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Health Testing Guide
Which tests are mandatory, how to spot responsible breeders — and what it costs when things go wrong.
For the Sealyham Terrier we have compiled 1 mandatory and 3 recommended health tests, drawn from breed-club regulations, the University of PEI (CIDD), and OMIA — weighted by severity and heritability.
What this grade means
The Sealyham Terrier is rated B because it is generally a robust dog, even though there are few mandatory health tests anchored in the official breed standards. Buyers must take the initiative themselves and insist on proof of testing for Primary Lens Luxation (PLL), as well as screenings for intervertebral disc disease (IVDD) and congenital deafness. Without these voluntary screenings of the parent dogs, purchasing a puppy remains a health risk.
Every breed is susceptible to certain inherited conditions. Just like humans, dogs inherit predispositions from their parents. Responsible breeders screen their breeding dogs for these conditions and make informed mating decisions to reduce the risk passed on to puppies.
No — but it's the strongest tool we have. Diet, exercise, environment, and genetics all contribute to whether a dog develops a condition. When breeders use the right tests to identify risk in potential parents, the likelihood of many conditions appearing in the puppies drops significantly.
There's no one-size-fits-all here. For the Sealyham Terrier we track 1 mandatory tests plus 3 additional recommended ones. The specific tests and passing thresholds are detailed further below.
Keep in mind
Reliable screening tests still don't exist for many hereditary conditions, and tests for complex polygenic conditions are not always predictive of severity in the puppies. Even so, they're a powerful tool used by every responsible breeder.
There are two main types of health tests:
Screen the dog's DNA for known disease-causing mutations. Can be performed from puppyhood and give a binary result (clear / carrier / affected).
Clinical and imaging exams like X-ray, ultrasound, or ophthalmoscopy. They show how a predisposition actually manifests — usually only conclusive after 12–18 months.
We group breeding programs into three levels based on testing depth. Ask your breeder directly which level they meet.
A breeder at the Great level performs all mandatory tests plus 3 additional clinically recommended screenings that reduce risk in this breed.
In addition to mandatory tests:
Keratoconjunctivitis sicca (KCS) - "dry eye"(KCS)
Augen
Keratoconjunctivitis sicca (KCS), commonly known as dry eye, is a chronic disease of the ocular system where the tear glands fail to produce enough natural tears. Without this protective moisture, the cornea (the clear surface of the eye) and surrounding tissues become dry, inflamed, and highly susceptible to painful damage.
Augen · Passing: CLEAR
Lens luxation(PLL)
Augen und Sehvermögen
Lens luxation is an inherited eye disorder where the lens slips out of its normal position because the supporting fibers holding it in place weaken or break. When the lens shifts, it can block the natural drainage of fluid within the eye. This blockage causes a rapid, painful buildup of pressure called glaucoma, which can lead to permanent blindness if left untreated.
Augen · Passing: Clear or Carrier
Congenital deafness(CHSD)
Nervensystem
Congenital deafness is a hereditary hearing loss present from birth that affects the inner ear's sensory cells, preventing sound signals from reaching the brain. It is often linked to specific genetic variants, such as those associated with certain coat patterns like merle or piebald, or breed-specific conditions like Early Onset Adult Deafness (EOAD). This genetic defect causes the vital blood supply to the inner ear to fail, leading to the permanent degeneration of the hearing nerve cells.
Physisch · Passing: BILATERAL_HEARING
These levels are a comparison framework, not an official certification. They help compare breeding programs at a glance.
A complete checklist with every mandatory and recommended test plus identity and rearing questions — take it with you.
Open the full checklistFor breeders
Machine-readable mating rules, minimum ages, scoring schemes, and what's required for HonestDog verification — as a printable guide.
Example rule — Retinal Dysplasia
Both parents must be CLEAR or better.
We compile mandatory tests from official breed regulations and veterinary databases — and check every uploaded certificate for authenticity.
L1 = mandatory under breed-club regulations. L2 = recommended or clinically indicated. L3 = lower prevalence. Every assignment carries a source and confidence rating.
VDH breeding regulations, CIDD (University of PEI), OMIA (University of Sydney), curated veterinary input.
Uploaded certificates are AI-extracted and reviewed by our team for authenticity, date, and result.
1 tests are currently mandatory under the relevant breed-club regulations. The most common are Retinal Dysplasia (RD). Every test must be completed before mating, and the result must fall within the threshold defined by the regulation.
See breeders who have already uploaded their mandatory tests for verification.
View verified breeders