
There isn't a simple answer to your question. Age is not the only criteria you need to take into account, in fact I would say that 4 years old is too old to start out on a stud career, unless you are very experienced in handling matings.
Have you organised all the health tests needed for Boxers? Are the results better than average? Is Dudley an exeptional specimen, winning well at Championship show level? Are the people asking to use him well known successful breeders? Are you prepared for a possible change in Dudley's tempament after he has been used at stud.
There's lots to consider isn't there.
Dawn R.