inbreeding in today’s pet dog

INBREEDING IN TODAY’S PET DOG

dna inbreeding in today's pet dog

Today i will speak about a very hard and contested topic. People who gravitate towards dogs affairs have surely heard something about inbreeding, moving between half-truth and popular beliefs.

Let’s start with a little grounding in genetics, to explain his basic concepts to whom is not very well-versed.

We all know what DNA is, a set of chromosomes, set up of couples of homologous in which one comes from mother and one from father, and they contains homologous too pairs of genes, which describes each characteristic of the subject owner of the DNA, from the color of the eye, to the size of the ears, to the behavioral tendencies, to the growing up speed and so on, everything about the subject, is written in the DNA.

I suppose every one had too heard about dominant and recessive genes, in few words, dominant genes are the ones who let us see their presence in the DNA only looking to the phenotype, and who are able to hide the possible presence of a recessive version of this gene. Phenotype, we can say, is what we can observe about the subject without reading directly his DNA, and “read DNA” today is possible. So if in a couple of genes describing, for example, coat length, we have one “long coat” and one “short coat” gene, we will have a short coated dog, but he can be able to generate long coated sons if bred with another long coat carrier, or directly with a long-coated dog. And when we have a long coated dog we will be sure of which couple of genes he has in this LOCUS (locus is the position of the gene in the DNA), in this case we will have surely 2 long coated genes, but we can not be sure of what we will find in a short-coated dog’s couple of genes, because the phenotype it’s the same in the case of homozygousis (2 genes of the same type, in this case, short coat) or heterozygousis (one short coat and one long coat), because, as wrote before, short coat is dominant over long coat, and hides it’s presence.

What we can see in phenotype, it’s not and not always what is described directly in DNA, in some cases and more for some characteristics rather than others, environmental influence can change too phenotype of a subject. Behaviour and character it’s the most influenced trait of evolved species, and the more it’s evolved the more it’s influenced by what append during the growth process, as we born immature and we grow up in a place, learning risks and opportunities, and learning behaviour rules from adults. But there can be also accidental events, such as for example, if a pregnant mother will assume thalidomide during pregnancy, depending from which week of pregnancy she will take it, the baby can be affected by malformations, usually Phocomelia, and we will never know if it’s a genetic problem, or if it’s an environmental problem, without reading directly his DNA.

DNA have been almost completely sequenced today, and we are able to interpret it, we can test directly genetic diseases, to avoid dangerous matings, it could be possible also for humans but it’s not ethic to ask a person to not have child…

But… from the beginning, from when animals have been domesticated, inbreeding has been used.

NATURA SELECTION, survivor of the fittest

Natural selection it’s a process for which only the fittest will survive, or better, they will be more probably the ones who will give birth to new generations, passing them their genes. The fittest are supposed to be the better armed to live in that place, i mean in a certain place, with certain conditions and in a certain period, but these conditions may change as years go by, and as ambient will change, also the subjects fitting conditions will change too, this is evolution.

Let’s talk about an example of what can be evolution of a species. If we look to all the animals living near earth’s pole, they all are white-coated, because of it’s the more mimetic coat color for this region, full of snow and ice. By the way, sometimes a dark coated animal will born, and this append for a new mutation, or for a meeting of recessive genes passed by parents to a newborn. Well, it’s obvious, this subject will not live a long time, or even in a easy way, dark predator on a completely white scene will be easily discerned by prey which will hide in a safer place in time, and a dark pray on a white scene, will probably be eaten easily, and in both cases they probably will not have sons, they will not pass genes to new generations. But if for global worming the snows begins to dissolve from lands, the situation will be inverted, white are now not the fittest anymore, darker animals becomes the fittest, and in a few years we will see dark coated individuals increase in number, and white ones become fewer.

This is the reason why in more evolved species, we have sexual reproduction, nature, who looks to the species and not to a lone individual, during evolution, rewarded this kind of reproduction as it’s the better for grant survivor to a species, during long periods in which planet hearth has dramatically changed his environmental conditions. But sexual reproduction it’s not the only way in which genes are mixed while passed to new born, there is also another phenomenon called crossing over, which increase the mixing of genes coming from father and mother.
dna inbreeding in today's pet dog
DNA is formed by two redundant sets of chromosomes, one set coming from mother and one from father, when gametes will take form (sperm and eggs), one of this 2 parent’s set will be present in to this cells, but this is not completely exact, because during the phenomenon called meiosis, 4 half DNA set cells will be generated starting from one full DNA set cell. In a certain moment of the process, homologous chromosomes will get closer one upon the other, and a little piece of them will reciprocally exchange. So if, for example, in the DNA side of the mother we had blue eyes genes, and in the DNA side of the father we had brown eyes gene, after meiosis we will have an egg with father’s DNA side, but with mother’s blue eyes gene, OR mother DNA side with father’s brown eye gene.

