
I have dogue de bordeaux's and have had an interest in them for 7 years, to be honest there are a LOT of Dogue de Bordeaux males out there that have the full equiptment required, I think it would be very hard to find a reputable breeder that would use your dog, he would also have to be hip scored, elbow x-rayed, eye tested and heart and preferably thyriod tested, there are hundreds of male bordeaux that have had a level of health checks done, some quite sucessfully shown that are not getting used at stud as people with good bitch's have such a wide choice.
I would keep your dog as a pet as you have done for the past 4 years and enjoy him, once used at stud a male can change temprement, it it may alter his personality.