The English Cocker Spaniel is a small-sized gun dog that is mainly used for hunting, dog sports and dog shows. The breed is divided into show and working lines that have distinct characteristics. In this article, we focus on English Cocker Spaniel breed data created by the MyDogDNA testing panel, focusing especially on genetic diversity.
Genetic diversity lower than the all-breed average
Genetic diversity of English Cocker Spaniels is lower than the all-breed average with the median of 30.2% (picture 1). This is most probably due to the breed’s developmental history where spaniel breeds were divided into smaller categories, separating working and show lines and inbreeding in the course of the breed’s history. Genetic diversity of the Cocker Spaniel related breeds is also below average. The Cavalier King Charles Spaniel has a particularly alarming median genetic diversity level of only 25.2%. For comparison, mixed breed dogs have a genetic diversity median of 43.3%.
Picture 1. Genetic diversity in English Cocker Spaniels.
Maintaining and even improving genetic diversity is important for every breed. It is particularly important for breeds in which the genetic diversity level is already low. Low genetic diversity predisposes the dog to recessively inherited hereditary disorders by increasing the risk for inheriting the same recessive disease mutation from both of its parents. Low genetic diversity also increases the risk for autoimmune disorders and predisposes to inbreeding depression.
The MyDogDNA Breeder Tool has been developed to help in finding the genetically most different dogs for breeding partners. This helps the breeders in maintaining genetic diversity within their breed. The Breeder Tool takes into account also the hereditary diseases tested by this panel. With this tool, it is not only possible to maintain genetic diversity, it enables also preventing hereditary disorders. You can find the tested hereditary disorders encountered in English Cocker Spaniels on the Breeds page.
Show and working lines are genetically very different
Picture 2 shows genetic differences between show and working lines of English Cocker Spaniels. One dot represents one tested dog. The closer the dots are to another, the closer these dogs genetically are to each other. Dogs are coloured by a certain colour after the owner has added a tag in the dog’s profile telling the main use of the dog. You can find this graph as a three-dimensional model on the Breeds page.
This graph shows that hunting line English Cocker Spaniels (blue dots) are genetically quite different from the show line (yellow and orange dots). We also see distinct genetic differences inside the show line. By studying this graph, we noticed that parti-coloured English Cocker Spaniels were at one end of the show line’s graph and solid coloured dogs were in the other end.
Knowing all this, it is not a surprise that the English Cocker Spaniels with the highest Genetic Health Index are the dogs that are crosses between show and working lines. Also the best genetic matches for show line dogs in the MyDogDNA Breeder Tool are working line dogs and vice versa. The expected genetic health index for these line crosses is high, much different than when breeding strictly inside one line.
Picture 2. Genetic differences between show and working lines.
Populations differ between countries
Picture 3 demonstrates the genetic relationships of English Cocker Spaniels born in different countries. One dot represents one tested dog. The closer the dots are to another, the closer these dogs genetically are to each other. You can find also this graph as a three-dimensional model on the Breeds page.
This picture shows that the US population of English Cocker Spaniels is partly different from the population in Europe genetically speaking. It would be interesting to see more country-level populations on this graph, and to see how the working and colour lines segregate in other countries. This graph can be used for instance when planning imports to find dogs that would bring as different genetic material as possible into the country’s existing population
Picture 3. Genetic relationships of the English Cocker Spaniels tested with the MyDogDNA panel.
When putting together all this information about genetic diversity, breed lines and country populations in the English Cocker Spaniel, it is easy to see that although the genetic diversity of the breed is alarming, the breed is in a good situation for improving genetic diversity. Country populations and show and working lines are genetically very different and new genetic material can be found within the breed.