DNA (deoxyribonucleic acid) is composed of a sequence of substances known as nucleotides. It carries the unique blueprint for every individual living organism—from the smallest bacterium to humans. Genes are segments of DNA, and these code for specific proteins that play the central role in building, maintaining, and reproducing a cell.
Dogs have about 20,000 to 25,000 genes that are located along 78 chromosomes (compared to 46 in humans).
In 2005, an international research team led by MIT's Broad Institute published a paper in the journal Nature, describing the sequencing the canine genome. This complete set of dog genes gave scientists, breeders, and owners a powerful tool to better understand and care for dogs.
The research was based on the genetic sequence of Tasha, a female Boxer. This breakthrough gave researchers a tool for identifying genes for specific traits, including diseases, in addition to pinpointing genes and parentage.
Courtesy National Human Genome Research Institute/Broad Institute
Today, DNA testing is used in the following ways:
- Confirming parentage
A technology known as "genetic fingerprinting" is used by law-enforcement throughout the world to positively identify crime suspects. The same technology can be used to provide a DNA snapshot of any individual, canine or human. These profiles serve several functions, including positive identification of a dog, accurate pedigree tracking, and confirmation of parentage. The American Kennel Club offers AKC DNA Profiles service that creates and records the genetic identification of dogs. This voluntary program adds value to breeding programs by giving breeders a way to eliminate concerns and questions about parentage. How does this work? Each gene is present as two copies called alleles. Offspring receive one copy of each gene from each parent. DNA tests to confirm parentage do not use actual genes, but other DNA sequences referred to as markers. These are not functional genes, so the DNA profiles are used only for genetic identity and parentage verification. They do not provide any information about appearance, genetic diseases, or breed.
- Enforcing pet waste laws
The same kind of technology is used to put the finger on poop-law scofflaws. One company—PooPrints by BioPet Laboratories, in Knoxville, Tennessee—has offered a genetic profiling service to managed communities since 2008. Landlords can log each resident's dog into a pet registry. If waste is found in place where it doesn't belong, a sample of cells extracted from the feces can be compared to an individual in a database of genetic profiles of local dogs.
- Determining the mix in mixed-breed dogs
DNA tests are available to reveal what breeds went into creating dogs that are affectionately nicknamed "Heinz 57s." The AKC designates these dogs as Canine Partners. Wisdom Panel, which is owned by Mars Inc., covers all AKC registered breeds, as well as some of the rarer breeds in the Foundation Stock Service listing. The tests cost about $85, and Wisdom Panel says it has sold about 400,000 since the company launched in 2007. Wisdom Panel and other similar tests are available online. Knowing the breed will allow owners to make intelligent choices, based on breed, about healthcare and training. It can also give puppy owners an idea of how large the adult dog is likely to be. Wisdom Panel's tests are being used by the Search Dog Foundation, which takes dogs from shelters and trains them for search-and-rescue, to help assess if a dog's genetic background is well-suited to a certain kind of work.
- Detecting inherited diseases
Breeders have a responsibility to choose the sires and dams that have the best chance of producing sound, healthy puppies. Genetic testing plays a huge role in this, by giving breeders a heads up that there may be a tendency toward a disease lurking in a dog's DNA. The Orthopedic Foundation for Animals, Inc., founded in 1966 as a control database for the orthopedic problem known as dysplasia, now maintains voluntary databases of canine health, some of which is based on X-Rays, some on genetic tests. According to an OFA monograph, "knowledge of the genotypic status is the breeder's most powerful tool for elimination of genetic disease."
Today, there are hundreds of these tests, pinpointing the gene for dog diseases. The AKC Canine Health Foundation has a list of available canine genetic tests, organized by breed. There are 119, but more are being researched and added each day. PennGen, a genetic testing facility operated at the University of Pennsylvania's School of Veterinary Medicine, is a collection of laboratories that coordinate as a not-for-profit unit, that offer routine testing for genetic disease. According to PennGen, more than 900 inherited disorders have been identified in dogs. It maintains a database of available tests, which can be searched by breed or condition. Breed clubs generally list recommended genetic tests.
- Revealing hidden traits
DNA tests are also available for detecting genes for coat color and type. A dog may look like he's a certain color, but may carry the genes for another color, pattern, or texture that may show up in the offspring.
How Can You Get a DNA Test for Your Dog
Several universities and companies offer testing services. Some require blood to be drawn, and this is probably best done by your veterinarian. Others require only a scraping of cells, taken from the inside of the mouth, known as a buccal swab or smear. This video shows how it is done for tests conducted at University of California, Davis. Test kits will provide the materials needed to obtain and ship samples to laboratories.
For more information, visit the AKC DNA Resource Center.