One of the most challenging aspects of developing a new breed of dog or helping to increase the numbers of rare breeds are genetic problems. These genetic problems may be caused by a situation known as inbreeding, also sometimes referred to as line breeding. Contrary to what many dog owners believe, some breeding of closely related dogs may not only be acceptable but may also help resolve some previous genetic conditions, although it has to be done very selectively and carefully.
Inbreeding has always occurred in the wild dog populations and even in the modern day wolves, coyotes and other canine species. Think of the wolf pack as an example. We know that there is one dominant male, the alpha wolf, that breeds with all the females in the wolf pack to pass on his strong genetic heritage. Within one year or less of his first breeding within the wolf pack, his own first litter daughters will be coming into heat, and he will breed with them as long as he is the pack alpha male. Typically in the wild wolf pack some females leave, alpha males are replaced every few years and other males do breed with females, providing some genetic variations and preventing the gene pool from becoming too similar.
However, wolf packs that are isolated geographically may not have these options and the result in many generations of breeding within the same genetic pool. When this occurs the opposite of hybrid vigor begins to become visible in the pack. The result are pups that are born with serious and even fatal genetic conditions, poor growth, poor disease resistance and physical problems that eventually will lead to the extinction of the pack. Females and males eventual become infertile with inbreeding, resulting in the death of that particular group or pack. It is important to realize that this doesn't happen within one or two generations, rather it takes multiple generations of inbreeding to create the negative physical and genetic problems that cause the very serious damage to the survival of the pack.
Before genetics were fully understood, breeders wishing to enhance or develop specific types, traits, temperaments and appearances of dogs commonly used inbreeding. While not as frequent of a practice today, inbreeding can still be used, in combination with genetic testing and monitoring, to actually enhance and even allow the survival of very rare breeds of dogs. Typically these types of genetic issues are handled by researchers, however with genetic and DNA testing more accessible to breeders some rare breeds are making a comeback in the private breeding sector rather than through government or researched based programs.
One of the biggest challenges that has faced even the common breeds of dogs let alone the rare is the fact that breeders are always looking for the dog that most closely meets the breed standards. When this prize animal is produced, the natural tendency of the breeders working with the breed is to use that stud dog in as many breeding programs as possible. When this happens the genetic lines can easily start to converge since the exceptional stud has been used in so many different kennels and lines. Programs such as artificial insemination has both helped and contributed to this problem. It has helped by allowing new genetic lines to be used from dogs that are physically very distant. This is accomplished by selective insemination and the use of frozen semen. In this helpful aspect dogs from different parts of the world that are very similar in appearance or even lineage to the rare breed can be used in breeding programs, plus the semen can be collected and stored for years, far outlasting the actual breeding span for a dog.
However artificial insemination has also somewhat contributed to the potential problems within pedigree lines as well. The same technology allows semen from grand champions over the globe to be used in any breeding program anywhere else in the world. As the breeding lines become used more commonly all over the world, there are fewer lines that do not contain some ancestory from these champion dogs. The good news is that the genetic deterioration from inbreeding with minor close breeding is not a problem unless the dog has some problematic condition. With modern DNA tests available prior to breeding this issue has become less of a concern with breeders than ever.
For rare breeds, selectively adding new genetics to the gene pool within the breed is essential. Breeders work to find dogs that appear physically the same as the rare breed or that might be descendents of the rare breed. For example if the rare breed was used as a foundation for a modern breed or a common breed, breeding the original rare breed to the new breed may be a good option as there are some genetic similarities. Of course if the resulting cross dramatically changed the appearance, temperament or behavior of the offspring of the cross it would not be continued.
Geneticists and researchers often work very closely with private breeders and vets to ensure that inbreeding is done correctly. They can also map and type the genetic possibilities that may be produced by a given cross, meaning that many of the possible recessive genetic issues can be avoided. Recessive genetic problems are the most serious since a dog will be a carrier if it only has one of the "bad" genes, inherited from either the mother or father. If both parents contributed a "bad" gene then the puppy would exhibit the condition. Responsible breeders now know that if one puppy in a litter shows a recessive genetic condition, then all puppies in the same litter and in any further or past matings between the same two parents need to be taken out of breeding programs. Rare type dog breeders are hyper aware and vigilant to these types of situations since with an already small gene pool a recessive problem could potentially wipe out the breed once and for all.
Inbreeding for specific traits is never considered a first choice, regardless of how rare the dog may be. In cases where it is deemed essential or the only option, breeders need to clearly understand the implications of these types of breeding programs, not just for the short term but also for the long term health and genetic soundness of the lines.
Other articles under "Rare and Unusual Dog Breeds"