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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 Rat Terrier we have compiled 3 mandatory and 5 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 Rat Terrier is considered an exceptionally robust and healthy breed with a high life expectancy. Nevertheless, prospective buyers should be aware of typical concerns such as Primary Lens Luxation (PLL), patellar luxation, and hip dysplasia (HD), which can occur in isolated cases. Since there are hardly any severe breed-specific defects, the genetic risk is refreshingly low.
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 Rat Terrier we track 3 mandatory tests plus 5 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 5 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: CLEAR
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
Deafness
Nervensystem
Deafness is a partial or complete loss of hearing that affects the nervous system and auditory pathways. It is often hereditary and frequently linked to specific coat pigmentation genes, such as the merle or piebald genes, which can affect the development of the inner ear. This genetic form of deafness results from a lack of pigment cells in the inner ear, leading to the degeneration of vital sensory cells.
Hoeren · Passing: Normal
Degenerative Myelopathy(DM)
Nervensystem
Degenerative Myelopathy is a progressive disease of the spinal cord where the protective sheath around the nerves slowly breaks down. This deterioration disrupts the vital communication signals between the brain and the muscles of the hind limbs. Over time, this lack of signal transmission leads to a complete loss of muscle control in the back legs.
DNA · Passing: CARRIER
Familial goitre(CHG)
Stoffwechsel
Familial goitre is an inherited disorder of the endocrine system where the thyroid gland is unable to produce essential thyroid hormones. This genetic defect causes the thyroid gland in the neck to enlarge significantly as it tries to compensate for the hormone deficiency. Without immediate treatment, this lack of hormones severely disrupts normal growth and body functions.
Passing: CARRIER
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 — Lens luxation
Both parents must be Clear or Carrier 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.
3 tests are currently mandatory under the relevant breed-club regulations. The most common are Lens luxation (PLL), Hip dysplasia (HD), Patellar Luxation (PL). 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