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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 Mastiff we have compiled 3 mandatory and 7 recommended health tests, drawn from breed-club regulations, the University of PEI (CIDD), and OMIA — weighted by severity and heritability.
What this grade means
As a true giant breed, the Mastiff faces significant challenges due to the immense strain on its skeletal system. Hip dysplasia (HD) and elbow dysplasia (ED) are the most well-known vulnerabilities, which can be severely exacerbated by the extreme body weight of these dogs. Prospective buyers should be aware that, despite mandatory health tests, the risk of serious, chronic joint issues remains above average for this breed.
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 Mastiff we track 3 mandatory tests plus 7 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 7 additional clinically recommended screenings that reduce risk in this breed.
In addition to mandatory tests:
Ectropion / Entropion
Augen
These are structural eyelid abnormalities affecting a dog's eyes. In cases of entropion, the eyelid rolls inward, causing the eyelashes or fur to rub painfully against the surface of the eyeball. In ectropion, the eyelid sags or rolls outward, leaving the sensitive inner lining of the eye exposed and unprotected.
Passing: Unaffected
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
Retinal Dysplasia(RD)
Augen
Retinal dysplasia is a congenital condition affecting the eyes, where the retina (the light-sensitive tissue at the back of the eye) does not develop properly during growth in the womb. This abnormal development leads to structural defects like folds or gaps in the retinal layers. Because the retina is responsible for sending visual signals to the brain, these imperfections can impair normal vision.
Augen · Passing: Unaffected
Exposure keratopathy syndrome (exophthalmos, lagophthalmos, and/or macroblepharon)(EKS)
Augen und Sehvermögen
This condition involves chronic damage to the cornea, which is the clear protective outer layer of the eye. It occurs when the eyelids cannot fully close to moisten the eye, often due to protruding eyeballs, incomplete eyelid closure, or an abnormally large eyelid opening. Without proper moisture, the delicate surface of the eye becomes dry, inflamed, and vulnerable to injury.
Augen · Passing: Unaffected
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: Unaffected
Persistent pupillary membranes (PPM)(PPM)
Augen und Sehvermögen
Persistent pupillary membranes (PPM) occur when tiny blood vessels that nourish the eye's lens before birth fail to break down and disappear as they normally should. This leaves behind delicate strands of tissue that stretch across the iris, which is the colored part of the eye, and the pupil. In some cases, these strands can attach to the cornea, the clear outer layer of the eye, or the lens.
Augen · Passing: Unaffected
Cystinuria(Cyst-1a)
Nieren
Cystinuria is an inherited metabolic disorder affecting the kidneys, where the body fails to reabsorb an amino acid called cystine. Instead of being filtered back into the bloodstream, cystine builds up in the urine. Over time, this high concentration causes the amino acid to crystallize, forming painful stones in the bladder and urinary tract.
Koerperfluessigkeiten · Passing: Clear or 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 — Elbow Dysplasia
Both parents must be Grade 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.
3 tests are currently mandatory under the relevant breed-club regulations. The most common are Elbow Dysplasia (ED), Hip dysplasia (HD), Pulmonary stenosis (PS). 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