Understanding Great Dane Genetics - The basics

It’s important for breeders to have a good working knowledge of animal genetics, regardless of the species they are breeding. Different species may have their own slang and jargon when talking about their animal of choice. Understanding both the correct scientific terms and the vernacular of a particular niche helps to have more meaningful conversations in regards to breeding stock. This article will go over genetic terminology, terms used by breeders, and genetic inheritance basics. 

Each parent animal passes half of their genetic information on to their offspring. They may pass on hereditary and genetic traits.

Traits with a genetic component are specific traits that are linked to an organism’s genetic information but may not be passed on specifically from one generation to the next. This would be things that breeders “select” for when choosing parents. In Great Danes this could be something like selecting for height, or selecting against cherry eye. These traits could pop up suddenly without warning in a litter. Diseases with a genetic component are more likely to occur in a population with a higher COI. (Read more about COI HERE). These traits may or may not be passed on and there is no way to reliably know. This is why its important for a good breeder to know their line. A good breeder will select for positive traits and against negative traits generation after generation.

Examples of traits with a genetic component in Great Danes: Height, lip, ectropion, entropion, cherry eye, weight, front assembly, rear assembly, top line, chest, head set, intelligence, personality, confidence, trainability, bloat, hip dysplasia 

Other traits are hereditary. Hereditary traits are linked to a specific combination of genes. These traits behave in a very specific way and will pass predictably from generation to generation. This can be extremely helpful in selecting breeding pairs as you will know what traits the offspring will have. 

Examples of hereditary traits in Great Danes: Color, Addison's disease(speculated current research being conducted by UC Davis 2024), Inherited Myopathy 

There are four main terms used to describe the expression of specific hereditary traits: 

Recessive - Needs two copies of a specific gene/s to be visible. 

Dominant - Needs one copy of a specific gene/s to be visible

Incomplete Dominant - A single copy of the gene will have one impact and two copies will have a different impact

Allelic - traits on the same gene that have a dominance hierarchy or may interact with each other in a codominant/incomplete dominant way

The traits that an organism has is called its genotype. The traits that an organism expresses or shows are called the phenotype.

Possessing one copy of a specific train is considered to be a heterozygous. Depending on the niche you are in this could be referred to as being “het” for the trait or a “carrier” if the specific trait in question is recessive, or if it relies on another gene to be expressed phenotypically. A heterozygous animal could pass on either trait to each offspring.  

Two copies of a specific trait would be called homozygous. An animal that is homozygous for a specific trait can only pass on that specific trait to its offspring. All offspring will have at least one copy of the trait because thats all the one parent was able to pass on. 

Other helpful terms:

Allele - ​​The version of a gene that is present. Each organism has two alleles per gene. 

One inherited from each parent. 

Polygenic - A trait that is influenced by two or more genes that work together to 

produce a specific outcome. 

Locus - The specific position of a particular gene within the genome.

Genome - The specific genetic information that an organism possesses. 

Knowing the genetic information of each parent can help you predict and control what colors puppies are in a litter. At Wanderlust Danes we price our puppies according to their color genetics. If a particular color all of the sudden became very popular we understand that we could produce entire litters with just that color (with two exceptions. Read more about individual colors HERE). We do of course always prioritize health, temperament, and structure over color. The color genetics is just one of the many factors we take into consideration when breeding. 

Below are some examples of Punnett Squares which are used to predict specific outcomes. For simplicity Moms will be listed on top in pink, and dads will be to the left in blue. It doesn't matter which dog is placed where on the square graph. We will be using two recessive traits below to show a few sample predictions. Chocolate, and dilute are both recessive traits. We will use the accepted Bb combination for the TYPR1 gene which dictates if a dog will be black or brown (In danes called chocolate) and Dd for MLPH gene which dictates if a dog will be full color or dilute (In danes called Blue and Lilac)

Example 1

In this example mom is Black and carries chocolate

Dad is chocolate 

The chance of each puppy being chocolate or black is 1:1 

Keep in mind that each puppy is its own coin toss of luck so while the odds are 1:1 you could end up with all puppies being one color or another. 

All puppies will either carry or show chocolate because dad can only give chocolate alleles

Example 2

In this Example mom is dilute black (called blue in danes)

Dad is black and does not carry anything 

Black is dominant over dilute/blue so all of these puppies will be black, and they will all carry blue since both parents are homozygous. All puppies will heterozygous.

Example 3

In this example Mom and Dad are both chocolate. This one is super easy but the only thing the puppies could possibly be is chocolate. So we can guarantee colors even if they are recessive.

Example 4

In this example both mom and dad are black and carry chocolate. This particular combination is what initially started the practice of breeding color pure. (read more about color pure breeding and why we don't do it HERE) Chocolate is not a showable color but it can potentially and unexpectedly pop up in lines that are not genetically color tested. In this example puppies have a 1:4 chance of being chocolate and a 3:4 chance of of being black. Of the black puppies 2:3 odds that each puppy carries chocolate.

So what happens when looking at multiple traits? The graph just gets bigger. On top we still have moms in pink and to the left dads in blue. We list each possible allele combination that mom and dad could potentially give. This could be done with as many traits as needed.

Example 5

In this example mom is a lilac meaning she is homozygous for both chocolate and dilute. Even though she can only give bd combination we would still carry that out across four squares so that each allele is correctly represented. Dad is a Black dog that carries both the chocolate and dilute gene. Keep in mind this could be stated as Dad carries blue, lilac, and chocolate as he genotypically carries all the genes needed for each of the listed colors. Some breeders may state that dad is black and carries lilac, or dad is black and carries blue and chocolate. These are not incorrect to say but for someone who does not understand genetics this could lead to some confusion when puppies are born lilac, chocolate, and blue.

Example 6

In this example mom is blue and carries chocolate/lilac and dad is chocolate and carries blue/lilac. With this combination lots of colors are possible.

Understanding genetics allows for us to accomplish our breeding goals of breeding more genetically diverse lines by creating carriers of a desired uncommon color. It also gives us more flexibility to chose a dog that has amazing structure but perhaps only carries a color that we were hoping for. It also ensures that we do not breed dogs with avoidable defects. Inherited Myopathy for example is a recessive trait. So if we were to find out that one of our perfectly healthy dogs was a carrier for this disease we could still keep them in our breeding program as long as we only breed to dogs who are not carrieres.