Why did my dog’s DNA test show unexpected results?
There are a few ways you can get unexpected results. One is that the dogs in the database do not include enough range of the breed to accurately get percentages. There is no gene jumping up and down saying “McNab” or “Border Collie”. They are comparing your results against sample results. If the samples are too limited, they will be looking at the next closest matches. Trying to decide which breed and how much it is a judgement call. I like to describe it as trying to decide when on a color gradient does blue change to green.
Second is that McNab’s are mostly appreciated by ranchers trying to get a job done. “Purebred” is not as highly valued as talent, and to be honest, sometimes convenience or circumstance. Another breed may bring to the table qualities that are not strong in the McNab – and vice versa. Also, as livestock experts, ranchers are more than a little familiar with the risks of close breeding and will normally outcross their livestock for genetic health. So why would they not do so for their dogs? A closed registry – one which permits only dogs reaching back to a few founders – can be achieved only at some genetic cost.
Third, well, accidents happen, mistakes get made, memories are fallible, and people are people. We cannot rule out that what we thought we had might not be what we do have. Before we let our blood pressure rise on that possibility, it is of value to look at whether the dog in front of us meets our expectations. If further investigation is appropriate this would be a time for parentage testing rather than breed identification. Parentage testing is at its best in ruling out a parent. It is a long-established test that is not dependent on other breed records.
What anyone using McNab’s for real ranch work wants is that when they buy a puppy that the dog will be able to do the work that they need. To that end there is now an effort to be more direct in preserving those qualities. A McNab does not work like a BC, and mostly BCs cannot do the kind of livestock work asked of McNab’s. So, while someone might add a touch of BC for genetic health, or some specific quality, the breeding goes back to the McNab qualities, just as it does for breeds of livestock.
DNA is a valuable tool even if it is not 100% perfect at identifying breed. The significant part is the ability to identify relationships. Tracking the qualities of the dogs – whether physical qualities, temperament, behavior or working qualities – and having the DNA – allows better tracing of that which preserves those qualities. DNA testing can help us identify true heritage if records have become confused. Identifying relationships helps us keep the diversity in the lines that is critical to genetic health.
Using a registry is good for the genetic health and long-term predictable qualities of the dog. It will help develop the balance of genetic diversity (because it is easier to avoid close family lines), genetic health (because health issues can be recorded and traced even if they appear well beyond breeding age) and predictability (because it fosters tracking the actual qualities of the dog). Contributions of non-reproducing dogs also strengthen the database information. These dogs still have their qualities, and their DNA, and their heritage strands that help us evaluate how well the entire line meets the overall goals.