Loading health guide
Health Testing Guide
Which tests are mandatory, how to spot responsible breeders — and what it costs when things go wrong.
For the Norwich Terrier we have compiled 12 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 Norwich Terrier receives a grade of C because the breed is prone to Upper Airway Syndrome (UAS), which can cause serious respiratory difficulties. Patellar luxation, where the kneecap painfully slips out of place, is also a known issue in these small dogs. Prospective buyers should ensure that the parents have been officially cleared of these conditions to minimize the risk of future breathing problems or joint issues.
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 Norwich Terrier we track 12 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:
Brachycephalic obstructive airway syndrome (BOAS)(BOAS)
Atmung
Brachycephalic obstructive airway syndrome (BOAS) is a severe respiratory condition affecting short-muzzled dog breeds, where the physical shortening of the skull leaves insufficient space for the upper airways. This structural compression forces tissues like the soft palate and nasal passages into a restricted area, significantly obstructing the flow of oxygen to the lungs. Over time, the increased effort required to breathe puts chronic strain on the dog's respiratory and cardiovascular systems.
Physisch · Passing: Grade C2 or better
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/Carrier
Portosystemic hepatic encephalopathy(PSS)
Stoffwechsel
This is a neurological condition caused by liver dysfunction, typically occurring when abnormal blood vessels bypass the liver. Because the liver cannot filter toxins from the bloodstream, these harmful substances build up and directly affect the brain. This lack of proper filtration leads to central nervous system dysfunction.
Passing: Normal bile acids
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 — Patellar Luxation
Both parents must be Grad 1 or better 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.
12 tests are currently mandatory under the relevant breed-club regulations. The most common are DNA-Identitätsnachweis, Ocular anomalies, Cone-rod dystrophy 3 (crd3) (crd3). 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