All conditions and characteristics with which a puppy is born are congenital. Not all conditions and characteristics are inherited, some are acquired. Many conditions and characteristics with which a puppy is born will not become apparent until some future date, although the characteristic or condition was latent or hidden in the younger animal.
Inherited conditions and characteristics (good and undesirable) are able to be passed on to the next generation either as the condition and/or characteristic itself, or in a carrier state. The carrier state indicates that the animal does not show any indication of the condition or characteristic, but that it is possible for it's progeny to have such a characteristic or condition. The easiest to understand example of this is the pure white animal that produces a pure black puppy. Further more, there are several methods of inheritance by which this may occur. There is much documented information of coat colour, but even so, there continues to be genuine anomalies, even with such a basic form of inheritance.
Inherited conditions and characteristics are more likely to show up with inbreeding. This can be a good thing or highly detrimental. If the dogs are carrying genetic faults and/or genetic diseases, these may appear in the progeny if the dogs are mated to close relatives. THere is less chance of them appearing if the animals are not mated to close relatives. This is of course a two - edged sword.
By mating animals that are not closely related, you may produce many beautiful puppies that are carriers of faulty genes, that do not demonstrate that they carry this/these gene/s. In this way a whole breed may become infested with such a gene. Until such time as many members of the breed have been contaminated by such a gene, it may not be apparent that the breed has a problem. By then the problem is so widespread that it will take so much work by dedicated breeders to select a line free from such a defective gene. This will require a great deal of inbreeding with more than a small amount of total culling, that is, destruction not only of affected puppies, but the sterilization of their parents. Normal puppies from these parents, on the off-chance that a few are non-carriers, should be test mated to, if possible, affected partners or al least known carriers of the defect. In the case of affected partners, the production of twelve normal progeny is taken to be about 90% certain that the animal is not a carrier. Of course, the twelve plus progeny will almost certainly all be carriers from the affected parent, so they should all be sterilized to prevent them from passing on the problem. If a young dog was thus tested, it would then be a good idea to offer him at public stud, but not to advertise that he was free from the defective gene, although it would be reasonable to state that he had been test-mated and had failed to produce any defective progeny. The total number should be stated. In this way marked progress could be made in the breed. But do remember that just because the sire is probably free from carrying a defect, it definitely does not mean that his progeny are. They may well be carriers from their dam. Every breeding animal should be tested. If every sire was tested for at least ten generations, there would be a fair chance that the incidnce of the defective gene would be markedly reduced in the breed. Even after this number of generations, it is highly unlikely that the defect would be eliminated from the breed.
There is value in breeding stock that is not closely related in breeds without genetic defects, but in breeds with genetic defects, mating of unrelated stock will be detrimental to the future of the breed, by spreading the carried defect throughout the breed until there is probably no line free from the defect. On the other hand, the close mating of relatives will expose undesirable genes in any breed. Close breeding of quality stock will also produce top class animals that will breed to type with greater consistency than will out-bred stock. However, the close breeding of mediocre animals in any breed will do no more than perpetuate mediocrity.
Acquired congenital conditions happen because of environmental conditions during the bitch's pregnancy. Most acquired congenital conditons are detrimental. If they were favourable, no one would admit that a chance condition had improved the outcome of their breeding plans.
A virus, anything from a mild human cold or flu, through to the distemper virus, may affect the unborn whelp. Roundworms that migrate to the foetal lungs from the bitch may cause all sorts of damage. Chemical contamination through all sorts of fumes in the atmosphere. These sorts of things are usually only trivial and there presnce an hour earlier or an hour later may have no effect whatsoever. Of greater importance is nutrition, not the overall lack os, or the excess of, as much as the imbalance of minerals and vitmains. Too much of this may interfere witht eh absoption of that. It is all very complicated when broken into its individual parts. The best way to tackle such a problem is to use natural products that hopefully have not been processed in a laboratory or have been dehydrated to radically upset trace elements balances. Such additives as seaweed meal, yeast, preferably torula for its extra zinc content, fresh cod liver oil, freshly rolled cereal grains and fresh meat should go a long way in providing a relatively balanced diet for the pregnant bitch. SOme milk will also help. All natural foods have a "buffer" system to prevent the natural absorption or various ingredients. Often this is the only problem with laboratory produced foodstuff for man and beast. This lack of a brake to the absorption and the polarization of synthetic foodstuffs often producing completely unexpected and undesirable results. Just sometimes adverse weather conditions may produce defects in foetuses. This is unlikely and extremely rare, but there is some evidence that it occurs.
Drugs may also play a part in producing defects in foetuses. Always tell your veterinary surgeon that a bitch has been mated if she should need his attention while she is pregnant. Always discuss with him any drugs she may have been on before mating to see if they should be stopped for the duration of the pregnancy.
Finally, if she does produce any puppies with congenital defects, do discuss with your veterinary surgeon any drug/s that she had during her pregnancy. In this way it can be reported and recorded with the National Registration Authority as an Adverse Experience.
All problems with defective puppies are not hereditary, but how can you tell? Some familiar problems that keep cropping up that kennel receives a similar diet in a similar environment, and puppies you have sold have, no doubt, been fed your recommended died, so they too could have the same problem. So start by checking your diet, surroundings (old paint that contains lead is sweet and liked by dogs), the whelping box and its surrounds. If all this is cleared, it is time to test mate your bitch if you do not have a dog. If you believe you have an inherent problem, you should definitely have the puppies sterilized before sale and the bitch should also be sterilized. WHere do you go from here? Try again and again; that is the only way to succed!