In the world of dog breeding, genetic testing has become a tool for identifying potential health risks. Many pet owners now expect genetic testing as a standard part of purchasing a dog, believing it guarantees health and longevity. Breeders and pet owners alike turn to these tests in hopes of eliminating inherited diseases and ensuring healthier dogs. While genetic testing provides valuable information, it also has significant limitations that are frequently overlooked.
Adding to the complexity is the rapid commercialization of genetic testing. As with many emerging scientific advancements, capitalism and marketing often outpace the actual science. Companies eager to profit from new technology promote genetic tests as definitive diagnostic tools, despite the fact that canine genetics is still in its early stages. While in the fine print, genetic testing companies might include caveats about interpreting and relying on the results, this is nowhere near as prominent as the claims of testing for 200+ diseases. This ultimately leads to misinterpretation of results, unnecessary fear, and misguided breeding decisions. The promise of "DNA-certified healthy puppies" may sound appealing, but given the current limitations, it becomes more of a sales pitch than solid science. This ultimately leads to a distrust of the science.
Relying too heavily on genetic markers without considering the broader implications can lead to unintended consequences, including a loss of genetic diversity and the potential emergence of new health issues. Understanding the limitations of genetic testing is crucial for making informed decisions that prioritize both health and sustainability in breeding practices.
Incomplete Information: The Limitations of Genetic Testing
Since the domesticated dog genome was first mapped in 2005, genetic testing for inherited diseases has become more common. However, the technology is still in its relative infancy, and there are significant limitations to what is currently understood.
Why Genetic Testing Isn’t a Perfect Solution:
- Not all conditions have known genetic markers – While genetic markers have been identified for many diseases, there are still countless conditions with no clear genetic link
- New mutations are continually being discovered; just in January 2025, researchers identified three likely causal variants in dogs: one in Lancashire Heelers (Charcot-Marie-Tooth disease 1J with amelogenesis imperfecta), one in English Cocker Spaniels (Retinopathy with vitamin E deficiency), and one in Labrador Retrievers (Retinal atrophy, progressive, GTPBP2-related).
- Breed-specific mutations – A mutation linked to a disease in one breed may not have the same effect in another breed.
- Complex conditions – Some diseases are caused by multiple genetic mutations, but only a few of them may have been identified.
The Reality: A positive test result does not always mean a dog will develop a disease, just as a negative test does not guarantee health.
False Positives: Correlation vs. Causation
Did you know? In human genetics, fewer than 2% of candidate gene studies hold up to further investigation. Scientists now require much stronger evidence before declaring a genetic variant to be "disease-causing."
Why This Matters for Dogs:
While Genome-Wide Association Studies (GWAS) have become more common, many canine genetic tests are still based on small-candidate gene studies that must be reassessed using more advanced methods.
The Takeaway:
A mutation correlated with a disease is not the same as a mutation causing a disease. Pet owners and breeders should interpret test results with caution and consult a genetic expert before making breeding or health decisions.
The Unseen Risk: Hidden and Unknown Genetic Mutations
Breeding only for known disease-free genes now may create problems later.
Why? Unknown mutations may spread through a breed until they become a problem years later.
How? Some conditions take generations to appear, making them hard to detect until it’s too late. Example: If breeders aggressively remove all dogs carrying one mutation, they may unintentionally increase the frequency of another unknown mutation, leading to future health crises.
Waiting until a disease becomes prevalent to start genetic testing is risky—by then, it may be too widespread to control.
Preventing the Need for Genetic Rescue
The genetic rescue of the California Condor is often hailed as a triumph—after all, only 22 remained in 1982, and as of 2022 there are 561. But when it comes to dogs, we should never allow any breed to reach such a critical state.
One of the biggest challenges in dog breeding is ensuring that no breed becomes so genetically compromised that rescue efforts are necessary. Genetic rescue—the introduction of new genetic material into a shrinking or inbred population—is a complex and risky process. It is a last resort, undertaken only when genetic bottlenecks and inbreeding have caused severe health problems or dangerously low population numbers. While it can sometimes be effective, it comes with major risks, including unforeseen health issues, loss of breed characteristics, and difficulties in maintaining a stable gene pool.
