The first item on the Sealyham's health list is not a test

Most health requirements can be met by posting a cheek swab. You send it, you wait, you get a letter with a word on it, and the word goes on the listing. That is the shape of nearly everything we are building GenoVaq to verify, and it is a good shape: a claim, a document, a laboratory behind the document.

Then you read the Sealyham Terrier Club's health page and find something on the minimum list that does not fit the shape at all.

What the list actually says

The Club reproduces the Royal Kennel Club's Health Standard for the breed, which sorts screening into two tiers. Best practice for the Sealyham is eye testing under the BVA/KC/ISDS scheme. Good practice — described plainly as the minimum, for conditions where the evidence indicates a significant concern in the breed — contains two items.

One is a DNA test for primary lens luxation, in which the fibres holding the lens in place break down, the lens dislocates, and the dog is left with painful glaucoma and blindness. That is a swab, a laboratory, a letter.

The other, listed first, is: prioritising genetic diversity.

There is no laboratory for that. No breeder will ever receive a certificate reading "diversity: clear". It sits on a minimum-standards list next to a DNA test, and it is not a test at all. It is an instruction about how to think.

Why the breed earns that instruction

The Kennel Club's vulnerable native breeds table gives the Sealyham's last decade as 113 registrations in 2016, 167 in 2017, 107 in 2018, 131 in 2019, 153 in 2020, 184 in 2021, 138 in 2022, 136 in 2023, 100 in 2024 and 111 in 2025.

The ten-year average is 134. The vulnerable line is 300. The breed has not been within touching distance of it in the whole period, and the two lowest years of the decade — 100 and 111 — are the two most recent, which is the same unhappy shape we found in the Clumber Spaniel's figures yesterday, at roughly two-thirds of the Clumber's scale.

A hundred and eleven puppies is not a population in any comfortable sense. It is a few dozen litters. Every stud dog used is a visible fraction of the next generation, every popular sire is a structural event rather than a preference, and there is no anonymous middle of the distribution for a mistake to disappear into. That is the situation the Health Standard is describing when it puts diversity on the minimum list. The governing body has looked at the breed and concluded that the most significant health risk is not any one condition. It is the arithmetic.

This is the point we have made from the other direction in why rare breeds don't breed the carriers out: in a small population, the reflex to exclude every carrier of a recessive costs more diversity than the recessive ever would. Ranking diversity above the DNA test on the same list is the official version of that argument, and it is a braver piece of drafting than it looks. It tells a breeder that a mating can be entirely defensible on paper — both parents tested, both clear, every certificate in order — and still be the wrong mating.

What that asks of a breeder, and of us

A test result is a fact about one dog. Diversity is a fact about a decision, and it can only be assessed against the population the decision sits in: the coefficient of inbreeding for the proposed pairing, how often that sire has already been used, whether an unfashionable line is being quietly allowed to end. We have written before about what a coefficient of inbreeding actually tells you, and this is the case where it stops being an interesting number and starts being the health test.

The uncomfortable part is that none of it is legible to a buyer. A buyer can be handed a PLL certificate and understand it in five seconds. Nobody has ever been handed a document proving that a breeder declined a convenient mating to a much-used dog. The work that the Health Standard puts first is exactly the work that a listing, an advert or a photograph cannot show.

The Club's own puppy page is unusually honest about what fills that gap instead. It cites the Royal Kennel Club's 2023 research finding that almost half of owners said social media influenced their puppy-buying decision, that four in ten admitted buying a puppy because it was cute, and that 46 per cent bought because of the way the dog looked. Set that beside a breed averaging 134 registrations a year and the mechanism is not mysterious. Looks move populations. We have written about what popularity costs a breed; the Sealyham is the same lesson read backwards, a breed that was once fashionable enough to be everywhere and is now maintained by people who kept going after the fashion left.

There are three separate breed clubs in the United Kingdom for those hundred-odd puppies a year — the parent Club, the Breeders Association, whose front page is currently marking ninety-eight years, and the Midland club. It would be easy to call that fragmentation. On the evidence it looks more like three sets of volunteers, three committees, three show schedules and three points of contact, all still standing for a breed that the market stopped rewarding decades ago. A puppy co-ordinator answering a telephone number printed on a website is not a scalable system. It is, at this population size, the system.

The standard we have to meet

We are building a marketplace for verified breeding genetics, and the honest limit of verification is worth stating on our own pages rather than leaving for someone else to point out. We can verify a PLL result. We can show a coefficient of inbreeding, a stud's progeny record, the dates and the certificates, and we intend to — that is the standard set by the Clumber stud page and it is not ours to invent.

What we cannot issue is a badge for prioritising genetic diversity, and we should be suspicious of anyone who offers one. It is not a state a dog can be in. It is a decision, taken one mating at a time, usually against the breeder's own short-term convenience, and the only evidence of it is a pattern visible across years of a breed's records rather than anything printed under a photograph. The most a platform can honestly do is publish the numbers that make the pattern visible, and then get out of the way of the people reading them.

If you breed Sealyhams, sit on one of the clubs, or would rather we heard the current state of the breed from you than reconstructed it from published pages, the address is info@genovaq.co.uk.

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Sources

• Health — The Sealyham Terrier Club
• Finding a puppy — The Sealyham Terrier Club
• Sealyham Terrier Breeders Association
• Vulnerable native breeds — The Royal Kennel Club

— Rene