And that’s not all, species evolution is also caused by random genetic mutations. Each time the DNA replicate itself, and it means every time cells replicate itself, an error can occur, and if the error occurs during meiosis, the DNA mutation will arrive in gametes, and then in the newborn’s DNA, and from there, mutations will too can be passed to new generations by the new subject, owner of the new DNA with the new mutation.
As they occurs randomly, mutations may involve any trait of an individual, both in physical characteristics or behaviour tendencies. Mutations, can be illness, disorders, and in this case probably the subject will not live long, or not have progeny, mutations can rather be irrelevant for life, and the permanence of those mutations in species depends from other subject characteristics, or at last mutations can be useful, beneficial for life, and the subject who carries this mutation will probably have more sons, and start to spread the new mutation around the species. Only one above 100 mutations will see light with a newborn, our body usually tent to destroy “errors”. A new useful mutation will take place on a population in a stable way in about 10000 years, so evolution it’s a very slow process, in which species become more suitable for living in a certain situation.

In the same lack of time a mutation take place in a stable way in wild species, men fixed a lot of mutations in dog’s genome. Every time a new interesting mutation takes place, interesting it means for a certain breed’s function as working auxiliary for a dog owner, men fixed the mutation. For example dachshund’s Achondroplasia, dwarfism, is useful to send dog in harmful animals lairs to kill them, but can you imagine a wild wolf trying to catch an elk with 5 cm long legs? Impossible, and this is the reason why some mutations will not take root in wild wolves. But similar mutations occurs in each species, even cats or humans, as you know, they are redundant, like a lot of other mutations . For example, Degenerative Mielophaty, the involved gene was discovered in dog, as it’s the dog’s version of ALS, and it involves the same mutation in the same locus on the same gene.

Now, in the DNA of a certain animal we can find hundreds of mutations related to health problems, which we didn’t know the existence of, and usually this mutations are all recessive upon healthy gene version. The reason is simple, when a fellow born with a dangerous and dominant mutation, he will probably not survive, or maybe only not have the chance to reproduce, for a heavy disability, so the mutations born and die with him. Only recessive health problem’s gene will go ahead through DNA’s generation… and sometimes comes out when two “carrier” of the bad gene will meet. This append because good version of the gene is able to compensate the presence of bad one. When the bad one it’s not visible on the phenotype we speak about complete dominance, and it’s incomplete, when the the subject it’s healthy and can live in a good way, but the bad gene let’s see something in phenotype about his presence, for example, in blue Merle gene, you know how is double Merle phenotype, well, this is the real gene’s phenotype, and when in a pair we have only one Merle gene, we see the effect on the dog, but he’s healthy. This is the better case for a illness, because of we are able to not breed two carrier together without test DNA.

But let’s return to speak about how man would take place of nature in domesticating and breeding species, deciding which mating do or not and why, pushing selection towards what was suitable for a certain role to play for a working dog.

And so here we begin to speak about inbreeding!

As we wrote a few words ago, men works to fix some wanted characters using inbreeding, in domesticated species, now we are speaking about dogs, but the same concepts are good for all species man can breed. It’s easy to get homozygous for some genes couple, mating together two related animals. As they share one or more subject not far in the pedigree, they may share too identical genes versions. Well, remembering what we wrote before, as genes arrived from mother and father, mixed to offspring, we can not be sure of which couples will be homozygous and if any of this couples will be one of the researched quality we are trying to fix, or rather one of the hundreds of illness hided in their DNA! And as those genes usually are recessive, with inbreeding, we increase also the chance to have affected dog for some defect or health problem.

When a new breed needs to be created and fixed, usually we start with one or a few subjects, so it’s almost impossible to have a good number of elements to start with, without using inbreeding, but after a starting program, i think to persevere in inbreeding, by every breeder and constantly, it will be dangerous, and not a good idea!

For sure, someone before us, in the past generation, did it surely wet, and not only once time. We only need to look to a random pedigree and go back for some generation to prove it, we will surely find not far an inbreeding mating. Another usual behaviour of modern breeders, is to use all the same famous stud on their bitches, to better be able to sell pups, as they are son of a “superchampion”, but this is very dangerous, for two reason: all those related matings, and all using the same stud, so in any pedigree we can find it once, twice or more, will take us to a terrible bottleneck, and a hard loss of genetic variation. And if the famous stud carries a problem, it will be spread around the breed! And those things append, we know it!

