There are many differing opinions as to what makes a dog worthy of breeding. There are certainly plenty of mastiffs in the world, as shown by the large numbers of mastiffs in rescue programs, and the fact that mastiffs currently hold the highest registration numbers of all the giant breeds. We need to carefully consider what a particular dog brings into a breeding program and into the breed itself. This is an ethical issue, and there are no cut-and-dry rules to follow-- it is a decision that should be made from the head and heart. If in doubt, then don't breed-- puppies cannot be unmade once they are here.
A dog should only be bred if he or she has something to offer the breed. There are many mediocre mastiffs, so there should be something special that a dog has to offer to warrant producing yet another litter of mastiffs.
Why breed?? A reputable breeder breeds a litter for something new to show for himself, or to continue on with in their own breeding program. If a breeder is not keeping a puppy from a litter, one would question why the breeding was done in the first place. Responsible mastiff breeding only costs money, it does not make any. Careful rearing, feeding, testing, showing, training, and medically maintaining a mastiff, or mastiffs, is generally extremely expensive. A reputable breeder loses money when breeding, if you look at the big picture of what it took to get to that point. It is cheaper and much easier to just buy a new puppy from a reputable breeder rather than breeding a litter yourself if you want a new puppy. Mastiff breeding is fraught with disaster, mostly costly and mentally -draining disaster! There have been many bitches that have died during late pregnancy, for no apparent reason. Most mastiffs end up needed a cesarean section, and in fact, many breeders just do an elective c-section before the problems occur, since they usually do, in order to minimize puppy loss. Mastiffs are often not good mothers, and tend to either ignore, or innocently lay on and crush their babies. The great size of the dam causes problems as she often cannot feel a baby underneath her, no matter how attentive she may be. Mastiffs cannot be left alone with their babies for this reason, requiring 24 hour care for at least a month. Many of them will not clean their babies, so the breeder may need to stimulate each puppy to eliminate, many times a day. They are extremely messy and high maintenance. They must be kept warm at all times, and the litter cannot be raised outdoors. The bitch has a high chance of getting mastitis, a bacterial infection of the teats, and this can cause death for both mother and babies if not caught in time. Even if treated, the babies generally must be handraised after that point, if they survive at all. Very young mastiff puppies must be tube -fed, as they do not have the strength to swallow correctly from a bottle, and can aspirate-- causing death from pneumonia.
This is standard breeding experience, so if you can handle this misery, read on. Yes, many breeders have first time "luck," and things go well, but generally if things can go wrong, they will. Only extremely dedicated breeders continue to breed, only for that special puppy for themselves. Most first- time mastiff breeders never want to do it again, it is too expensive and mentally draining, and can be very hard on the bitch.
You have determined that you have the time, energy and money to breed your bitch. There are a few things to consider before jumping into the breeding world. Is she a good representative of the breed? Familiarize yourself with the mastiff Standard of perfection, available from the American Kennel Club. Seek out the opinion of several reputable mastiff breeders and discover her virtues and faults with an experienced and unbiased second person as your "eye." She should be completely tested for genetic defects before even considering breeding her. You need to know what your eyes cannot see before determining her suitability as a contribution to the mastiff gene pool. How is her temperament? She should be as the Standard describes, a gentle giant. Shyness and aggression can be genetic, and can also be taught to a litter of puppies before they leave for their new homes, by their mother. There is no room for mastiffs in our world that are not safe and dependable.
How does she physically meet up with the Standard? This is often an area where the consultation with several experience breeders is really needed. Its easy to read the Standard and apply it your dog, and mentally make your dog fit that Standard. But in actuality, does it really meet or come close to that Standard? There is no perfect dog, but there are many facets of dog anatomy that require a trained eye to determine quality.
If you are prepared to take the potential breeding disaster "plunge," you have tested your bitch, her temperament is correct, and you have sought out the opinion of several experienced and reputable breeders regarding your bitch's quality, then you may have the makings of a good mastiff breeder.
