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Selective Breeding


Selective Dog Breeding Why? / Why Not?

Have you ever wondered why your Pit Bull follows you around the house like a shadow? Or why your AM Bully can't resist going over to your neighbor's backyard and exploring? Or why it seems that your golden retriever could play fetch with a stick for hours on end? Your dog naturally seems to have certain personality traits. The reason is selective breeding. Selective breeding means breeding an animal for a certain purpose or trait. -Which we will further explain later in this article.

Selective breeding (also called artificial selection) is the process by which humans breed other animals and plants for particular traits. Typically, strains that are selectively bred are domesticated, and the breeding is normally done by a professional breeder. Bred animals are known as breeds, while bred plants are known as varieties, cultigens, or cultivars. The cross of animals results in what is called a crossbreed, and crossbred plants are called hybrids.

In the same way that inbreeding among human populations can increase the frequency of normally rare genes that cause diseases or other birth defects, the selective breeding that created the hundreds of modern dog breeds we have today has put purebred dogs at risk for a large number of health problems, affecting body, temperament, health and behavior.  Inbreeding too frequently or incorrectly (sometimes loosely referred to as line breeding by inexperienced breeders) doesn't just double the chances to increase the risk of these unwanted genes, it actually compounds it dozens of times over and over again!

It’s a common conception that all dogs are believed to have descended from wolves. Kim Campbell Thornton's recent article "Looking Back to the Beginning", describes research that has determined, through DNA mapping and scientific genome research and technology, that today’s dogs regardless of breed likely descended from only a few very closely related ancestors. Although Thornton notes the difficulty in accurately dating the exact emergence of any specific breed, it is apparent that over thousands of years of “evolution”, mankind has, through selective breeding both intentional and unintentionally created hundreds of different breeds and breed variations from a surprisingly small gene pool of original dogs (wolfs).

Some conditions are directly related to the features breeders have sought to perpetuate among their dogs. As they deliberately manipulated the appearance of dogs to create or accentuate physical and behavioral characteristics that were considered aesthetically pleasing, like the flat face of a bulldog or low-slung eyelids of a Bloodhound. However, in the process, breeders have also created physical disabilities in their breeds.

The excessively wrinkled skin of the Chinese Shar-Pei causes frequent skin infections; Bulldogs and other flat-faced (or brachycephalic) breeds such as the Pekingese have breathing problems because of their set-back noses and shortened air passages; Bloodhounds suffer chronic eye irritation and infections and so on.

The unnaturally large and small sizes of yet other breeds create even different problems. For example, toy and miniature breeds often suffer from dislocating kneecaps and heart problems are more common among small dogs. Giant dogs such as Mastiffs, Saint Bernards, and Great Danes are nearly too big for their own good. Researchers have found a striking correlation between a dog’s large size and a frequency of orthopedic problems like hip dysplasia. Large dogs are often prone to heat prostration because they can’t cool down their bodies (tiny dogs, by contrast, have a hard time staying warm), and because of the massive weight they must support, these breeds are prone to malignant bone tumors in their legs. Meanwhile, the huge head and narrow hips of the Bulldog can necessitate that their pups must be born by Caesarean section.

Other health problems among purebreds are the product of both inbreeding and bad genetic luck. The genes responsible for many genetic diseases are “recessive,” which means that two copies of a damaged gene, one from the mother and one from the father, must be present in an individual for the disease to occur. Individuals that carry only one copy of the disease gene don’t have the condition, and are carriers of the disease but are not affected by it. Normally, because recessive genes are relatively rare, it is unlikely that both the mother and the father will be carriers and even less likely that they’ll both give the disease gene to their offspring. But that’s not the case for purebred dog breeds, where genetically similar individuals are intentionally mated, increasing the concentration of recessive disease genes. It’s like stacking a deck of cards with ten extra aces and ten extra face cards; the loaded deck increases your chance of hitting blackjack in a game of 21, but when breeding animals, what you “win” might be allergies or a predisposition to cancer!

When an interesting or useful trait is identified in a dog, owners would breed from that dog in the hope of the trait being passed on. Over many rounds of such breeding attempts, especially where two dogs with the same trait are bred with each other, traits became "Fixed".  If you understand the genetics, you can predict what you can see in a crossbreed or in a litter of puppies from two animals that have "Fixed" genes.

There are over 400 breeds of dog in the world and all are maintained as pure-bred stocks through selective breeding, which aims to maintain a closed genetic lineage. Most dog traits follow simple genetic rules.   Some unscrupulous breeders will even breed back into a purebred dog, one of the orignal different breeds that make up the new breed at hand and think that they are doing the new puppies a favor by strengthening a certain physical characteristic. 

However, such a thought could not be further from the truth.  In actuality, when a breeder does this, they have not only broken the "Purebred Lineage" irregardless of rather or not the new breed had the original breed in it to begin with, simply because that have RE-introduced a new, stronger percentage of DNA than what currently makes up the current purebred that's being bred....  They have now also re-introduced any BAD physical traits, behavioral problems, birthing defects or diseases that may have possibly been breed out through means of RESPONSIBLE selective breeding!   Therefore once a purebred is established, one should NEVER re-introduce ANY other breed of animal into the breeding program, even if the new animal being bred into the breeding program was form the original stock of DNA...  it is ALWAYS a bad idea,  and irresponsible breeding practices to do this... 100% of the time.


Traits are often referred to as being dominant or recessive. Just like humans, dogs have two copies of each gene (one inherited from mom and one from dad), but the letters making up each gene can be slightly different. If a gene influences for a particular trait (such as hair color) then even the slightest differences in the letters in a gene can result in differences in hair color in that animal.   Such as when the American Bully first emerged on the scene after having bred Pit bulls with English Bulldogs. The Tri-Color is a "FIXED" gene carried by the English Bulldog and when it began to emerge in the Pit bull, the dishonest breeders were claiming it to have been a "recessed Gene".

