There's also a third option of sterilization (vasectomy/tubal ligation). Then you can get the benefits of sex hormones without the risk of oops litters. The more research that I've done the more I'm leaning towards doing a vasectomy for my puppy who's coming home in about a month. I'm planning to do agility and dock diving so I want to limit the risk of knee injuries. Plus a bunch of other reasons that I can't remember off the top of my head.