As far as the potential stud dog is concerned, many of the same standards apply. No, the stud dog owner has it much easier than the brood bitch owner as far as raising the litter goes. But his role is not complete after performing a breeding. That stud dog's (and brood bitch's) name is on the progeny's pedigree for years to come. An unwise breeding choice can come back to haunt a stud dog/brood bitch owner over and over, and do terrible damage to our breed. Mastiffs end up in rescue (if they are lucky -- not to die alone in a shelter), or worse yet, auctioned off for puppy mills to gather breeding stock, to live a life of misery. The pedigrees often follow these poor animals and one unwise choice somewhere in that pedigree probably caused that dog to be in the position that it is in. Breedings should only be done with bitches that belong to concerned, reputable breeders, and only if that breeding has the potential to better the breed genetically, physically, and mentally. The stud dog has just as much responsibility to the puppies, it "took two" to make those babies. If a puppy ends up in rescue and the breeder cannot or is unwilling to take responsibility for it, the stud dog owner will be expected to step in. A reputable stud dog owner or breeder is always willing to do whatever it takes to help a puppy out of their breeding, or even out of a distant breeding, generations removed. If you had not chosen to breed your dog or bitch, that great -grandkid, or whatever, would not be there.
The same standards for the male do apply-- the stud dog should be tested, have a correct temperament, and be graded by experienced, reputable breeders to determine quality and faults that the dog may posses. Most reputable breeders show their dogs to prove that the quality was seen by many uninterested parties educated in the breed (judges), and that the dog is competitive against other mastiffs. Most highly regarded breeders only breed their champions, or dogs that would have attained their championship if shown. If you are serious about being a reputable breeder, all efforts should be made to show your dog or bitch to its championship. This shows your serious intent and the quality of your dog. Not all champions are worthy of being bred, and not all dogs worthy of being bred are champions. It's just a good rule of thumb to show first, then only breed if everything falls into place as hoped. Some breeders "show to breed," and others "breed to show." There is no wrong or right, just different backgrounds or preferences. But proving your mastiff in the ring is a very good idea, and it also shows interest in the breed as a whole. If you cannot afford the time or money to show, then you certainly can't afford to breed!
Once it is determined that the stud dog or brood bitch is suitable to breed, then more choices come when making potential matches. Just because a dog has testicles, or a bitch has a uterus, does not mean that it should be bred, and just because two dogs have those portions of their anatomy, that they should be bred together. If the potential breeder wants to make the ultimate mastiff for them self, then there are many factors in deciding where to go in that breeding program. Virtues and faults should be analyzed, and the advice of seasoned reputable breeders should once again be requested. One can find common ancestors in pedigrees and "line breed." This method of breeding related dogs together tends to solid up the pedigree, often bringing the virtues and faults together and making them occur more predictably within a line. This may be good or bad, depending on the faults and virtues that are seen. That is where consultation with reputable breeders comes into play. They will be far more likely to share with you what you may expect to achieve with a particular breeding. Breeding to a total outcross (an unrelated dog) may bring more "hybrid vigor," but also may lose uniformity overall. It must be determined what the dog or bitch has that is good, and what that dog needs improvement on, and go from there. It is best not to breed two extremes. For instance, breeding a very "houndy" or plain head, to an extremely "bully" head will most likely result in both extremes, rather than the middle of the road, as hoped. It is always best to breed to the most typical or correct dog, and chose the puppy that closest conforms to the Standard to go on with. Most faults cannot be corrected in one generation-- a good breeder is in it for the "long haul," it may take years to get closer to where that breeder wanted to be.
Try and find out about the parents, grandparents, and so on, with both the bitch and the dog being considered. Find the depth of testing, so you know how far back genetic soundness goes on both sides of the pedigree. Keep in mind that many breeders did very little testing, even just a few years ago, so don't be surprised to find little testing results listed on the pedigree. If one or the other had very little testing in its pedigree, it would be wise to go to a pedigree with lots of testing....it increases your chances of producing fewer genetic defects in the long run. The same applies for all aspects of the dog, physical, mental, everything. A good amount of research should go into a potential breeding, and even so, disaster can occur in spite of best intentions. Most reputable breeders guarantee their show quality stock against genetic defects, and a poor choice, or just plain bad luck, can have repercussions for many years.
Breeding quality dogs is an art and a science. It may be very rewarding, or it can be disastrous. There are ups and downs, to be sure. But making wise and careful breeding decisions at every level can help it be a better experience for the breeder, the dogs involved, and the breed as a whole.