Your dog is too young. He should be at least 2 years old. Here are some other things that need to be done.
Before deciding to breed a mastiff stud dog or bitch , the breeder should be confident that their mastiff is a good example of the breed in both temperament size and confirmation and dose not have health or temperament problems that can be passed on to their puppies.Health problems that should be tested for are Hip and Elbow Displacia , Heart problems, genetic eye problems , and thyroid . Many reputable breeders go even farther and do testing for many more genetic health problems.If you are thinking why bother testing , I will tell you that from a monetary standpoint you do not want to be refunding money to unhappy puppy buyers because their pup has Hip dysplacia or a bad heart. You could go broke really fast , You may even find yourself in court over an unhealthy puppy. Your goal as a breeder should always be to produce a healthy , sound, friendly, mastiff, of outstanding breed type.You can contact you local veterinarian and he can make all the arrangements for the testing you should do before breeding your mastiff.If you are thinking of breeding your mastiff to make money let me show you how wrong you can be.First of all you will need to factor in the cost of buying a breeding quality mastiff , you are looking at paying $1800 to $3000 dollars for a mastiff puppy from a breeder who dose genetic and health testing on their lines . . Then the cost of caring for that mastiff for 2 years before you can breed the mastiff.Then you are looking at about $700 dollars to do X-rays on hips elbows , eye testing , and heart and thyroid