None the less, the breeders at the time that were still passing the litters off as purebred Pit bulls or AM Bullies, when in all actuality they were selling nothing more than the worlds highest price tag crossbred muts to have ever existed.In another article, we will touch on this in more depth explaining the correct way to create a new dog breed and explain why it is essential that there has to be a period of time when creating a new breed that the litters produced wll in fact be nothing more than crossbred muts.   But we mention this here because in times of creating a new breed, selective breeding could never be more important and vital to understand.

Some of these physical and behavioral differences resulting form selective breeding will dominate over others, so that particular variant of the gene is described as being dominant. In this case, the hidden trait is called recessive. When crossbreeding one purebred dog into a breeding program with other purebred dogs you will have pups that inherit two genes for a recessive trait and when the litter drops, you get a surprise when!


Some example traits and their dog genes:

IGFR1: A common recessive variant in this gene can result in a small dog, but only if two copies are present.

FGF4: A variant letter in this gene has the dominant effect of shortening leg length, so any dog with one copy from either mum or dad will have short legs.

FOXI3: Causes hairlessness and also affects teeth, commonly seen in hairless Mexican, Peruvian, and Chinese crested dogs. In these cases the dogs have one copy of the mutant Foxi3 gene, which means that they have one copy of the normal gene as well. Dogs with two copies of the gene do not survive, so we never see these. If you breed two hairless dogs, some of the offspring will actually inherit two normal genes and will have normal hair, for example, for Chinese crested dogs these are called powder-puffs.

Selective breeding not done the right way and for the right purposes by an educated and trained breeder consulting the advice and expertise of a State Licensed Veterinarian can have some pretty adverse health effects on the breed and the future of the breed after that point.

Sadly enough, when a selective breeding does go wrong, it would be the responsibility of a responsible dog breeder to spay or neuter the entire litter of that breeding so that the future of that breed does not become subject to an experiment gone wrong!




Selective breeding happens like this:

You have a litter of puppies and you need dogs to herd sheep. The first step would be to take that litter and put them around the sheep to see which dog pays the most attention to the sheep, even if that's all they do is pay attention to them. The second step would be to breed that dog to another dog that also paid the most attention to the sheep. 

You would then continue this practice for several generations of breedings.  The third step would be to start breeding from the dogs that paid the most attention to the sheep,  a selection of puppies that showed an eagerness to interact with the sheep, perhaps even specific puppies whom seemed less afraid of the sheep.  The fourth step would be to begin selecting puppies form this stock that had the highest drive, or physical stamina, etc thus Completing the process of breeding until you have finally reached all of the physical and behavioral traits that you desire for your new breed of sheep herders. 

This process can easily AND SHOULD take as long as seven to ten, perhaps even twelve or MORE generations of breeding to finally establish your preferred stock for your new dog breed.  ONLY THEN can you begin the journey to actually creating your new breed by being able to consistently breed these same characteristics over and over again INTENTIONALLY for about another three to five generations of intentioanl, selective breeding getting your desired traits EVERY litter and on purpose.  ONLY THEN have you correctly created a new breed of dog through selective breeding.

Animals are also selectively bred for physical characteristics. For example, you might breed only the biggest dogs to the biggest dogs, or only longest- haired dogs to longest-haired dogs.

Wolves were valued for their aid in hunting, guarding, herding, and as companions, therefore wolves were domesticated and became dogs through a process of selective breeding over 400,000 years ago. Dogs (Canis lupus familiaris) are a subspecies of wolves (Canis lupus).

Dogs were bred for certain functions, such as hunting, retrieving or herding. Bernese mountain dogs, with their thick coats and strong limbs, were bred to guard herds and flocks in the mountains. Bloodhounds and basset hounds, with their natural talent for following a scent, were bred for scent-tracking jobs. Greyhounds, with their slim bodies and long legs, were capable of great speed and thus were bred for racing. Rottweiler’s, with their strong bodies and naturally assertive personalities, were bred as guard dogs. Each breed has a specific job to do.

Whatever your reasons for selective breeding (which we feel is always the most professional way of breeding), you should always consider what other methods of breeding you and other breeders have already tried and what the outcome was. What will you do different?

Selective breeding isn’t always bad, providing the dog breeder understands what he/she is doing and is humble enough to realize that he/she doesn’t have all the answers!   It is ALWAYS best to consult a Veterinarian and conduct specific disease tests on both dogs considered for the breeding. Another crucial thing to consider is to refer to any DNA registration or information you have on both dogs. It’s never wise to continuously inbreed dogs of the same lineage (bloodline) back to each other repeatedly.   This is actually very irresponsible breeding practices and it is a clear indication of the breeder putting his/her own interested BEFORE the well being of the dogs being bred.

One should always be careful so as not to make the mistake of an inexperienced breeder and breed for the SOLE purpose of liking a dog’s physical appearance. Doing so is irresponsible and unsafe for the potential health of the litter that would be produced. Only a breeder motivated by sheer greed and money would ever perform a selective breeding for the pure purpose of physical appearance alone. A truly responsible breeder would never breed for looks alone and would always consider the weighing of benefits vs adverse side effects of breeding two dogs together.

At the end of the day, you need to be able to ask yourself, did I show more love to my dogs today through my breeding program and the future of this breed, or was I more concerned about my rise to the top and chasing popularity and money?  If you can't be honest with yourself about this, you have NO business breeding any animal, for any purpose.


Reference Material:
UBKC
PBS
Wikipedia, (Wikipedia.org)