What Genetic Testing Can and Can't Tell You About Your Pet
Genetic (or DNA) testing is an easy way to uncover valuable information about your pet—from parentage identification to health screening. UC Davis helped pioneer animal genetic testing in the 1960s and is internationally recognized as an expert in the field today—a field that has rapidly expanded in the last decade. But when and why should you consider a DNA test for your pet?
Genetic Testing 101
Genes are biological instructions, with half of the information contributed by each parent, that make up the unique blueprint of the life (genome) of each individual. Sometimes, small changes (variants) occur. These variants are responsible for differences within and across species. They also make genetic testing possible since tests are designed to look for these differences.
The UC Davis Veterinary Genetics Laboratory (VGL) provides hundreds of genetic tests across 24 species. Most samples received are from horses, dogs, cats, cattle, and goats—and most tests are for parentage and for known variants that cause, or are risk factors for, diseases or influence coat colors.
“Genetic testing is a powerful tool that has been used for decades to preserve the integrity of breeds,” said VGL director Dr. Rebecca Bellone. “Today, it is increasingly utilized by animal owners, breeders, and veterinarians to make informed mating and management decisions.”
The Whys
Breeders utilize genetic tests to evaluate potential parents for specific variants known to affect health. The goal is to make informed breeding decisions to reduce heritable health concerns in breeding populations. If you are acquiring a purebred, research inherited conditions known in the breed, and ask the breeder which tests they run, the status of the animal and/or the status of their parents.
“For recessive conditions, testing can allow people to safely breed carriers to unaffected animals while avoiding producing offspring affected with a devastating disease,” said Dr. Danika Bannasch, the Maxine Adler Endowed Chair in Genetics at UC Davis.
Owners may submit samples for genetic testing to gather information about current or future health concerns. Early diagnosis and appropriate treatments offer the best chances for a positive outcome. Results from genetic testing may guide future management of environmental factors that could trigger diseases, such as nutrition, weight, exercise, infection, allergies, surgery, and medication.
In recent years, dog breed identification tests have exploded in popularity. These tests compare your dog’s DNA with a company-specific DNA database from dogs of different breeds and report which breeds are the closest match. Similarly, ancestry testing is available in horses through Texas A&M University, which returns broad results that provide ancestral geographic regions, but generally does not specify the percentage makeup of particular breeds.
Breed or ancestry tests may help determine which genetic tests may be appropriate when the breed is unknown, but it is important to work with your veterinarian before using results to make any medical decisions for your pet.
The Hows
You have likely heard about human genetic testing services such as 23andMe® or AncestryDNA®. You may have even submitted a sample and received reports about your unique genetic makeup. Human and animal DNA is very similar, so the same molecular technologies can be used across species.
DNA is stored in the cell nucleus. To extract DNA for testing, samples have to contain cells that have a nucleus—white blood cells, epithelial cells, etc. For dogs and cats, DNA samples are usually collected from cheek swabs. Hair samples are commonly submitted for DNA testing in horses, cattle, and other livestock. These samples are easy to collect and can be shipped to the laboratory without any special packaging.
There is no upper or lower age limit for DNA testing, but there are some caveats when sampling very young animals. The VGL provides instructions for sample collection, along with easy-to-follow pictures and videos on their website.
The Limits
Genetic testing is powerful technology, but it is important to work with your veterinarian to interpret results, especially when making medical decisions. Misinterpretation or over-interpretation of results in the absence of appropriate context and knowledgeable counseling can be problematic.
Animal genetic testing has followed advances in human genetic testing, but unlike in people, animal genetic testing is not regulated. Many veterinarians and scientists urge caution when it comes to direct-to-consumer genetic tests since there are no industry-wide standards and companies do not disclose their methodologies or quality controls.
An advantage of testing through the VGL is that the laboratory adheres to strict quality controls and only offers scientifically validated tests. It also boasts ISO/IEC 17025 accreditation by the American National Standards Institute National Accreditation Board (ANAB), the highest level of accreditation available to testing laboratories.
Annual ANAB assessment ensures clients can be confident in the exceptional testing services provided.
“The VGL is committed to providing accurate results,” said Bellone. “We employ many quality control checks throughout our accredited testing procedures to ensure the highest level of accuracy.”
The Future
Most available genetic tests screen for conditions and traits caused by a single variant. However, many diseases, such as hip dysplasia, are caused by more than one gene, or result from interactions between genes and the environment. Research on many of these conditions is underway.
In the future, genetic information from DNA tests could be combined with other diagnostics to create treatment and management plans targeted specifically to your pet’s biology. This precision medicine approach could maximize the effectiveness of medications, minimize side effects, and lead to faster resolution or stabilization of health conditions.
“For complex diseases, it is important to consider the roles of genetics and the environment,” said Dr. Carrie Finno, professor of genetics and director of the UC Davis Center for Equine Health.
“Our Pioneer 100 Horse Health Project leverages multi-omics technologies (genomics, proteomics, metabolomics, etc.) and medical records over time. The goal is to determine, for example, how a patient will respond to one drug versus another to target treatments for optimal outcomes.”
Research investments, growing consumer interest, and continued advancement in scientific discoveries suggest that the use of genetic testing will continue to rise, especially in pets. A 2021 report by Global Market Insights, Inc. projected that the animal genetics market will exceed $6.4 billion by 2027, with the canine sector leading the way. Further research and education are needed to help owners utilize genetic testing results and enable veterinarians to provide genetic counseling.
Contact the VGL at:
www.vgl.ucdavis.edu
(530) 752-2211