American Field
https://americanfield.villagesoup.com/p/1787010

The Old Ways, The News Ways, and the Science Supporting the Old Ways

Choosing or Breeding a Hunting Dog

By John Salassa M.D. and Mark Olcott D.V.M. | Oct 30, 2018

Old Ways — Phenotype. Most hunting dog owners and all hunting dog breeders are interested in a dog that is healthy, a good companion, and a good hunter during its expected life of about 10-13 years.

As old age creeps in at 8-10 years minor or even more serious health issues start to slow your buddy down. (When you get to my age of 72, I can definitely say “me too.”) However, for non-injury health issues before the age of eight years we must always ask, “Could this be due to an inherited disease?”

For performance characteristics such as use of nose, prey drive, athleticism, intelligence, coat, flushing/pointing, retrieving and other instincts, owners and breeders are after the best. For a companion, we all want a dog that is friendly, has a good “off switch” in the house and gets along well with other dogs and people (temperament).

All of these desirable characteristics of today’s purebred hunting dogs were developed in the last 180 plus years. Purebred hunting dogs were first developed by royalty, individuals of “means,” as was the sport of hunting. These individuals knew what they liked and simply bred the “best to the best.” This is what science calls phenotype —or how a dog looks and performs.

Phenotype is the outward manifestations of the dog’s genetic makeup. The establishment of hunting competitions or trials in the mid-1800s allowed breeders to compare their dogs to others and gave a measure for the term “the best.” Dogs exhibiting poor performance, health issues and deformities were quickly culled.

The hunting (bird dog) trials led to breed registries and then dog pedigrees, the all-important tool of the breeder. The phenotype, pedigrees and tests were all the early dog buyers and breeders had to work with.

 

THE NEW WAYS — Genetics.  Then in 1866 (“rediscovered” in 1900) along came a monk named Gregor Mendel who studied the inheritance traits of peas and the science of genetics was born. Genes were determined to be the very stable blue print of inheritance.

In the 1950s Watson and Crick discovered the arrangement of genes in the structure of DNA and the science of genetic inheritance exploded.

Environmental influences, not just the DNA blue print, were also found to be critical to the phenotype (the final outcome as an adult).

The balance between genetic inheritance and environmental influences swung back and forth giving rise to the nature (genes) vs. nurture (environment) debates as to how we, people and dogs, ultimately turn out (phenotype).

During the period of 1950-2005 genetics (nature), seemed to have prevailed over environment (nurture). Specific genes were identified that caused a given trait or disease. The complete human and purebred dog genome (gene sequencing) were identified. This is currently under intense study for both people and purebred dogs. People because it’s us, and purebred dogs because, being purebred, they have less gene variation, which makes finding genes for a trait or disease much easier.

Thus many genes that give rise to a trait or disease have been identified both in people and dogs resulting in a genetic marker. (Unfortunately, at this time, performance genetic markers have not been identified.)

These genetic markers have proven to be both a tremendous asset to dog breeders and owners but also have led to misunderstandings as to what this information means. Various companies now offer genetic panels for specific known diseases or traits in “dogs.” The problem with these tests is that they are sometimes very breed specific.

This means they are meaningful only in certain breeds and not in others. Lowell Atkinson DVM in his book “Inherited Health in Purebred Dogs,” states that veterinarians can “no longer practice canine medicine but instead must practice breed specific medicine, Labrador Retriever, Golden Retriever, Boxer, etc. medicine.”

Each pure breed has its own set of inherited traits and health issues. As a responsible owner and breeder you should learn your breed’s inherited traits and health issues.

THE NEW SCIENCE SUPPORTING THE OLD WAYS — Epi-genetics.

Let’s get back to the nature vs nurture discussion. Over the last 25 years the research and understanding of the nurture part of the equation has revolutionized how science now thinks of inheritance. This field is called epi-genetics.

In simplified terms, an epi-gene is a protein associated with one or more genes. These epi-gene proteins act as switches that may turn the gene on, off, or make it different. Studies in identical twins, one normal, one with major deformities, have shown the genes to be identical but the epi-genes to be vastly different.

Unlike the gene which is very stable through subsequent generations and throughout one’s life, these epi-genes are sometimes changed by environmental factors. This means that environmental influences via these epi-genes can turn genes on, off, or different.

In the last 10 years science has learned that these epi-genes can be changed by the environment as on/off/different and then inherited or passed on to subsequent generations in this new on/off/different position.

Stated more simply, environmental influences may become inherited to subsequent generations without changing the DNA blue print.

This is a completely revolutionary finding because up until now everyone thought there was no such thing as “inheritance of acquired characteristics.”

The mechanism of epi-gene inheritance is presently unknown, but probably resides in the non-DNA portion of the chromosomes. This non DNA form of inheritance has interesting implications in purebred dogs and may contribute, along with selective breeding, to the accelerated evolution in the development of the multitude of modern purebred dog in just 200 years.

Studies in humans have shown that environmental influences on a pregnant mother may be passed on through the placenta to the fetus causing inheritable epi-genic changes not just her to her offspring but also to the offspring’s subsequent generations. This concept is revolutionizing the way we think about inheritance. Certain factors of how your dog lives his/her life may be passed on to the offspring via these changed epi-genes.

Epi-genes may explain why some former great hunting dogs that became show dogs lost their hunting instincts in such a very short time of less than 50 years. The DNA/genes are still there but are “turned off” by breeding lines not focused on hunting, switching the hunting epi-genes to off. Dogs develop as their environment demands.

The implications of the old school rules which stress environmental influences in breeding hunting dogs is now supported hypothetically by science via the inherited epi-gene. Genetic inheritance now includes epi-genes as well as genes. The old ways now have at least a theoretical (certainly not proven yet) scientific justification, turn on those hunting epi-genes; “Breed the best to the best,” “If you want a good hunting dog get a pup from parents that hunt,” “To produce good hunting pups hunt the dam during pregnancy,” “Nothing makes a good hunting dog better than hunting,” “Hunting talent is a process developed over the life of the dog,” and this talent may be inherited in subsequent generations via epi-genes.

The early breeders’ rules were right. We now know the possible reasons.

For today’s hunting dog buyer and breeder looking for the best, learn about the inherited health issues in your breed and do genetic testing when applicable, pay attention to the pedigree charts, and then follow the old ways of breeding the “best to the best” when choosing or breeding your hunting dog.

 

[This article first appeared in the October, 2018 issue of Versatile Hunting Dog Magazine, and is reprinted here with permission of Drs. Salassa and Olcott and the National Versatile Hunting Dog Association. Dr. Salassa resides in Ponte Vedra, Fla., and Dr. Olcott in Frederick, Md.]

Comments (0)
If you wish to comment, please login.