Diversity of Dog Breeds

Why the Health of the Parents Alone Is Not Enough and Why the Future of Breeds Depends on Genetic Diversity

Every mating affects the future of the breed.
Not only the health of one litter, but also the genetic stability of future generations.

Introduction: A Problem That Is Not Visible at First Sight

Today, many breeders responsibly test for hereditary diseases and monitor conformation, working abilities, and temperament. Nevertheless, in many breeds there has been a long-term increase in:

• allergies,

• autoimmune diseases,

• fertility problems,

• lower vitality,

• shorter lifespan,

• reduced working performance.

The reason often does not lie in one specific disease. The problem is usually deeper → a gradual loss of the breed’s genetic diversity.

Over the past several decades, the gene pool of many breeds has narrowed significantly, often unintentionally due to:

• excessive use of popular champions,

• selection focused only on appearance,

• excluding too many individuals from breeding,

• overly narrow focus on certain genetic tests,

• repeated use of the same bloodlines.

Genetic diversity acts as a “safety net” for the population. The more diverse the population is, the better it can cope with:

• hereditary burdens,

• polygenic diseases,

• environmental changes,

• long-term health problems.

Every Breeder Influences the Future of the Breed

Breeding is not just a decision about one litter.

Every stud dog and every bitch influence:

• the future genetic composition of the breed,

• the level of relatedness within the population,

• the future breeding options for other breeders.

Genetics is not merely an individual issue concerning one dog. It is a collective responsibility of the entire breeding community.

Why Disease Testing Alone Is Not Enough

Genetic tests are extremely important. They help:

• prevent serious hereditary diseases,

• identify carriers,

• plan safe matings.

However, if breeding focuses only on “eliminating everything risky,” the opposite problem may arise.

A Simple Example

Imagine a breed with 1,000 dogs.

If we decide to exclude all carriers of a certain recessive mutation from breeding, suddenly only 300–400 “genetically clear” individuals may remain.

The result?

• the gene pool narrows significantly,

• relatedness increases,

• the risk of other problems rises,

• diversity drops sharply.

That is why modern genetics recommends:

• not automatically excluding carriers,

• using genetic tests wisely,

• combining them with evaluations of population diversity.

A carrier does not pose a problem for healthy offspring if paired correctly with a genetically suitable partner.

What Genetic Diversity Means

Genetic diversity describes how genetically varied the population of a breed is.

The greater the diversity:

• the lower the relatedness,

• the greater the genetic stability,

• the lower the risk of accumulating problems.

Conversely, low diversity means that dogs within the breed are becoming genetically too similar.

Why Monitoring COI Alone Is Not Enough

What Is COI?

COI (Coefficient of Inbreeding) expresses the probability that offspring will inherit identical gene variants from both parents due to their relatedness.

Simply put:

• low COI = the parents are not closely related,

• high COI = the parents share common ancestors.

Important: Low COI Does Not Automatically Mean High Diversity

This is a very common misunderstanding.

Two dogs may have:

• a low COI,

• yet still come from a genetically very similar population.

A pedigree does not show the actual genetic similarity across the entire DNA.

In addition:

• pedigrees are limited by the number of recorded generations,

• they do not capture hidden relatedness,

• they do not reflect the real distribution of genes within the population.

That is why genomic methods based on SNP DNA profiles are becoming increasingly important today.

What Is an SNP DNA Profile?

An SNP profile analyzes hundreds of genetic markers across the dog’s entire genome.

This makes it possible to determine much more accurately:

• genetic similarity between dogs,

• population diversity,

• heterozygosity,

• actual genetic distances.

This is exactly the type of data used by the application:

diverzita2020.genomia.cz

How the PCA Diagram Works

What Is PCA?

PCA (Principal Component Analysis) is a mathematical method that transforms a huge amount of genetic data into a clear and understandable graph.

Simply explained:

• every dog has hundreds of genetic data points,

• PCA “compresses” them into a simple similarity map.

How to Read a PCA Diagram

Basic Principle

• each point represents one dog,

• points close together are genetically more similar,

• points farther apart are genetically more different.

This is not about “better” or “worse” dogs.

