DNA Testing for Dogs: What Commercial Tests Can and Cannot Tell You
The commercial dog DNA testing market has expanded rapidly over the past decade. Tests that once required specialist laboratories and substantial cost are now available as postal swab kits for under fifty pounds, and their popularity has grown accordingly. Some of what these tests offer is genuinely useful for breeders and owners alike. Some of it is marketed in ways that exceed what the science can reliably support. Knowing the difference matters.
What DNA Tests Are Actually Doing
Commercial dog DNA tests typically work by analysing a saliva or cheek swab sample for specific known genetic variants. The most scientifically robust tests look for variants that have been well-characterised in peer-reviewed research — mutations where the inheritance pattern is understood, where the relationship between genotype and disease is established, and where the clinical significance of each result is clear.
When a test identifies a dog as clear, carrier, or affected for a condition like progressive retinal atrophy or progressive rod-cone degeneration, it is detecting a specific variant that causes that condition in that breed. The result is binary and meaningful: a clear dog does not carry the variant tested, a carrier has one copy and will not develop the disease but can pass it to offspring, and an affected dog has two copies and will or is likely to develop the condition.
Where Commercial Tests Perform Well
Single-gene conditions with clear autosomal recessive or dominant inheritance patterns are where DNA testing delivers its most reliable results. These include conditions like degenerative myelopathy, exercise-induced collapse in Labradors, hereditary nasal parakeratosis in Labradors, and the various forms of PRA found in specific breeds. For these conditions, DNA testing allows breeders to make informed mating decisions that progressively reduce the frequency of the causative variant in the population without eliminating dogs that are merely carriers.
Breed identification panels have also shown reasonable accuracy in mixed-breed dogs, particularly at identifying dominant breed ancestry. These results are not as precise at detecting minor contributions or distant ancestry, but for understanding the broad genetic background of a rescue dog or crossbreed, they provide useful information.
Colour and trait testing — for coat colour, furnishings, shedding, and similar characteristics — is among the most reliable application of commercial DNA testing. These traits are controlled by a relatively small number of well-characterised variants, and test results in this area are generally accurate and reproducible.
Where Commercial Tests Overreach
The limitations of commercial tests become significant when examining their broader health panels. Many popular testing platforms now offer screening for dozens or even hundreds of conditions. The scientific basis for some of these inclusions is considerably weaker than for well-characterised single-gene conditions.
Several issues arise regularly. Some tests screen for variants that have been identified in research but where the penetrance — the proportion of dogs carrying the variant that actually develop the condition — is low or uncertain. A positive carrier result for such a condition may alarm breeders or owners without providing a sound basis for action. Other tests apply variants found in one breed to another breed where the same variant may have no clinical significance, because the genetic context differs.
Polygenic conditions — those controlled by many genes interacting with environment — are not reliably predicted by current commercial tests. Hip dysplasia, epilepsy, and most behavioural traits fall into this category. Some companies offer panels that claim to provide risk scores for these conditions, but the predictive value of such scores in individual dogs is modest at best and can be actively misleading at worst. A dog with a high genetic risk score for a polygenic condition may never develop it; a dog with a low score may develop it anyway.
Breed Ancestry Tests and Their Limits
Ancestry testing in dogs raises particular questions around accuracy thresholds. Tests are typically calibrated against reference populations of purebred dogs. The accuracy of breed identification depends on how well-represented each breed is in the reference database, and databases vary between providers. Rare breeds or breeds with limited samples in a given database may be misidentified or listed as a related breed. Where ancestry results will be used to make any significant decision, treating them as indicative rather than definitive is sensible.
Choosing a Reputable Test
For breeders making health-related decisions, using laboratories that are accredited, transparent about their methods, and whose variants have been peer-reviewed and validated is important. In the UK, the Animal Health Trust (now succeeded by the veterinary genetics laboratory at the University of Surrey), Laboklin, and Orivet are among the providers whose tests for established conditions carry scientific credibility. Tests submitted through the Kennel Club's health testing programme are validated against published research and results are recorded on official health records.
When evaluating a multi-condition panel, it is worth checking which specific variants are tested for each condition, whether those variants have published research linking them to disease in the breed being tested, and what the laboratory recommends doing with a carrier result. If this information is not readily available from the provider, that itself is informative.
Integrating Results Sensibly
DNA test results should be interpreted in the context of the specific breed, the condition being tested, and the other health information available. A carrier result for a well-characterised recessive condition in a breed where that condition is known to occur is meaningful and should inform breeding decisions. A carrier result for an obscure variant on a bulk panel, with no clear guidance on its significance in that breed, warrants consultation with a veterinary geneticist before drawing any conclusions.
The technology underlying commercial dog DNA testing is advancing quickly. The science supporting individual test applications, however, advances more slowly. Using tests that have kept pace with the evidence — and approaching those that have not with appropriate scepticism — is the basis for using this genuinely useful tool responsibly.