March 16, 2022  PRELIMINARY SUMMARY (click for full article)

The Greater Swiss Mountain Dog recently received the preliminary analysis of their breed’s genetic diversity by submitting 34 unrelated Greater Swiss Mountain Dog to UC Davis for analysis. As a result, Dr Felipe Avila has created the initial report. Click here to request GSMDCA to add your Greater Swiss Mountain Dog to the population in our database!

 

What having more or less genetic diversity means to a breed

After 6 years of carefully analyzing levels of genetic variation and inbreeding in 46 different purebred dog breeds, as well as their health concerns and breeding success, we can see some general trends, trends which are well supported in the large body of scientific literature regarding closed populations and genetic diversity. How healthy and functional a modern purebred dog breed is depends on several factors:

• the number of founders

• the health of those founders

• the historical events or conditions that may have affected the breed

• breeder culture and habits in breeding

By and large, breeds with more diversity tend to be healthier. If a breed’s founders were quite healthy, the breed can remain relatively healthy despite having little diversity if that diversity is not further depleted. Even breeds with a great deal of variation can be largely unhealthy if most of the breed is highly inbred and owe most of their ancestry to unhealthy founders. The healthier breeds tend to have well distributed diversity, meaning each family is genetically different from one another. When a breed is essentially a single family, which is sometimes the case, they are healthier when as outbred as possible.

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How inbred is the typical Greater Swiss Mountain Dog?

First off, let’s talk a little about what the researchers at UC Davis are looking at in the report. One aspect of the UC Davis canine genetic diversity test is a calculation called “internal relatedness” that estimates how inbred a dog is. It is widely used by conservation geneticists all over the world. Internal Relatedness, or IR, is a number between -1 and 1. When a dog is more inbred, the number will between 0 and 1; the closer to 1 the more inbred the dog. When a dog is more outbred, the number will be between -1 and 0; the more negative the number the more outbred the dog.

An outbred puppy has inherited markers from its sire that are very different from those it inherited from its dam, so the parents of this puppy are most likely unrelated, or genetically dissimilar. An inbred puppy inherits many of exact same markers from both dam and sire, so the parents of this puppy are most likely closely related to one another, or genetically similar. Being outbred reduces the likelihood of known and unknown recessive genetic diseases being expressed in individual dogs. It also reduces the chances that a complex disease with a recessive component will rear its ugly head. When dogs in a breed are, on average, more outbred, the natural healthy genetic variation in the breed is more easily preserved. When dogs in a breed are, on average, more inbred, the natural healthy genetic variation in the breed is more quickly lost, or bred out inadvertently through a process called genetic drift. All preservation breeders should do their best to reduce genetic drift in their breeds through careful choices of breeding pairs. This loss of existing genetic diversity of a breed, or biodiversity (described simply below), is necessary to maintain their breeds for the future.

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Click here for the full article.