Mills61, Many of us here on this forum have run into many different genetic disorders, boxers have a list of problems that can be resolved with proper genetic testing. Many of us learned the hard way by getting a pup from someone who bred their dog because they were so well tempered and good looking. Honestly I have learned that isn't a good reason to breed your dog. Once bred male dogs will tend to wander looking for another plus they will begin to mark, letting it be known they are there and available. I had one start marking in my home many many years ago, didn't even notice it at first until my home had a smell. Then I had to rip out all the carpets, replace them including the pads and I had to paint certain areas. All that and I d isn't even allow mine to breed but a neighbor use to let her female in season over on my property and that was all it took. If you are interested in breeding you can find some information on which testing should be done American Boxer Club: Recommendations For Health Screening Of Boxers In Breeding Program
Best of luck.