IMO an 8 month old puppy shouldn't be considered a Stud or even a Stud Prospect at best. I honestly would even be wary of a dog twice that age being a stud. That being said, depending on his development, it is possible for him to reproduce. Lifting his leg has absolutely nothing to do with it. There are some dogs who go through life NEVER lifting their leg and they can breed just fine. Also, just because he might not have started to get major amounts of testosterone doesn't mean his reproductive organs and functions won't work properly. Keep in mind that while he might be able to do it, many dogs are not fully mature until they are 3 years old (or more) and there is a LOT that can change both mentally and physically in that time frame. I agree also that a dog and bitch both need to prove themselves before being allowed/permitted to pass their genes on.