Module: Understanding Genetic Clues

Learning Objectives

By the end of this module, you should be able to:

• Understand the basic principles of canine genetics that influence breeding decisions.
• Recognize the difference between single-gene and complex inherited traits.
• Use DNA testing appropriately as one component of a breeding program.
• Balance genetic health with preservation of breed type and genetic diversity.
• Apply genetic principles to make responsible, long-term breeding decisions.

Introduction

Every successful breeder develops an eye for structure, movement, temperament, and breed type. Great breeders develop something more—they understand genetics.

You do not need a degree in genetics to become a successful Bedlington Terrier breeder. However, every preservation breeder should understand how genes are inherited, how traits are passed from one generation to the next, and perhaps most importantly, what genetic testing can—and cannot—tell us.

Modern DNA testing has transformed dog breeding. Today we can identify genetic variants associated with inherited diseases, estimate breeding risks, and make more informed decisions than ever before. Yet one of the greatest mistakes modern breeders make is believing that every breeding decision can be reduced to a DNA test result.

Genetics is not about creating perfect dogs. It is about managing probability over generations.

The most successful breeders think beyond the next litter. They think about the next ten, twenty, or even fifty years. Every breeding decision shapes the future of the Bedlington Terrier.

1. Genes Are Not the Same as Dogs

One of the first lessons every breeder must learn is that a DNA test describes only a tiny portion of an individual dog.

A laboratory report is valuable information—but it is not the whole story.

A dog may be genetically “clear” for a particular mutation yet still produce affected offspring through unknown or complex genetic mechanisms. Likewise, many of the characteristics that define an exceptional Bedlington Terrier cannot be measured with a DNA test.

These include:

• Correct breed type
• Head and expression
• Balance and proportion
• Movement
• Temperament
• Longevity
• Maternal ability
• Reproductive soundness

These qualities result from the interaction of many genes rather than a single mutation.

Remember:

Genes describe pieces of the puzzle. Breeders evaluate the entire dog.

DNA testing should never replace thoughtful evaluation, pedigree analysis, or breeder experience.

Key Principle

Genetics explains risk—not destiny.

2. Understanding the Major Modes of Inheritance

Not all inherited traits behave the same way. Every breeder should understand the basic patterns of inheritance.

Autosomal Recessive

This is the inheritance pattern most breeders first learn.

A dog must inherit two copies of a recessive mutation before developing the disease.

Dogs carrying only one copy are called carriers. Carriers usually appear completely healthy but can pass the mutation to their offspring.

Copper Storage Disease has historically been considered an autosomal recessive disease associated with the COMMD1 mutation, although we now recognize the disease is considerably more complex.

The lesson:

Carriers are not “bad dogs.”

When used responsibly with appropriate mates, carriers can preserve valuable genetics while avoiding affected puppies.

Autosomal Dominant

With dominant inheritance, only one copy of a mutation may be necessary for a trait or disease to appear.

Dominant conditions often show:

• Variable severity
• Different ages of onset
• Incomplete penetrance

This means some dogs carrying the mutation may appear only mildly affected—or even appear normal for years.

The lesson:

Dominant diseases may appear to “skip generations” even when they are being inherited.

Polygenic Inheritance

Many of the traits breeders value most are controlled by dozens—or even hundreds—of genes.

Examples include:

• Breed type
• Head shape
• Topline
• Movement
• Size
• Temperament
• Longevity
• Fertility

There is currently no DNA test for these complex traits.

They improve only through careful selection over many generations.

The lesson:

Great dogs are bred—not tested.

Epigenetics: When Environment Influences Genes

Genes do not function in isolation.

Nutrition, stress, exercise, disease exposure, maternal health, and early puppy development can all influence how inherited genes are expressed.

This field of study is known as epigenetics.

A dog’s environment cannot change its DNA sequence, but it can influence how certain genes are turned on or off.

A useful way to remember this concept is:

Genetics loads the gun. Environment pulls the trigger.

Responsible breeders therefore focus not only on genetics, but also on excellent nutrition, prenatal care, puppy raising, and lifelong management.

3. Copper Storage Disease: More Than One Gene

Copper Storage Disease remains one of the defining health concerns of the Bedlington Terrier.

The discovery of the COMMD1 mutation transformed breeding by allowing breeders to dramatically reduce the number of clinically affected dogs.

However, research has continued.

Today we know copper metabolism is considerably more complex than originally believed.

Current evidence suggests disease expression may involve:

• Additional variants involving the ATP7B gene
• Modifier genes that influence disease severity
• Dietary copper intake
• Environmental influences
• Variable expression between individual dogs

This means two dogs with similar genetic test results may develop very different clinical outcomes.

For breeders, this has important implications.

• “Clear × Clear” does not guarantee lifelong liver health.
• Some dogs develop disease later in life.
• Family history remains one of the most valuable genetic tools available.

