Why Genetic Disease Screening Is Essential for Breeders
The era of selecting breeding stock based solely on appearance and temperament has already ended. Today's responsible breeders are expected to scientifically evaluate genetic health status and plan breeding programs that prevent inheriting genetic diseases to the next generation.
Many genetic diseases are recessive, so carrier parents appear completely healthy in appearance. However, when both parents are carriers, there is a 25-50% chance that affected puppies will be born. Without DNA testing, such risks remain unknown until breeding actually occurs.
Pre-breeding genetic testing is also important from the perspective of after-sales follow-up and guarantees for purchasers. Many canine genetic diseases are difficult to treat after onset, placing significant burden on owners. Screening implementation and disclosure directly impact breeder credibility and trust.
Major Genetic Diseases and Breed-Specific Risks
The types of genetic diseases vary significantly by breed. The following are representative conditions requiring particular attention.
Hip Dysplasia (HD) and Elbow Dysplasia (ED)
These are skeletal disorders common in large breeds such as Labrador Retrievers, German Shepherds, and Golden Retrievers. Testing is performed through OFA (Orthopedic Foundation for Animals) evaluation via X-ray imaging and BVA/HD assessment scores, and it is recommended to use breeding stock graded "Good" or higher.
Progressive Retinal Atrophy (PRA)
A genetic disease in which the retina progressively deteriorates, ultimately leading to blindness. It is commonly seen in Miniature Poodles, Cocker Spaniels, and Border Collies. DNA testing can detect the presence or absence of mutations, with results presented in three stages: Clear (normal), Carrier, and Affected.
MDR1 (ABCB1) Gene Mutation
A mutation common in herding dog breeds such as Collies, Shetland Sheepdogs, and Australian Shepherds, carrying the risk of severe adverse reactions to certain medications (e.g., ivermectin, loperamide). Pre-screening via DNA testing enables appropriate medication management.
Degenerative Myelopathy (DM)
A progressive neurological disease common in German Shepherds and Bernese Mountain Dogs, characterized by hind limb paralysis. Testing for SOD1 gene mutations is available.
Other Major Breed-Specific Disorders
- Dachshunds: Intervertebral Disc Disease (IVDD)
- Cavalier King Charles Spaniels: Mitral Valve Disease (MVD), Syringomyelia
- Bulldogs, French Bulldogs: Cleft Palate, Chondrodystrophy (respiratory complications)
- Boxers: Subaortic Aortic Stenosis (SAS), Arrhythmogenic Right Ventricular Cardiomyopathy
Types of DNA Tests and How to Choose
DNA tests are divided into two main categories based on purpose.
Single-Disease Testing
Testing that examines a single specific genetic mutation. This is ideal when wanting to focus only on diseases critical to a breed (such as PRA or MDR1) or when cost is a consideration. Approximately ¥3,000-¥8,000 per test.
Panel Testing (Comprehensive Multi-Disease)
A test that can screen for over 100 genetic diseases in a single sample collection. Offered by major testing companies domestically and internationally, at approximately ¥15,000-¥40,000 per dog. Panel testing is efficient for new breeders or those working with multiple breeds.
Major Testing Facilities
- Embark (USA): 200+ genetic diseases + pedigree analysis. Available through domestic representatives
- Wisdom Panel (USA): 250+ health markers supported
- Animal Genetics (Multiple locations in Europe and North America): Comprehensive coverage from single diseases to multi-disease panels
- Domestic: Referrals to partner organizations for JKC-registered breeders
Sample collection is primarily done via cheek swab, which can be easily collected at home.
Reading Test Results and Utilizing Them in Breeding Plans
DNA test results are typically presented in three stages.
| Result | Meaning |
|---|
| Clear (N/N) | No relevant mutation. Will not be affected and will not pass to offspring |
| Carrier (N/Mut) | Carries one copy of the mutation but is not affected. Will pass to 50% of offspring |
| Affected (Mut/Mut) | Carries mutations in both alleles. Risk of manifestation in recessive diseases |
The most important aspect of breeding planning is "avoiding carrier-to-carrier matings."
- Clear × Clear → All puppies are Clear (ideal)
- Clear × Carrier → 50% of puppies are Carriers (no manifestation, but genetic transmission occurs)
- Carrier × Carrier → 25% are Affected (nearly prohibitive)
- Affected × Clear → All puppies are Carriers (use cautiously for breeding)
Even carrier individuals with excellent pedigree, conformation, and temperament can be utilized for breeding when paired with Clear partners. The key is not to "completely eliminate carriers" but to "manage so that affected individuals are not produced."
Combining with X-ray and Cardiac Examinations
DNA testing does not cover all genetic diseases. Hip and elbow dysplasia are multifactorial (polygenic) conditions that are difficult to assess through DNA alone and must be combined with X-ray evaluation.
Cardiac disease (MVD, SAS, etc.) follows a standard protocol of auscultation and echocardiography by a board-certified cardiologist. For Cavalier MVD screening, the BMWG protocol (clearance by a cardiologist at age 2.5 years or older) is the international standard.
Thus, responsible breeding requires a combination of "DNA testing + X-ray evaluation + cardiac testing." The cost per breeding dog is approximately ¥30,000-¥80,000, but this is essential as a foundational investment in producing healthy puppies.
Record Keeping and Disclosure to Purchasers
Once testing is completed, it is important to maintain the test report and disclose results to puppy purchasers. Disclosure not only builds trust but also helps purchasers make informed decisions regarding future health management and breeding choices.
The JKC breeding certification system and excellent breeder certification include health testing implementation and disclosure as evaluation criteria. It is recommended to maintain test results as digital data and standardize by attaching them to puppy sales materials and contracts. Transparency in genetic testing significantly contributes to long-term brand value.
