
What breed is he? Has he passed all his breed-related hereditary health checks? Is he a good example of his breed (as shown by achievements either in the showring or working)?
Don't forget that the stud dog owner is as responsible for finding homes (and, if necessary, taking back any pups whose homes fail, at whatever age) for the resultant pups, and that being used at stud
can change the dog's temperament permanently.