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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 Cairn Terrier we have compiled 14 mandatory and 11 recommended health tests, drawn from breed-club regulations, the University of PEI (CIDD), and OMIA — weighted by severity and heritability.
What this grade means
While the Cairn Terrier is a robust companion in everyday life, it carries an above-average genetic burden with nine registered mandatory health tests. The eyes are particularly vulnerable to conditions such as Progressive Retinal Atrophy (PRA) and cataracts, which can lead to blindness in the worst-case scenario. Additionally, when purchasing a puppy, you should specifically check for kneecap stability (patellar luxation) to avoid future joint problems.
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 Cairn Terrier we track 14 mandatory tests plus 11 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 11 additional clinically recommended screenings that reduce risk in this breed.
In addition to mandatory tests:
Progressive Retinal Atrophy (PRA)(PRA)
Augen
Progressive Retinal Atrophy (PRA) is an inherited eye disease that affects the retina, which is the light-sensitive layer of tissue at the back of the eye. In this condition, the specialized cells responsible for detecting light, known as photoreceptors, gradually degenerate and die. Because these cells cannot recover or be replaced, the disease slowly but inevitably leads to complete blindness.
Passing: CARRIER
Primary Open-Angle Glaucoma(POAG)
Augen und Sehvermögen
Primary open-angle glaucoma is an inherited eye disease where the natural fluid inside the eye cannot drain properly. This fluid buildup causes a gradual increase in pressure within the eyeball, which eventually damages the optic nerve, the connection between the eye and the brain. Without management, this pressure leads to permanent blindness.
Augen · Passing: CLEAR
Cataract(HC)
Augen und Sehvermögen
A cataract is a progressive clouding of the lens inside the dog's eye, which is the clear structure that focuses light onto the retina at the back of the eye. When the lens becomes cloudy or opaque, it blocks light from entering, gradually impairing the dog's vision. If left untreated, this condition can eventually lead to complete blindness in the affected eye.
Augen · Passing: CLEAR
Craniomandibular osteopathy ("lion jaw")(CMO)
Bewegungsapparat
Craniomandibular osteopathy, often called "lion jaw," is a temporary bone disease affecting the skull and jaw of growing dogs. It causes abnormal, non-cancerous bone growth on the lower jawbone and surrounding joints. This swelling is painful and can restrict normal movement of the jaw during the puppy's development.
Roentgen · Passing: Clear or Carrier
Legg-Calvé-Perthes disease(LCPD)
Bewegungsapparat
Legg-Calvé-Perthes disease is a serious orthopedic condition affecting the hip joint, primarily in small breed dogs. It occurs when the blood supply to the head of the thigh bone, known as the femur, is spontaneously disrupted. Without blood, this bone tissue dies and collapses, leading to severe joint inflammation and pain.
Roentgen · Passing: A
Mitral valve dysplasia(MVD)
Herz
Mitral valve dysplasia is a congenital heart defect where the mitral valve, which acts as a one-way gate on the left side of the heart, does not form correctly. This malformation prevents the valve from closing tightly, allowing blood to leak backward instead of pumping efficiently to the body. Over time, this leakage strains the heart muscle, which can lead to heart enlargement and eventual heart failure.
Ultraschall · Passing: NORMAL
Hemophilia
Herz und Kreislauf
Hemophilia is an inherited blood clotting disorder affecting the circulatory system, where the body lacks specific proteins needed for coagulation, which is the process of blood clotting. Because the blood cannot clot properly, even minor injuries can lead to prolonged internal or external bleeding. This condition is inherited through an X-linked genetic trait, meaning it primarily affects male dogs.
Koerperfluessigkeiten · Passing: CLEAR
Pyruvate kinase (PK) deficiency(PKD)
Herz und Kreislauf
Pyruvate kinase (PK) deficiency is an inherited metabolic disorder affecting red blood cells, which lack a vital enzyme needed to produce energy. Without this enzyme, the red blood cells break down prematurely, leading to a severe shortage of oxygen-carrying cells, a condition known as chronic anemia. Over time, this constant cell destruction can cause secondary damage to organs like the liver and bone marrow.
DNA · Passing: CARRIER
Globoid cell leukodystrophy (galactocerebrosidosis)(GCL)
Nervensystem
Globoid cell leukodystrophy is an inherited metabolic disorder affecting the nervous system, caused by a deficiency in an essential enzyme. This deficiency leads to the buildup of harmful substances that destroy myelin, which is the protective sheath surrounding nerve fibers in the brain and spinal cord. Without this protective covering, the nerves cannot transmit signals properly, resulting in progressive neurological decline.
DNA · Passing: CARRIER
Hydrocephalus
Nervensystem
Hydrocephalus is a neurological condition affecting the brain and nervous system, commonly referred to as water on the brain. It occurs when cerebrospinal fluid, the natural protective liquid surrounding the brain, builds up abnormally inside the brain's cavities, known as ventricles. This accumulation creates harmful pressure on the surrounding brain tissue, which can impair normal brain function.
Roentgen · Passing: A
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
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 0 oder 1 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.
14 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