16/04/2026
An article I wrote for Dogs New Zealand Canine Health & Welfare Committee, published in the March issue of Dog World to counter claims by some 'breeders' that health testing is not necessary
“But we know our lines are clear”: why health testing still matters
One of the most common statements we hear from long-standing pedigree dog breeders is: “We don’t need to health test — we know our lines are clear.” It is usually said with pride, and often reflects decades of careful breeding, detailed record-keeping, and deep familiarity with a particular breed or family of dogs.
As a committee, we acknowledge and respect that experience. Knowledge of one’s lines is a cornerstone of responsible breeding.
But modern canine genetics and the experience of kennel clubs internationally shows that knowing your lines and health testing are not alternatives. They are complementary. Health testing does not undermine experience; it strengthens it by confirming assumptions, identifying hidden risks, and protecting breeds from outcomes that even the most careful breeders cannot reliably predict.
The problem of “silent” hereditary disease:
A key limitation of relying solely on observation and pedigree knowledge is that many inherited conditions are not visible.
Autosomal recessive diseases provide a clear example. Conditions such as Lafora disease, certain forms of progressive retinal atrophy (PRA), and other DNA-testable disorders can be carried silently for generations. Carrier dogs are clinically normal. They show no signs of disease, perform well, and may come from lines with no known history of the condition. A breeder can quite genuinely believe their lines are “clear” right up until two carriers are unknowingly mated and affected puppies result.
This is not hypothetical. Overseas experience, and more recently New Zealand experience, has shown that conditions can emerge unexpectedly in well-established kennels with long breeding histories and no recent outcrosses. The issue is not poor breeding practice; it is the biological reality of recessive inheritance. Without DNA testing, carriers cannot be reliably identified.
Late-onset conditions: knowledge arrives too late
Other inherited diseases present a different challenge: they appear after breeding has already occurred. Conditions such as PRA or some cardiac disorders may not manifest until middle age or later. A dog may pass early screening, produce multiple litters, and only subsequently develop clinical disease. By the time the problem is recognised, its genetic influence may already be widespread.
Again, this is not a failure of breeder vigilance. It is a limitation of what can be seen without objective testing tools. The increasing availability of DNA tests for late-onset conditions exists precisely to address this gap.
The closed gene pool reality
Pedigree dog breeding operates within closed populations. This brings predictability of type and temperament, but it also means that once a mutation enters a breed, or a popular family within a breed, it can persist quietly for many years. The widespread use of successful dogs can unintentionally amplify the frequency of rare mutations, even in kennels with excellent records and intentions.
The emergence of a condition such as Lafora in a long-established line should never be viewed as a moral failing. It is a population genetics issue, and it is exactly why modern health management relies on data, not assumptions.
What international practice tells us
Comparable kennel clubs overseas have responded to these realities by embedding health testing into routine breeding practice.
In the United Kingdom, the Kennel Club and British Veterinary Association operate long-standing screening schemes for hips, elbows, eyes, and other conditions, with results used to guide breeding decisions at a population level.
In the United States, the Orthopedic Foundation for Animals (OFA) and the Canine Health Information Center (CHIC) work with breed clubs to define breed-specific testing recommendations. Public recording of results is encouraged, recognising that transparency supports better decisions without unnecessarily restricting breeding options.
In Scandinavia, particularly Sweden, structured health programmes and centralised databases have been in place for decades. Mandatory or strongly recommended testing is normal, and breed health strategies are adjusted as new information becomes available.
Across these systems, the underlying principle is consistent: responsible breeding combines experience with objective evidence.
Health testing is about informed mating — not exclusion
A frequent concern is that health testing will force breeders to remove large numbers of dogs from breeding programmes. Modern genetic management does not support that approach.
For most recessive conditions the accepted international strategy is not to eliminate all carriers immediately. Instead, breeders are encouraged to plan matings so that affected puppies are not produced, typically by ensuring that at least one parent is clear. This allows valuable dogs to remain in the gene pool while progressively reducing disease risk over time.
Similarly, phenotypic screening schemes enable breeders to select for improvement without narrowing genetic diversity to an unsustainable degree. Health testing, when interpreted correctly, is a decision-making tool, not a blunt instrument.
“We’ve never seen it” is not evidence it isn’t there
It is also important to recognise that some conditions are under-reported or misattributed. Vision loss may be blamed on age, seizures on unrelated causes, lameness on injury. Once puppies leave a kennel, breeders may not receive full information about later health outcomes.
Testing replaces uncertainty with clarity. It allows breeders to move from “we haven’t seen it” to “we have evidence.”
What this means for Dogs New Zealand breeders
As a committee, our objective is not to criticise past practices, but to support breeders in using the best tools now available. International experience shows that effective health programmes share common features:
• Testing that is breed-relevant and proportionate
• Clear guidance on interpreting results, particularly for carriers
• Use of results to guide mating decisions rather than exclude dogs unnecessarily
• Education and transparency that build confidence in pedigree breeding
Health testing does not imply that earlier generations were irresponsible. It reflects scientific progress and an ethical responsibility to act on new knowledge once it exists.
A shared responsibility for the future
For breeders who have always said, “We know our lines,” we invite a reframing of the purpose of health testing. Testing does not contradict that knowledge; it confirms it, strengthens it, and protects it.
In an environment of increasing public scrutiny, the credibility of pedigree dog breeding depends on transparency and demonstrable commitment to welfare. Overseas experience shows that when breeders adopt health testing thoughtfully and proportionately, breeds benefit — and so does public trust.
Health testing is not a lack of faith in our lines. It is an investment in their future.
Practical checklist for breeders
Before breeding, ask:
• ☐ What hereditary conditions are known or emerging in my breed?
• ☐ Are there DNA-testable recessive diseases (e.g. Lafora, PRA) relevant to my dogs?
• ☐ Are sire and dam tested before mating where practicable?
• ☐ Do I understand the implications of clear, carrier, and affected results?
• ☐ Have matings been planned to avoid producing affected puppies?
• ☐ Are results recorded and available to inform future breeding decisions?
• ☐ Can I clearly explain health testing outcomes to puppy buyers?
Good breeding decisions are informed decisions.