Responsible breeders think in terms of risk profiles, not guarantees.

4. CDDY/IVDD: Understanding an Emerging Genetic Risk

The discovery of the CFA12-FGF4 retrogene, commonly reported as CDDY, has added another important consideration for Bedlington Terrier breeders.

Unlike Copper Storage Disease, this genetic variant is associated with altered cartilage development and an increased risk of Hansen’s Type I Intervertebral Disc Disease (IVDD). Recent testing has confirmed that this variant is present within the Bedlington Terrier population.

Although the DNA test identifies dogs carrying the variant, it does not predict exactly which dogs will develop clinical IVDD, when disease may occur, or how severe it will become. Expression varies among individuals and is influenced by additional genetic and environmental factors.

For preservation breeders, the challenge is balancing two important goals:

• Reducing the frequency of disease-associated variants.
• Preserving the breed’s valuable genetic diversity.

As with Copper Storage Disease, responsible decisions require careful planning rather than emotional reactions or blanket elimination of breeding stock.

5. Genetic Diversity Is Genetic Health

Every breeding decision involves balancing risk.

Removing every carrier or every dog with an undesirable test result may seem like the safest approach.

In reality, it can create new problems.

Over-selection may lead to:

• Genetic bottlenecks
• Increased inbreeding
• Loss of breed type
• Reduced fertility
• Concentration of hidden recessive diseases
• Popular sire syndrome

Successful breeders strive for balance.

Best practices include:

• Using carriers strategically when appropriate.
• Avoiding affected-to-affected matings.
• Monitoring health across generations.
• Sharing information openly with other breeders.

Healthy populations require diversity.

6. Understanding Inbreeding, Linebreeding, and COI

The Coefficient of Inbreeding (COI) estimates the probability that two copies of a gene are identical because they were inherited from a common ancestor.

COI is an important tool—but it is not a measure of quality.

A low COI does not automatically produce healthy dogs.

A high COI does not automatically produce unhealthy dogs.

Instead, higher COIs increase the likelihood that recessive genes—both desirable and undesirable—will be expressed.

Thoughtful breeders use linebreeding carefully to establish consistency while planning future outcrosses to maintain diversity.

As one experienced breeder wisely noted:

Linebreeding is a tool—not a lifestyle.

7. Heritability Is Not Always Visible

Not every inherited trait can be evaluated in a puppy.

Some of the most important characteristics reveal themselves only with maturity.

These include:

• Longevity
• Temperament
• Fertility
• Structural durability
• Sound movement over time

Excellent breeders evaluate dogs throughout life—not just at eight weeks or after a championship is earned.

They also evaluate:

• Siblings
• Parents
• Grandparents
• Offspring

Pedigrees tell stories that individual dogs cannot.

8. You Are Breeding Pedigrees, Not Puppies?

Every litter influences the future of the breed.

The puppies born today become tomorrow’s:

• Stud dogs
• Brood bitches
• Performance dogs
• Therapy dogs
• Family companions

Before making a breeding decision, ask yourself:

• What will this cross contribute three generations from now?
• Will these puppies strengthen the breed?
• Will future breeders have more options—or fewer?

Great breeders think in generations.

9. Record Keeping Is One of Your Most Powerful Genetic Tools

The best breeders are also the best record keepers.

They maintain detailed information about:

• Health
• Temperament
• Fertility
• Whelping history
• Longevity
• Causes of death
• Reproductive success
• Health testing results

Equally important, they record disappointments as honestly as successes.

Open communication benefits the entire breed.

Silence delays genetic progress.

10. Testing Is a Tool—Not a Breeding Strategy

DNA testing has become an essential part of responsible breeding.

It helps breeders:

• Make informed mating decisions.
• Reduce the likelihood of inherited disease.
• Guide puppy buyers.
• Improve long-term breeding programs.

But DNA testing should never be used to:

• Replace breeder judgment.
• Eliminate valuable bloodlines unnecessarily.
• Ignore pedigree information.
• Create a false sense of security.

The most successful breeders integrate DNA testing with phenotype, pedigree analysis, health history, and decades of accumulated knowledge.

Final Thoughts: Genetics Is About Stewardship

Genetics is not about producing perfect dogs. It is about making thoughtful decisions that improve the breed while preserving its unique qualities.

Great Bedlington breeders understand that breeding is a long-term commitment built on probability, patterns, and patience. They think in generations rather than litters. They accept that no breeding decision is without risk, but they work diligently to manage those risks through science, experience, and integrity.

They value transparency over secrecy, collaboration over competition, and continuous learning over certainty. They recognize that every dog represents both a living individual and a link in the genetic chain that connects the breed’s past to its future.

In the end, genetics is not simply the study of inheritance—it is the science of preservation. Every carefully considered breeding decision helps ensure that future generations inherit Bedlington Terriers that are healthy, sound, functional, and unmistakably true to the breed.