Genetic Diseases in Dogs: What Every Breeder Must Know Before Pairing

The health testing guide serious breeders rely on

You've found a great stud. The conformation is right, the temperament is solid, and the genetics look promising on paper. But before any breeding decision is final, one question has to be answered: what diseases could this pairing pass on?

Genetic diseases are among the most heartbreaking — and most preventable — outcomes in dog breeding. This guide breaks down the most important hereditary conditions, how they're inherited, which breeds are most at risk, and what testing you should require before every breeding.

A note on purpose: This guide is for educational use. Always work with a licensed veterinarian or board-certified veterinary geneticist when making health-based breeding decisions.

How Genetic Diseases Are Inherited

Before diving into specific conditions, it helps to understand how these diseases move through generations. Most fall into one of three categories:

Autosomal Recessive

The most common pattern in dog breeding. A dog must inherit two copies of the defective gene — one from each parent — to be affected. Dogs with only one copy are carriers: they look and act healthy but can pass the gene to offspring.

The risk: Two carrier parents have a 25% chance of producing an affected puppy with every litter. This is why carrier-to-carrier pairings are the leading cause of genetic disease in purpose-bred dogs.

The fix: DNA test both parents. Pair Affected × Clear or Carrier × Clear to eliminate affected puppies entirely.

Autosomal Dominant

Only one copy of the defective gene is needed to cause the disease. An affected dog has a 50% chance of passing it to each puppy. These conditions are harder to hide — affected dogs typically show symptoms — but can persist in lines where symptoms are subtle or late-onset.

X-Linked

The defective gene is carried on the X chromosome. Males (XY) are typically affected when they inherit one copy; females (XX) are usually carriers unless they inherit two copies. More common in certain breeds than others.

The Most Important Conditions to Screen For

Hip and Elbow Dysplasia

What it is: Malformation of the hip or elbow joint causing abnormal movement, pain, and progressive arthritis. One of the most common orthopedic conditions in dogs.

How it's inherited: Polygenic (multiple genes) with strong environmental influence. Scores are used rather than simple clear/carrier/affected status.

Breeds most affected: Bernese Mountain Dog, Bernedoodle, Golden Retriever, German Shepherd, Labrador Retriever, Rottweiler, French Bulldog

Testing required:

• OFA (Orthopedic Foundation for Animals) — Hip and elbow radiographs evaluated and graded. Dogs rated Excellent, Good, or Fair pass; Fair is borderline. Dogs should be at least 2 years old for a final OFA rating.
• PennHIP — Alternative method measuring hip laxity. Provides a distraction index and percentile ranking within the breed.

Breeder standard: Both parents should have passing OFA or PennHIP scores before any breeding. Never pair two dogs with borderline or failing hip scores.

Progressive Retinal Atrophy (PRA)

What it is: A group of inherited eye diseases that cause the photoreceptors in the retina to degenerate over time, leading to progressive vision loss and eventual blindness. There is no treatment or cure.

How it's inherited: Most forms are autosomal recessive. There are multiple distinct genetic variants of PRA — different mutations can cause the same clinical outcome.

Breeds most affected: Miniature Poodle, Toy Poodle, Standard Poodle, Cavapoo, Cocker Spaniel, Labrador Retriever, Bernedoodle (via Poodle lines)

Testing: DNA panel tests are available through Embark, Optigen, and Animal Genetics. CERF/OFA eye exams by a board-certified veterinary ophthalmologist are also recommended annually for breeding stock.

Key point: Because PRA has multiple genetic variants, make sure the DNA test panel covers the variant(s) relevant to the breeds in your dog's background — especially if your dog has Poodle ancestry.

Von Willebrand Disease (vWD)

What it is: The most common inherited bleeding disorder in dogs. Caused by a deficiency of von Willebrand factor, a protein essential for normal blood clotting. Affected dogs may bleed excessively after injury or surgery.

How it's inherited: Most commonly autosomal recessive (Type I and III), though Type II behaves differently.