I remember what an old, rough but expert breeder used to claim often: Sometimes you need to mate a bitch with a bastard, or your bloodline will destroy. And we are speaking about a breeder with a lot of dogs, who usually do inbreeding and line-breeding with his bloodlines , as only a few person today are able to do. Once selection were more practical, to grow up dog really useful to perform tasks for real, as auxiliary for a real work, such as herd sheep for job, and not buy a few sheep to test “Sunday sheepdogs”, with included a great barbecue to entertain participants, as today often append!
We used to have also big breeders, with a lot of money and free time, really enthusiasts to breed their dogs for passion, or people using dog for a real work to eat with, and not breeders who’s job is to sell dogs as today often append. When dogs had to be real useful, selection were more stronger than today, yes inbreeding were also used in a stronger way too, but today also the love of people for dogs is different, today they are like another child for us, so we don’t consider ethic anymore, to have bitch giving birth for example, to 8 pups, but to keep only the biggest, strongest, healthier, in a word, better one or two pups. Once the other 6 pups were surplus unuseful mouth to feed! And they were put to sleep, except if someone would ask for one of it! Today is different, we don’t have hearth to put to sleep “surplus pups”, and we don’t find ethic to breed unhealthy pups, and often those pups are not put to sleep anymore but they will be homed to a family, and it’s not impossible this family will have pups from this dog, because they wants “child” from his sweetheart, and this is not a good idea!
So, with inbreedeng, we run more risks, and we have to know it! There is a higher chance to have unhealthy or cripped pups, and we have not the courage to keep alive only the one or two perfect subject, and usually today, when “the experiment” of inbreeding it’s made, to try to fix something, almost all pups are sold like a good one to family, who are not able to understand and read a pedigree, but we can not be sure they really will be good and healthy. Some problems usually comes out only after some years.

Another problem is today’s stud are mated too young, often also before they are 12 months old, when we are not sure of morphology as they are not mature anymore, but also of the character, for the same reason, and of his health always for the same reason, we can not be sure!

Really working dogs are replaced only when too old to work, and mated not a lot of time before they will stop to work, to keep another dog to replace the older one, and in this case, we are more sure of good health and attitudes of the dog we are mating.
For this reason, i don’t understand why we have to do inbreeding to fix… what?And Why? For our ego? Because we are happy if people, will recognize our type, looking to a dog bred by us? The most of those dogs will go to live in a garden or sleep upon on a sofa, and for a family he will be the most beautiful dog in the world, even if is really ugly if compared to world champion. In my opinion, good health and good character it’s the most thing we have to “fix” in pets, And we don’t need inbreeding to do that. Not With the actual pet’s breeding situation, especially for some breeds.

We can also fix our type without inbreeding, by the way, all dog’s of a breed has similar DNA yet, as i wrote before, but if i find subjects with the characteristics i am looking for and mate them, i can reach my target without the use of “hard” inbreeding.
For example, if my goal is to fix a chocolate type of coat, and i have a good chocolate dog, i don’t need to mate him using inbreeding, i can find another dog not strictly related to mine, and use this. Even because, mutations are often redundant, so 3 different DNA mutations were find in dog for black to become chocolate, different but with the same effect, and we don’t need to have homozygousis for one of the three versions to have chocolate coat, we can “sum” two different mutations and we get the same effect, and the tone of the color is not related to a specific mutation, but is regulated by other modifiers genes. I think that only some traits really essential to the function of the breed, needs to be almost identical in every subject, for the other traits, it’s healthiest to have more variation, and less homozygosis, especially if we are speaking about traits useful only to win expos! And not to really to work!
I am not against inbreeding at all, i know it can be useful, it has been useful, but it’s a risk and it has to be taken in the right way. We need to tell what can append to people who buy those pups, or ask to not mate them, or not mate them without ask breeder if it’s the case, after health tests and other verifications, or better we can keep all with us to see what append, and then eventually find between them “the perfect one” to continue our selection with.

It’s not a secret, if we are able to arrive to a healthy and good in working set of dogs, then we can breed them also with line/inbreeding, but the number of subject of a lot of modern breeder are often not enough to do that, if they don’t find other breeders who will work in collaboration with us. And this is another big problem, omerta. As the national sport for breeders is to discredit colleagues, when a problem comes out in a litter, people tends to don’t tell anyone, so it’s not easy to intersect data and find a good couple to mate, without a complete knowledge of what bloodlines are hiding behind.
This is one of the reason why a big breeder with a lot of dogs usually prefer to use his lines, because to outcross with other people’s dog it’s often more dangerous, with this breeding world’s condition.

last but not least, some definitions, to clarify some concepts

INBREEDING DEPRESSION:
is the reduced biological fitness in a given population as a result of inbreeding, or breeding of related individuals. Population biological fitness refers to an organism’s ability to survive and perpetuate its genetic material. Inbreeding depression is often the result of a population bottleneck. In general, the higher the genetic variation or gene pool within a breeding population, the less likely it is to suffer from inbreeding depression.

Don’t forget nobles and their health problem, caused by related marriage.

INBREEDING
We have inbreeding if the parents have a short relation from 2nd to 3th or 4th degree in this two case is called crossbreeding.

LINEBREEDING it’s a mate with two further related

OUTCROSS
Usually is considered outcross a mating, where in the first 5 generations behind the subject, there are not shared related.

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