Just like in humans, DNA (Deoxyribonucleic Acid) is the dog's genetic 'blueprint'. It is a long thread-like molecule which carries the ‘genetic code’ that determines the dog’s individual characteristics. DNA is found in almost all of the dog’s billions of cells. Every puppy inherits a unique mixture of DNA from its parents so, except for identical twins, no two dogs in the world have exactly the same genetic code.
DNA Profiling works by detecting certain parts, or 'markers' in the DNA molecule that are known to vary greatly between unrelated dogs. Our tests compare the DNA at a number of these markers to provide a powerful identification test. The laboratory process to produce a DNA profile is called Short Tandem Repeat (STR) profiling. STR profiling is a very sensitive DNA testing procedure that was originally developed for forensic analysis in humans.
A sample of the dog’s cheek cells (also known as buccal cells) is collected with a simple swab and transferred to a special collection card, which protects the DNA sample so that it can be easily transported to the laboratory - in this form the DNA sample can also be stored safely for many years. At the laboratory, DNA is extracted from the sample and a special enzyme is used to copy the genetic code at the relevant regions in the DNA. At Cellmark the dog DNA profile is comprised of 18 DNA markers (plus one which is used to confirm the sex or gender of the dog) that are known to be highly variable between individual dogs. This analysis results in a graph with coloured peaks representing each of the targeted STR markers (usually two peaks per marker, one inherited from the mother and one from the father). As part of the analysis the genetic size of the DNA markers are measured which allows the dog’s DNA profile to be digitally recorded.
This type of DNA profiling allows the dog to be individually identified from other dogs, including its parents and siblings. Because a dog’s DNA markers are inherited from his or her parents, the DNA profile can also be compared with the dog’s sire and dam to confirm parentage. These markers are chosen specifically to provide a highly discriminating identification test – they do not highlight any possible genetic abnormalities or traits and does not give an indication of the breed of the dog.
The dog’s DNA profile can then be stored on a database which means that it can be compared against the profile of any dog that might be found or recovered following loss or theft in order to reunite the dog with its owner.