What Is a DNA Clear Dog? Clear, Carrier, and At Risk Results Explained

"DNA clear" is one of the most important terms in modern dog breeding — but it is often misunderstood, overstated, or applied too broadly. Understanding what it actually means protects your breeding program.

What "DNA Clear" Means

When a dog tests DNA Clear (also labeled N/N, Normal, or Negative) for a specific genetic mutation:

• The dog carries zero copies of the tested mutation
• The dog cannot develop the associated disease from this specific mutation
• The dog cannot pass this specific mutation to any offspring
• Two Clear dogs cannot produce offspring affected by this mutation

The key phrase is "this specific mutation." DNA clear refers to one test result for one mutation. A dog clear on a 250-condition panel has been tested for 250 specific mutations — but there are more canine genetic diseases than any single panel tests for.

What "Carrier" Means

A Carrier (also labeled N/mut, Heterozygous, or +/-) carries one copy of the tested mutation.

For autosomal recessive diseases (the vast majority of conditions on DNA panels):

• The Carrier dog is completely healthy — one copy causes no disease
• The Carrier can pass the mutation to approximately 50% of offspring
• Breeding a Carrier to a Clear dog produces zero affected offspring (safest approach)
• Breeding two Carriers produces 25% affected offspring on average

For dominant or incompletely dominant diseases:

• One copy may cause some disease expression in the Carrier itself
• Examples: MDR1, HSF4 cataracts in some breeds, PLL

What "At Risk" or "Affected" Means

An At Risk or Affected dog (also labeled mut/mut, Homozygous, or +/+) carries two copies of the tested mutation.

For recessive diseases: the dog is at risk for or will develop the disease. For some conditions: penetrance is incomplete — not every two-copy dog develops the disease (DM is a well-known example — not all DM At-Risk dogs develop paralysis).

What DNA Clear Does NOT Mean

Clear does not mean healthy. A dog can test Clear on 250 conditions and still:

• Develop conditions caused by untested mutations
• Have non-genetic health problems (infections, injuries, structural issues, cancer)
• Carry mutations on conditions not included in the panel

Clear on one PRA mutation doesn't mean clear of all PRA. Multiple distinct mutations cause PRA in dogs. A dog who tests Clear for prcd-PRA may still carry GR-PRA1, GR-PRA2, or another variant.

Clear does not mean the offspring will be clear. A Clear dog bred to an unrelated dog (who may be a Carrier) will produce some Carrier offspring. Clear × Clear is the only combination that produces all Clear offspring.

Using DNA Results in Breeding

*Carrier × Carrier is avoidable and should be avoided for any condition where affected offspring have significant health consequences.

Summary

DNA Clear means a dog carries zero copies of a specific tested mutation and cannot contribute that mutation to offspring. Carrier means one copy — the dog is healthy but can pass the mutation to 50% of offspring. At Risk means two copies — the dog may develop the disease. DNA Clear is not a blanket health guarantee — it applies specifically to the tested mutations. Always breed Carriers to Clear dogs, never to other Carriers, for any condition with serious health consequences.