Breeds most affected: Doberman Pinscher, German Shepherd, Golden Retriever, Bernedoodle (via Bernese Mountain Dog lines), Scottish Terrier, Shetland Sheepdog

Testing: DNA test available through VetGen and other labs. Simple clear/carrier/affected result.

Degenerative Myelopathy (DM)

What it is: A progressive neurological disease that affects the spinal cord, causing hind limb weakness and eventual paralysis. Typically presents in middle to older age dogs (7–14 years). There is no cure.

How it's inherited: Autosomal recessive. Dogs with two copies of the SOD1 mutation are at risk — though not all at-risk dogs develop clinical disease, suggesting additional environmental or genetic factors.

Breeds most affected: German Shepherd, Boxer, Welsh Corgi, Bernese Mountain Dog, Bernedoodle, Rhodesian Ridgeback

Testing: DNA test available through Embark, OFA, and others. Results: Clear, Carrier, or At Risk.

Breeder note: Because not all at-risk dogs develop DM, breeding decisions with DM are nuanced. Many breeders avoid At Risk × At Risk pairings but will breed a Carrier to a Clear without concern.

Bernedoodle-Specific Health Priorities

Bernedoodles inherit health risks from both the Bernese Mountain Dog and Poodle parent lines. Responsible Bernedoodle breeders should screen for risks from both sides.

From the Bernese Mountain Dog Side

Histiocytic Sarcoma One of the leading causes of cancer-related death in Bernese Mountain Dogs. This aggressive cancer of histiocyte cells (immune cells) has a strong hereditary component in the BMD breed. While no commercial DNA test currently exists to predict individual risk, knowing the health history of the dog's Bernese lines is important.

Bloat (Gastric Dilatation-Volvulus / GDV) Deep-chested breeds including Bernese Mountain Dogs are at elevated risk for bloat, a life-threatening condition where the stomach twists on itself. Though not directly DNA-testable, it's a known risk to discuss with buyers and factor into management recommendations.

Recommended tests for the Bernese parent or Bernedoodle breeding stock:

• OFA Hip and Elbow (pass required)
• OFA Cardiac evaluation
• OFA Eye exam (CAER)
• DM DNA test
• vWD DNA test

From the Poodle Side

Addison's Disease (Hypoadrenocorticism) Poodles have one of the highest rates of Addison's disease of any breed — a condition where the adrenal glands fail to produce sufficient cortisol and aldosterone. Genetic basis is suspected but not fully mapped; no reliable DNA test is yet available. Ask breeders about Addison's history in the lines.

Sebaceous Adenitis An inflammatory skin disease affecting the sebaceous glands, leading to hair loss and skin scaling. Most common in Standard Poodles. OFA maintains a registry for SA; biopsy-confirmed dogs can be submitted. Breeding affected dogs is discouraged.

Recommended tests for the Poodle parent:

• OFA Hip
• PRA DNA panel (covering Poodle-specific variants)
• vWD DNA test
• OFA Eye exam (CAER)
• Embark breed health panel (covers 200+ conditions)

French Bulldog-Specific Health Priorities

French Bulldogs are a brachycephalic (short-faced) breed, and their unique structure creates both mechanical health concerns and elevated genetic disease risks. Responsible French Bulldog breeders take health seriously — the breed's popularity has unfortunately led to irresponsible practices that have worsened health outcomes industry-wide.

Brachycephalic Obstructive Airway Syndrome (BOAS)

What it is: A group of anatomical abnormalities — narrow nostrils (stenotic nares), elongated soft palate, narrowed trachea, and everted laryngeal saccules — that obstruct normal breathing. Ranges from mild exercise intolerance to severe respiratory distress.

How it works: Structural, with strong hereditary influence. Breeding dogs with extreme conformations (very flat faces, very narrow nostrils) significantly increases risk in offspring.

Evaluation: The BOAS Functional Grading System is used by veterinary specialists to assess severity. Breeding dogs should be grade 0 or 1. Never breed a dog that has had corrective airway surgery — this doesn't remove the genetic risk and producing puppies likely to need surgery is poor practice.

