What “Hereditary Clear” means — and when it stops

“Hereditary Clear” is not a test result. No laboratory has looked at that dog for that condition: it is a conclusion drawn from its parents. This page explains where it comes from, where it breaks, and how to check it before you rely on it. For screening schemes and DNA panels in general, start with health testing explained.

The results, for a simple recessive test

Many DNA tests on UK breed panels look for a single variant that causes a condition only when a dog inherits two copies of it, one from each parent. For a test like that, the Royal Kennel Club records these results.

• Clear. Tested, with no copies of the variant. The dog can only pass a normal copy to its puppies.
• Carrier. Tested, with one copy. It is highly unlikely to develop the condition, and each puppy has an even chance of inheriting either copy.
• Affected. Tested, with two copies. It is likely to develop the condition, and it passes one copy of the variant to every puppy.
• Hereditary Clear. Not tested. Recorded clear because of its parents.
• Hereditary carrier or affected. Rare. Where an untested puppy’s parents fix its result another way — one clear and one affected parent, or two affected parents — the Royal Kennel Club can record that as a hereditary status too.

How a dog becomes hereditary clear

The Royal Kennel Club’s registration system assigns the status to a puppy when both parents are known to be clear for the same autosomal recessive condition, either because each was DNA tested clear or because each is hereditary clear itself.

A clear parent has no copy of the variant to give, so two clear parents can only produce clear puppies. Because a hereditary clear parent counts as clear, the status can pass down a line for several generations without any dog in between being tested.

That is also its weakness. Every link depends on the original laboratory result and on the parentage recorded at every registration since. The Royal Kennel Club names laboratory failures, pedigree errors and wrongly recorded parentage as causes, and an error made once is inherited by every dog below it.

The Royal Kennel Club’s own research modelled this. In simulations with a modest rate of wrongly recorded parentage, for a variant making up one in five copies of the gene in a breed, more than one in twenty hereditary clear assignments were false once the status had been handed down for six generations. The more common the variant, the faster the errors built up.

When it stops

The chain stops the moment either parent is not clear or hereditary clear for that test. A puppy with a carrier, affected or untested parent cannot be hereditary clear, however good the rest of its pedigree. And any hereditary clear dog can simply be tested, which replaces an inference with a laboratory result for that dog.

What the chain does not currently have is a fixed generation limit. In 2019 the Royal Kennel Club announced that from January 2022 it would limit hereditary clear status to two generations, unless the line was verified by DNA parentage profiling. It postponed that to January 2023, then in July 2022 paused it because of technical challenges, saying its existing policy would remain for the foreseeable future — while adding that it still plans to bring the limit in and will say when. We found no later announcement bringing it into force. “Limited to two generations since 2022”, which you will still see repeated, describes a plan rather than a rule.

“Clear by parentage” is an American term

“Clear by parentage”, or CBP, is the status used by the Orthopedic Foundation for Animals in the United States, and its rules are stricter: both parents tested clear, all three dogs DNA profiled at the same laboratory with the parentage confirmed, first-generation puppies only, and direct mutation tests only.

In the UK the official status is the Royal Kennel Club’s hereditary clear, assigned from the parentage recorded at registration. Under the paused change, DNA parentage profiling would have been the way to keep the status beyond two generations. If a UK advert says “clear by parentage”, ask whether that is a status the Royal Kennel Club has recorded or the breeder’s own reasoning from the parents’ certificates. Both can be right. Only one is on the record.

What each pairing can produce

For a single autosomal recessive test, these are averages per puppy, not promises about a litter. A clear-to-carrier litter of six can hold any mix of clears and carriers, just as six coin tosses rarely land three and three.

A hereditary clear parent counts as clear here, on the assumption explained above. The Royal Kennel Club’s advice is that a mating which may produce affected puppies should never knowingly be carried out.

Why a carrier can still be the right stud

Take a hypothetical carrier stud with good hips, sound temperament and a pedigree that adds something the breed is short of. Mated to a tested clear bitch, he cannot produce a puppy affected by that condition. On average half his puppies will be carriers, so any puppy that may be a carrier should be tested before it is bred from — including by its new owners. The Royal Kennel Club suggests an endorsement or a clause in the puppy contract to make sure of that, and warns against overusing any one carrier.

The Royal Kennel Club’s advice is that carriers used responsibly are an important part of a breeding plan, because breeding only from clear dogs can cut genetic diversity and raise inbreeding. Its 2024 announcement on DNA control schemes encourages the use of carriers in a combination that will not produce affected puppies. A carrier result is a reason to choose the mate carefully, not a reason to rule the dog out.

What hereditary clear does not tell you

• It is one test at a time. A dog hereditary clear for prcd-PRA has no status at all for the other tests on its breed’s panel unless each was recorded separately. Check the whole panel — health tests by breed lists the tests the Royal Kennel Club Health Standard sets out for each breed.
• It only exists where a DNA test exists. A condition with no DNA test has no clear, carrier or hereditary result to inherit.
• It does not cover complex conditions. Hip dysplasia is polygenic, influenced by many genes and by environment, which is why it is screened by X-ray scoring rather than a single DNA result. See hip and elbow scores explained.
• It covers one variant, not the whole disease. Progressive retinal atrophy, for example, has several genetic forms, and not all of the variants that cause it are known. A dog clear for one form can still develop another, which is one reason eye examinations still matter alongside DNA tests.
• Not every test is a simple recessive. The Royal Kennel Club’s breeding advice above is for simple recessives: it gives separate advice for dominant, X-linked and risk-based tests, and warns that linkage tests may not be definitive. For an X-linked condition, a carrier bitch mated to a clear dog can produce affected sons. Check how the specific condition is inherited with the testing laboratory.

Check it yourself on the Health Test Results Finder

The Royal Kennel Club’s Health Test Results Finder is free and open to anyone. It shows the DNA and screening results the Royal Kennel Club has recorded for its registered dogs.

1. Get the dog’s registered name, or its registration number, exactly as it appears on the registration certificate. A pet name will not find it.
2. Search for it on the finder, then click the dog’s name to open its profile.
3. Find the condition you care about in the DNA results, and note whether the dog was tested itself or holds a hereditary status.
4. If it is hereditary clear, look up the sire and dam by their registered names from the pedigree, then their parents, until you reach a dog that was tested. That tells you which generation you are relying on.
5. If nothing is shown, ask for the certificate. The Royal Kennel Club’s records may not include all the testing a dog has had, so an empty record is not a finding.

The Royal Kennel Club records results only from its approved laboratories, and only from a certificate carrying the dog’s microchip or tattoo number with its registered name or number. It also notes that a result’s accuracy depends on the right sample being submitted and the laboratory following its procedures.

How Breed Right shows it

Breed Right stores a DNA result as one of four values (Clear, Hereditary Clear, Carrier, Affected), so a hereditary clear is never rounded up into a plain Clear. Every health result a visitor sees is marked “Verified”: a named member of our team has checked it against the Royal Kennel Club’s public records. A result nobody has checked yet is not shown to visitors at all.

Our check does not retest the dog, so a hereditary clear we have checked is still a hereditary clear: an inference the Royal Kennel Club recorded, not a laboratory result for that dog. Nothing on a listing is a health guarantee. How verification works sets out exactly what our check covers.

Results marked Verified were checked by us against the Royal Kennel Club’s public records on the date shown. Results we have not yet checked are not shown to visitors. The Royal Kennel Club’s public records may not include all screening a dog has had.