeth and fallen out to I had them pull it out while he was under.....At six months exactly he teeth just started falling out every day and he started grabbing my arm standing on his hind legs and humping the air.....It was kind of funny because you could tell he really didn't know what he was doing

 Once I had him neutered he stopped humping the next week