Rather than relying on genetic rescue as a solution, we must focus on preserving genetic diversity before problems arise. Sustainable breeding practices should prioritize long-term health over short-term gains. Over-selecting for specific traits—whether for aesthetics or to eliminate certain diseases—can have unintended consequences, such as reducing beneficial genetic variation and allowing new health problems to emerge.
A responsible breeding approach includes:
- Promoting genetic diversity within breeds rather than narrowing the gene pool unnecessarily.
- Limiting the overuse of popular sires, which can rapidly spread both desirable and harmful genetic traits.
- Using genetic testing as a tool, not a rule—balancing disease risk reduction with the need for diversity.
By adopting a balanced, science-based approach, we can prevent drastic genetic interventions in the future. The goal should always be to produce healthy, well-rounded dogs while maintaining genetic diversity—ensuring that no breed ever reaches a point where genetic rescue is the only option.
“Simulating Genetic Management Strategies and Genetic Defects in Dogs"
The researcher investigated the effects of different genetic management strategies on the allele frequencies of genetic defects in dog breeding. The study focused on small and medium-sized populations using the Pointer simulation program to model various breeding strategies. The goal was to determine which strategies effectively reduce genetic defects while maintaining genetic diversity.
Key Findings:
- Dog Breeding Challenges: Many dog breeds have high levels of inbreeding and genetic defects due to closed populations and historical breeding practices.
- Simulated Breeding Strategies:
- Excluding Carriers – Led to rapid population extinction due to the removal of too many individuals.
- Least Related Breeding – Reduced inbreeding but was less effective at eliminating genetic defects.
- Mean Kinship Selection – Most effective at reducing inbreeding while preventing the fixation of harmful alleles.
- Breeding Cap on Popular Sires – Helped manage inbreeding levels but did not significantly impact genetic defect frequencies.
- Key Observations:
- Larger populations retained more genetic diversity and were more resilient to genetic defects.
- The strength and age of onset of genetic diseases impacted the effectiveness of breeding strategies.
- Mean Kinship was the most balanced strategy, reducing genetic defects without causing population decline.
The study ultimately highlights the importance of strategic genetic management in dog breeding. Breeding decisions should balance reducing genetic defects with maintaining population viability.
Conclusion: Smart Breeding for a Healthy Future
Genetic testing is a valuable tool, but it should not be the sole deciding factor in breeding decisions. Breeding a carrier with a genetically clear dog (instead of eliminating all carriers) helps maintain genetic diversity. Always check if a genetic mutation is validated for your breed before making medical or breeding decisions. Search By Breeds - DogWellNet
For Breeders:
- Focus on reducing genetic diseases gradually rather than eliminating all carriers at once.
- Educate yourself about genetic diversity and the risks of narrowing the gene pool too much.
For Pet Parents:
- Ask about genetic testing when getting a puppy, but don’t let it be the only factor in your decision.
- Work with a veterinarian familiar with genetics to understand your dog’s results*
- Many, if not most, vets aren’t going to be familiar enough with genetics generally to be able to truly advise owners or breeders.
- Take extreme caution, and don’t rely on genetic testing when making medical decisions, especially when the symptoms also match treatable conditions. Some diseases may only affect 1 out of 100 dogs that test positive for a specific mutation.
Final Thoughts
Genetic science is advancing, but it is not perfect, and probably never will be. What is currently understood about canine genetics is dwarfed by what is not, with many genetic interactions, mutations, and health implications yet to be uncovered. The best approach is and will be for the considerable future a balanced strategy that prioritizes both genetic diversity and disease prevention—for the future of all dogs.
References
Bergsma, R (2022), Simulating genetic management strategies & genetic defects in dogs (Registration number: 1035497)[MSc thesis Animal Sciences – Animal Breeding & Genomics, Wageningen University https://edepot.wur.nl/575638
Ioannidis JP, Tarone R, McLaughlin JK. The false-positive to false-negative ratio in epidemiologic studies. Epidemiology. 2011 Jul;22(4):450-6. doi: 10.1097/EDE.0b013e31821b506e. PMID: 21490505.