A mixed-breed dog whose ancestors are purebred generally is easier to identify than a dog descended from many generations of mixed breeding. Typically, breeds have distinctive genetic markings due to the fact that their members are genetic isolates — that is, bred from a limited population of dogs. The more distinct & unique the breed characteristics are, the easier it is to identify a breed’s members by the DNA method.
The markers used by researchers are not actually genes themselves, but really they are recurring series of DNA known as microsatellites. The commercial tests use a different kind of marker known as single-nucleotide polymorphisms — also known as SNP’s— that are small mutations within the genome. Whether using microsatellites or SNPs, the markers, taken together, combine to form signatureswhich are distinctive to each breed.
Since identification technique is not based solely on genes, it does not specifically relate to physical or behavioral traits that characterize particular breeds. Therefore, it is understood that the technique of dog DNA testing doesn’t recognize a bulldog by finding the genes that give it a snub nose, beefy head and squat stature.
Consequently, breeds that are vastly different in appearance quite often might have parallel genetic signatures, which helps clarify some head-scratching results that have been reported. For instance, portions of the signatures of Chihuahuas and some mastiff breeds are maddeningly similar. Therefore, although occasionally a Dog DNA test may show some seemingly off-target results, DNA testing is much more accurate than someone looking at a dog and surmising its heritage.
Written by Dr David Randall, DVM
His father established the clinic in 1977 and the the younger Dr. Randall always knew that he would follow closely in his father’s footsteps. Dr. Randall graduated from the University of Florida, College of Veterinary Medicine in 1985 and began his career at Big Cypress Animal Clinic.