How Does Genetics Influence a Dog's Health and Behavior?

Recently, Emily Anthes from the New York Times reported that the genetic influences on dogs' health and behavior based on their breed. For a long time, through selective breeding, humans have been responsible for handcrafting the characteristics that give dachshunds their short legs, Great Danes their immense size, and pugs flat faces. Breeders face the challenge of distinguishing dogs to make them unique but are limited to a few genes. Choosing and inbreeding dogs with recognizable characteristics makes them susceptible to mutations due to exaggerating their attributes to increase rarity. For example, the gene that codes for dog size is insulin-like growth factor-1, which varies in small and large breeds; similarly, only three genes are responsible for a dog’s coat type. A dog’s breed is directly related to its health; since most breeds are homogeneous, they are susceptible to the same diseases, like degenerative eye disease, which is common in Labrador retrievers.

On the other hand, mutts and mixed-breed dogs may have a lesser chance of contracting some of these diseases, but due to how highly inbred they are, they are likely not much less vulnerable. Aside from the hazy connection between dog breeds and health, the connection between dog breeds and behavior is even more unclear. Due to humans prioritizing appearance over behavior when breeding dogs, the main distinction in breeds is how the dogs look, more so than how they behave. While some dogs lean towards one behavior over another, like a terrier, which is more predacious than a border collie, behavior alone is not enough to distinguish the dog breed. Conclusively, only 80% of dogs in the world live free and unconfined from humans, a small percentage of which are purebred or have no known ancestry.

I believe dog breeders wield too much authority over the lives of these powerless animals. Dogs should not have to suffer from inefficient characteristics like a pug's flat face because it'll make the breeder more money. Generally, dog breeders don't consider the genetic factors regarding health or behavior that significantly affect the dog's ability to find a loving home after being bred. This careless act turns dogs from loving beings needing love and care into commodities sold without regard.

Is Dog Breeding Just Puppy Eugenics?

 

Eugenics is defined as the selective breeding of humans to “improve” the population by increasing heritable traits that are deemed desirable. Although eugenics is a particular example of selective breeding, as well as breeding of dogs, eugenics is a concept applied to the human population only. The question of whether or not selective breeding is morally wrong has been a question brought forward in many various examples, but what about one of the most normalized examples: dog breeding.

The arguments made regarding dog breeding pertain to the ethical concerns of genetically favoring traits for the human benefit. Edwin Louis-Maerten argued that although selective dog breeding and humanistic eugenics have similar compasses, that does not make the mere practice of dog breeding itself unethical. It is argued that the practice itself is just morally questionable, but multiple perspectives are necessary to understand why people breed dogs and whether or not the choices are more harmful than good. 

Personally, I do not fully understand the desire of breeding dogs. I believe a true pet parent would love any animal by any means necessary, but I can understand favoring a specific kind of dog for the purposes of service. For example, a larger dog as a guide dog for someone who cannot see well/is blind. But I do not see the point in breeding a completely new dog for this need. 

Article: https://www.frontiersin.org/journals/animal-science/articles/10.3389/fanim.2023.1195710/full 

Other Source: https://www.tvmf.org/articles/responsible-dog-breeding/#:~:text=The%20primary%20reason%20to%20breed,puppy%20related%20to%20a%20dog. 

Genetics and Dog Breeds

     

    Humans have placed artificial selective pressures on dogs for centuries. People have bred them for their temperament, size, and other physical features. These selections have made the dog breeds we know today. I chose an article written by Jill Adams that was published in Nature in 2008. The article highlights a variety of studies performed by researchers about the genetic factors involved in dog breeding. 

    Adams delves into the possible deleterious effects of dog breeding for specific physical characteristics. I found this to be particularly interesting because many brachycephalic dog breeds experience difficulties breathing. While the breathing difficulty is not a deleterious genetic defect, Adams mentions that some of the effects may not be known and that some have affected the mitochondrial genome in many dog breeds. 

In Dog DNA, Small Size Has an Ancient Pedigree

 

A group of researchers collaborated together to come up with DNA charts.  They came to the conclusion that smaller dog breeds seem to be ancestral to larger canines. In fact, there is no specific gene that determines a dog's size whatsoever, but there are 25 genes that can determine their unique size. It is called a single "IGF1 Allele". A single IGF1 single-nucleotide polymorphism haplotype is common amongst all small breeds, and it is nearly absent in larger canines. In the article, it states, "This little bit of DNA isn't a gene, as a result of by definition a gene has to comprise the directions to make a protein. However, many different stretches of DNA have the directions for bits of RNA that assists to manage genes. He discovered a DNA have the directions for bits of RNA that assist to manage genes. He discovered a DNA stretch that has directions for what is known as anti-sense RNA, which performs a major function in controlling the manufacturing of proteins specified by genesis discover known as IGF1-AS and it is available in 2 variants. 

Most Dog Breeds Highly Inbred

 

    It seems as if there are more dogs who are showing up with health problems to the veterinary. Many individuals have also seen the trend of dogs health diminishing. Fortunately scientists have seen the concern and have done some studies on a dogs health. 

