Unveiling the Mystery: Exactly How Animal DNA Tests Work

Dog breeds are very different from one another, a fact that becomes even more obvious when you visit any dog show: compare an Irish Wolfhound and a Chihuahua, for example. Breed traits are hereditary, so it should be possible to detect them at the DNA level. This is exactly what some laboratories are doing, but how exactly do they do it? We're about to tell you.

What are Genetic Variants

As we mentioned earlier, the DNA in all animals of the same species (such as dogs) is generally very similar, but there are differences. These differences are called genetic variants and occur in different combinations in different dogs. Some variants may relate to a dog's external traits, while some variants have no effect on the formation of the animal and are only detected by DNA analysis.

The genetic variants found in dogs are registered in special databases, which currently have more than 43 million records! Each dog contains thousands of these variants, which are used, among other things, for genetic identification of animals and parentage, which boils down to finding unique combinations of genetic variants in parents and tracing these variants in offspring.

Genetic Variants in Breeds

Breed testing in general terms is a similar task - finding a set of genetic variants that are present in all dogs of one breed and absent in other breeds. It is important to realize that a variant may be present in many breeds or in several related breeds. Here are a few examples:

• The same mutations associated with the formation of colors are found in many breeds. For example, the at mutation in the locus A is associated with the formation of Chopra color. The situation is similar to other mutations in colors;

• The same variant is associated with short-leggedness in many breeds - in dachshunds, corgis, bassets, and others. This trait occurs in dogs with an extra copy of the FGF4 gene on chromosome 18.

Obviously, such variants cannot be determinative of breed specificity.

A good example is that most breed-specific variants are extremely rare and occur within breeds in some dogs. For example, Alaskan Malamutes carry a mutation (c.293G>T) in the NDRG1 gene, which results in polyneuropathy. This malamute-specific mutation has only a frequency of 10-12%. Thus, even this kind of variant also could not fully explain a breed.

How to Determine Breed Identity?

So, to conduct a breed test, you need to find a more or less compact list of genetic variants that are found in the vast majority of dogs of that breed and not in other breeds. When you order a pet DNA test, you send DNA samples to a lab that does just that, based on such a list. This is a very non-trivial task because even within a breed there is considerable genetic diversity. Therefore, breed identification tests take a slightly different approach.

Basepaws, the company that conducts these tests, has the technology at its disposal to analyze a large number of genetic variants for each dog - thousands or even hundreds of thousands at a time. Each dog's result is compared to a database containing results for dogs of different breeds. A computer analysis of multiple genetic variants identifies the group of dogs in the database that the dog being tested most closely resembles. If the similarity is high, it is concluded that the dog has a high probability of belonging to a particular breed.

The Accuracy of These Tests

The result of the test is a number that characterizes the closeness of the tested dog to one or another breed. More sophisticated computer algorithms can suggest the probable origin of mestizos from two or more breeds.

Each dog's result is compared to a database containing results for dogs of different breeds. A computer analysis of multiple genetic variants identifies the group of dogs in the database that the dog being tested most closely resembles. If the similarity is high, it is concluded that the dog is highly likely to belong to a particular breed.

Similarity in this case is defined as the consistent coincidence of a significant proportion of genetic variants with variants found in dogs of the same breed. However, slightly different combinations may coincide in different dogs within a breed. But ultimately the accuracy of such tests can be described as high.

What Are the Scientific Benefits of DNA Tests?

Animal DNA testing is much like a similar test for humans, which assesses a person's probable ancestry and can even locate relatives if they have also taken the test. Such tests and the compilation of detailed databases are of interest in terms of studying genetic diversity within breeds and are an important step towards so-called genomic selection, which is already being used in the breeding of farm animals.