The diagram only shows:

• how genetically similar individuals are,

• the structure of the breed population.

Why PCA Is Useful for Breeding

PCA makes it possible to view the population as a whole.

This allows breeders to:

• better understand breed diversity,

• identify less-related bloodlines,

• avoid repeatedly using the same genetic directions,

• plan matings with greater genetic variation.

How to Select a Suitable Breeding Pair

The ideal mating is not:

• simply the most beautiful dog,

• only the most successful show champion,

• nor merely the genetically “cleanest” individual.

Responsible selection combines:

• health,

• temperament,

• conformation,

• working abilities,

• genetic testing,

• population diversity.

In Practice Within the PCA Diagram

It is often advisable:

• not to choose a dog located directly in the center of the same cluster,

• but also not to select an extremely distant individual without understanding the bloodline.

The goal is:

• to reasonably broaden diversity,

• without deepening genetic uniformity.

Heterozygosity – Why It Matters

What Does Heterozygosity Mean?

Heterozygosity expresses how genetically varied an individual dog is.

Higher heterozygosity generally means:

• greater genetic variability,

• better biological resilience,

• lower probability of certain inbreeding-related problems.

Lower heterozygosity may be associated with:

• close relatedness,

• a long-term closed gene pool,

• repeated use of the same bloodlines.

What the Application Displays

The application diverzita2020.genomia.cz by Genomia displays:

• the breed PCA map,

• the position of a specific individual,

• the individual’s heterozygosity,

• heterozygosity distribution across the whole population,

• breeds with databases containing 30+ DNA profiles.

This allows breeders to see:

• how their dog compares within the breed,

• whether it comes from an overrepresented bloodline,

• or whether it represents valuable genetic enrichment.

The Risk of Popular Stud Dogs

One of the biggest problems in modern breeding is the excessive use of a single male.

Even an excellent dog, if overused, can:

• dramatically reduce population diversity,

• increase relatedness in future generations.

A Typical Scenario

• an exceptionally successful champion appears,

• he is used very intensively,

• within a few years he produces a huge number of offspring,

• in the next generation, dogs become significantly more related.

In the short term, this may not be obvious.
In the long term, however, diversity declines sharply.

Imports Are Not an Automatic Solution

Importing a dog from abroad can significantly enrich diversity.

However, if:

• the imported dog is used too frequently, a large number of half-siblings are created,

• in the next generation, population relatedness begins to increase again.

That is why it is important to:

• distribute the use of stud dogs reasonably,

• work with a larger number of bloodlines,

• monitor the population as a whole.

Diversity and Polygenic Diseases

Many modern health problems such as:

• allergies,

• autoimmune diseases,

• certain orthopedic disorders,

• immune system disorders,

are not caused by a single gene.

They result from a combination of:

• multiple genes,

• environmental influences,

• long-term loss of genetic variability.

Genetic diversity helps populations better resist these complex problems.

Small Breeds and Small Populations – A Specific Situation

In small populations, working with diversity is even more important.

Often:

• there are very few unrelated bloodlines,

• one dog may influence a large portion of the population,

• relatedness increases rapidly.

Therefore, it is advisable to:

• monitor diversity across the whole population,

• limit excessive use of individual dogs,

• cooperate among breeders,

• use genetic data when planning matings.

Modern Genetics Helps Make Better Decisions

In the past, breeders mainly relied on:

• pedigrees,

• experience,

• knowledge of bloodlines.

Today, SNP DNA profiles make it possible to work much more precisely.

Genetic data allow breeders to:

• better understand the population,

• protect diversity,

• plan more sustainable breeding programs.

The Future of Breeds Depends on the Decisions of Today’s Breeders

Responsible breeding is not about searching for the “perfect dog.”

It is about:

• long-term thinking,

• working with the population,

• protecting genetic diversity,

• balancing health, breed type, and diversity.

Every SNP profile provides additional information about the breed population. And the more data available, the better diversity can be evaluated and protected.

Discover the Diversity of Your Breed

Using SNP DNA profiles from Genomia, you can:

• display your dog within the breed PCA diagram,

• monitor genetic similarity within populations,

• evaluate heterozygosity,

• work with diversity when planning breeding.