A recent study has shown DNA samples from nearly 50,000 dogs of over 200 different breeds. The study has found on average dogs have showed about 25% inbreeding. That is the equivalent of your parents being brother and sister or parent and child. The study involves data from pet insurance and dog genetics companies. Pet insurance and dog genetics companies were used in the study to compare a dog's health and the death rate of different dog breeds. The pet insurance data was used from Sweden. 

    The study wanted to compare more than just inbreeding, the study also measured the "identify a relationship between body size, body morphology, inbreeding and health in dogs." (Bannasch et al. 2021). Overall the study was very informative as to the health of dogs breeds. Showing inbreeding can cause some kind of health problem for a dog was very interesting to read. For another article similar to this one, please click here. 

Genetic Diversity in Dogs to Save a Breed

Eleanor Cummins in To Save a Dog Breed, Change It has found that a rare breed out of Norway called Norwegian Lundehund which was used for hunting puffins, had six toes to be able to grasp rocks and mountains but was also able to bend its neck backwards to fit into small caves. In the 1960s there were only five dogs left due to them catching canine distemper, which is fatal.Since so many Norwegians thought of the dog as a national symbol they built the population to a few hundred but it was done by inbreeding. 87% of the genes of the dogs came from the same genetic pool, so many of these dogs had health issues such as stomach cancer and skin conditions. To increase their genetic diversity, breeders had begun breeding with similar dogs that produce ones that look like the Lundehunds. Cummins has a one year old mix of a Lundehund and a Norwegian buhund, but the puppy is still too young to see if he will have the issues like a Lundehund. Many purebred enthusiasts do not agree with intermixing the breeds, but the distinct traits of the Lundehund are still produced.

Inbreeding causes so many issues for dogs and it is usually due to humans getting involved to keep the breed around. I agree that intermixing was the correct thing to do, even though it is no longer a purebred, the dogs have similar qualities and will live a healthier and happier life.  The intermixing will keep the people who want Lundehunds happy but also produce healthier dogs.

Breathtaking gene discovery in Dalmatian dogs

A new genetic study conducted by the University of Helsinki has uncovered a gene associated with acute respiratory disease syndrome (ARDS) in dogs specifically dalmatians. Acute respiratory disease syndrome (ARDS) is a condition of sudden respiratory failure due to fluid accumulation, and severe inflammation in the lungs.To diagnose acute respiratory disease most veterinarians will use  the method of  blood gas analysis that measures the levels of oxygen and carbon dioxide in the blood to determine how well the lungs are functioning.  In humans there are many causes for lethal respiratory distress such as pneumonia. In dogs the cause is a genetic disorder resulting from a defect in anillin protein which binds to actin, this protein is important in cell division and growth. Lack of anillin can lead to malformed epithelial structures thus inhaled air, will become trapped in the alveolar walls. The mortality rate in dogs that have ARDS is 100 percent if left untreated.Despite advances ARDS still remains one of the most difficult disease to treat. This gene discovery provides new insights into the mechanism of lung injuries that can lead to recovery or complete eradicate it from certain breeds. 

https://www.sciencedaily.com/releases/2017/03/170314092756.htm

http://www.mydogdna.com/

Man's Long Lasting Friend

Dogs in the modern day and age have been called man's best friend, but many forget that they have been our friends the longest out of all bred and domesticated animals throughout the history of the human race. A grad student from the United Kingdom, Angela Perri, has been trying to identify how dogs may have been used in the hunting techniques of early human civilization. While accompanying hunters near Hiroshima, Japan, she observed how dogs were used to hunt. Through warning the hunters when the boars were close, they protected the hunters from a blindsided boar charge and shed off time during the hunt with their senses Perri then began studying the companionship and found history of 110 dog burials in Japan.

Artwork of an Ancient Japanese Hunt with Dogs

The fact that the Japanese dogs were only revered in a time and place where they would have made ideal hunting companions strongly suggests that they did indeed play this role, Perri reports this week in Antiquity. She also points to a 2500-year-old bronze bell found on the cast coast of Honshy that contains an engraving believed to depict an event from even further in the past: a boar surrounded by a hunter and his pack of dogs.

Now she, along with other scientists are looking for evidence in dog evolution over time to see how they have been domesticated to be hunting companions. In the light of genetics, one would be able to look at the fossils left behind to see certain changes in gene expression over time of the structural changes that dogs went through during their domestication over thousands of years. This question along with what truly tamed the dogs still remains uncertain today.

Some think early human hunter-gathers actively tamed and bred wolves. Others say wolves domesticated themselves, by scavenging the carcasses left by human hunters, or loitering around campfires, growing tamer with each generation until they became permanent companions.

The importance of this discovery surpasses the idea that dogs are now our friends. It is important to identify the first human and dog relationships in order to fill in the gaps in our human history and development. Our manipulation of breeding and genetics of other animals could have affected our own evolution and development and how we grew and changed as human beings.

Regardless of the missing evidence that we have in modern time, I think that it is rational to believe that humans, in order to hunt better, domesticated dogs and bred them selectively to these capabilities. Having evidence such as a systematic dog burial obviously means that dogs were very important for humans to breed and befriend. Whether they were used for nursing, hunting, protection, or friendship, the dog was the first and one of the most important domestic animals to develop our human civilization and promote our survival.