Understanding Dog Genetics and Health Testing

What hereditary health conditions are — and why they matter

Selective breeding concentrates traits — including unhealthy ones. When breeders prioritise appearance, temperament, or working ability without tracking health outcomes, certain genetic mutations spread through the gene pool. The result: conditions like hip dysplasia, progressive retinal atrophy, and dilated cardiomyopathy occur at measurably higher rates in specific breeds than in mixed-breed dogs.

The good news: for most major hereditary conditions, health tests exist. Breeders who use them and make responsible pairing decisions significantly reduce the probability that their puppies will develop those conditions. This is the difference between a puppy that costs $1,800 with full health testing and a $600 puppy with none — often, the true cost reverses over the dog's life.

The OFA testing system

The Orthopedic Foundation for Animals (OFA) is the primary US registry for canine health testing results. Their publicly searchable database (ofa.org) allows anyone to look up any registered dog's health certification results.

OFA hip and elbow evaluation

Hip dysplasia — malformation of the hip socket — is one of the most common orthopedic conditions in dogs, with rates particularly high in Labradors, German Shepherds, Golden Retrievers, Rottweilers, and large breeds generally. OFA hip evaluation uses X-rays submitted at 24 months or older; the hips are graded Excellent, Good, Fair (all passing, eligible for breeding), Borderline, Mild, Moderate, or Severe.

What to ask breeders: Both parents should have OFA hip evaluation results of at least "Good." OFA grades are public — verify them at ofa.org by name or registration number.

CAER eye certification

The Companion Animal Eye Registry (CAER), operated through OFA, covers hereditary eye diseases examined by a board-certified veterinary ophthalmologist. Tests for progressive retinal atrophy (PRA), hereditary cataracts, collie eye anomaly, and other breed-specific eye conditions.

CAER exams expire after 12 months for breeding purposes because some conditions are late-onset. Ask to see documentation dated within the past year for any breeding dog.

Cardiac evaluation

Relevant primarily for breeds with elevated cardiac disease rates: Cavalier King Charles Spaniel (mitral valve disease), Doberman Pinscher (dilated cardiomyopathy), Boxer, and others. OFA cardiac exams are performed by cardiologists. For Cavaliers specifically, the CKCS Mitral Valve Disease breeding protocol is the current standard among responsible breeders.

Other OFA-registered certifications

• Elbow dysplasia (same X-ray protocol as hips)
• Thyroid function (autoimmune thyroiditis testing)
• von Willebrand disease (bleeding disorder, common in Dobermans)
• Degenerative myelopathy (DM) — genetic test; relevant for German Shepherds, Corgis
• Exercise-induced collapse (EIC) — genetic test; relevant for Labradors
• MDR1 drug sensitivity mutation — relevant for herding breeds (Australian Shepherd, Collie)

DNA and genetic panel testing

In addition to physical evaluations, DNA-based genetic tests can identify specific mutations in a dog's genome. These tests are done once in a dog's life and do not expire. Several laboratories offer breed-specific panels:

When breeders reference genetic testing, ask for the original certificate from the laboratory — not a verbal summary. The certificate shows the dog's name, registration number, test date, and specific result (clear/carrier/affected) for each condition tested.

Breed-specific health testing priorities

Not all tests apply to all breeds. Responsible breeders follow the health testing requirements recommended by their breed's national club. Common breed-specific priorities:

Your breed's national parent club website lists the current recommended health testing requirements. Breeders who do not follow their own breed club's minimum requirements are a red flag.

Red flags: responsible breeders vs puppy mills

Frequently asked questions

What is OFA health testing?

The Orthopedic Foundation for Animals (OFA) is a non-profit that maintains a health testing database for dogs. Breeders submit health test results — hip and elbow X-rays, cardiac exams, eye exams, and genetic tests — which OFA evaluates and stores publicly. You can search any registered dog's OFA results by name or registration number at ofa.org.

What is CAER eye certification?

The Companion Animal Eye Registry (CAER), administered by OFA, is the standard eye examination for breeding dogs. A board-certified veterinary ophthalmologist examines the dog for hereditary eye diseases. CAER certifications should be dated within the past 12 months for breeding dogs, as some conditions are late-onset.

What does "clear" mean in genetic testing?

"Clear" (also called "normal" or "negative") means the dog does not carry the mutation tested. "Carrier" means the dog has one copy of a mutation but is typically unaffected — a carrier bred to a clear dog produces no affected puppies. "Affected" means the dog has two copies and will express the condition. Responsible breeders use genetic testing to ensure at-risk pairings are avoided.

How do I verify a breeder's health testing claims?

OFA results are publicly searchable at ofa.org — search by the dog's registered name or OFA number. CAER results are also in the OFA database. For genetic panel tests from private labs (Embark, Wisdom Panel, PennGen), ask to see the original certificate from the lab — not just a breeder's statement. Never accept "I know the lines are healthy" without documentation.

What are the red flags for a puppy mill or irresponsible breeder?

Key red flags: no health testing documentation for both parents; puppies available immediately (responsible breeders have waiting lists); multiple breeds available simultaneously; no questions asked of you as a buyer; meeting in a car park rather than at the home; selling primarily through pet shop intermediaries; parents not available to meet; price significantly below breed average (often cut-cost welfare); and pressure to commit quickly.