Intervertebral Disc Disease (IVDD)

What it is: Degeneration and herniation of the cushioning discs between vertebrae, causing pain, nerve damage, and in severe cases, paralysis. French Bulldogs have a high incidence due to their chondrodystrophic body type.

How it's inherited: The chondrodystrophy mutation (CDDY) that causes the low-rider body type also predisposes dogs to IVDD. This is a dominant mutation — essentially every French Bulldog carries it.

Testing: DNA tests for CDDY/IVDD risk are available through Embark. While all Frenchies carry the mutation, testing can still identify dogs with two copies (higher risk) vs. one copy.

Breeder note: Given the universal nature of this mutation in the breed, the focus shifts to avoiding extreme conformations and selecting for dogs with documented longevity and minimal spine issues in their lines.

Hereditary Cataract (HSF4 / HC)

What it is: Cataracts caused by a mutation in the HSF4 gene, leading to progressive lens opacity and vision impairment. Distinct from age-related cataracts.

How it's inherited: Autosomal recessive.

Testing: DNA test available through Embark, Animal Genetics, and others. Clear/Carrier/Affected result. Avoid Carrier × Carrier pairings.

Congenital Heart Disease

French Bulldogs have elevated rates of various congenital cardiac defects. OFA cardiac evaluation by a board-certified cardiologist is recommended before breeding.

Recommended tests for French Bulldog breeding stock:

• OFA Hip (given their structure, passing is important)
• BOAS functional grading (grade 0–1 required)
• OFA Cardiac evaluation
• Hereditary Cataract DNA test (HSF4)
• OFA Eye exam (CAER)
• Embark full health panel

Building a Health-First Breeding Program

The Rule: Test Before You Breed

There is no responsible substitute for health testing. "My dogs have always been healthy" is not a testing protocol. Genetic carriers show no symptoms — they only reveal their status when paired with another carrier.

At minimum, every breeding dog should have:

1. OFA hip and elbow radiographs (passing grade)
2. OFA eye exam (CAER, current within 12 months)
3. DNA panel covering the conditions most common in their breed(s)
4. Cardiac evaluation if indicated by breed risk

How to Read DNA Test Results

The safest pairing is always Clear × Clear. The acceptable pairing for maintaining genetic diversity is Carrier × Clear — which produces 50% Clear and 50% Carrier offspring, but no Affected puppies.

Recommended DNA Testing Labs

Frequently Asked Questions

Do I have to test if my breeder says the lines are healthy?

Yes. Carrier dogs are healthy. They carry genetic conditions without any symptoms. The only way to know a dog's carrier status for recessive diseases is through DNA testing. "Healthy lines" doesn't mean "tested lines."

My dog passed an OFA hip exam — is that enough?

OFA hips cover one condition. Depending on your breed, you may also need to test for eye conditions, bleeding disorders, neurological conditions, and more. Check the OFA's breed-specific recommendations for a complete list.

Is it ever okay to breed a carrier?

Yes — breeding a Carrier to a Clear is an accepted practice for maintaining genetic diversity while preventing affected puppies. Every puppy from this pairing will be either Clear or a Carrier, never Affected. Buyers of Carrier puppies should be informed so they can make appropriate testing decisions before their own future breedings.

How often do I need to retest?

DNA tests are done once — your dog's genotype doesn't change. OFA hip and elbow results are permanent after the age of 2. Eye exams (CAER) and cardiac evaluations should be renewed annually for active breeding dogs.

What's the most important test for a Bernedoodle breeder?

At minimum: OFA hips on both parents, PRA DNA panel (Poodle lines), DM DNA test (Bernese lines), and vWD. A full Embark panel on both parents covers all of these and more.

What's the most important test for a French Bulldog breeder?

BOAS functional grading is arguably the most important and most overlooked. Beyond that: OFA hips, hereditary cataract DNA (HSF4), OFA cardiac, and a full DNA health panel.

© The Stud Dog · thestuddog.com · This article is for educational purposes. Always consult with a licensed veterinarian or board-certified veterinary geneticist for health-based breeding decisions.