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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 Chihuahua we have compiled 1 mandatory and 13 recommended health tests, drawn from breed-club regulations, the University of PEI (CIDD), and OMIA — weighted by severity and heritability.
What this grade means
Although Chihuahuas can reach a very old age, the breed struggles with typical issues associated with extreme miniaturization. Painful patellar luxation and tracheal collapse, which can lead to severe respiratory distress, occur particularly frequently. The risk of hydrocephalus is also increased due to the shape of the skull, which is why prospective puppy buyers should carefully inquire about the health status of the parent dogs.
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 Chihuahua we track 1 mandatory tests plus 13 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 13 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
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
Corneal dystrophy(CD)
Augen und Sehvermögen
Corneal dystrophy is an inherited eye disorder where abnormal, opaque materials like fats or calcium build up in the cornea, which is the clear outer layer of the eye. This accumulation typically affects both eyes and is non-inflammatory, meaning it does not cause immediate swelling or redness. Over time, these deposits can disrupt the smooth surface of the eye.
Augen · Passing: CLEAR
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
Cryptorchidism
Fortpflanzung
Cryptorchidism is a developmental condition of the male reproductive system where one or both testicles fail to descend normally into the scrotum. Instead, the undescended testicle remains trapped inside the abdomen or in the groin area. This failure to descend is a physical development issue rather than an active illness, but it alters how the reproductive organs develop.
Physisch · Passing: CARRIER
Color Dilution Alopecia (CDA)(CDA)
Haut und Fell
Color Dilution Alopecia is a genetic skin disorder that affects dogs with diluted coat colors, such as blue, fawn, or lilac. It is caused by an abnormal distribution of pigment within the hair shafts, which makes the hair brittle and prone to breaking. This structural weakness leads to progressive hair loss and leaves the skin more vulnerable to irritation.
Haut · Passing: CARRIER
Demodicosis / Demodectic mange
Haut und Fell
Demodicosis is a skin disease caused by an overgrowth of microscopic Demodex mites that naturally live inside a dog's hair follicles. While these mites are normally harmless, an inherited or acquired weakness in the immune system can allow them to multiply uncontrollably. This overgrowth leads to inflammation and damage to the skin barrier.
Haut · Passing: CARRIER
Pattern baldness
Haut und Fell
Pattern baldness is a cosmetic, genetically influenced condition affecting the skin and coat. It occurs when hair follicles gradually shrink over time, leading to localized hair loss. Because there is no underlying inflammation or infection, the skin itself remains healthy and unaffected.
Haut
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
Patent ductus arteriosus (PDA)(PDA)
Herz
Patent ductus arteriosus is a congenital heart defect where a normal fetal blood vessel connecting the aorta and the pulmonary artery fails to close shortly after birth. This failure allows blood to continuously recirculate through the lungs instead of flowing to the rest of the body, putting severe, permanent strain on the heart muscle. Over time, this volume overload causes the left side of the heart to enlarge and weaken.
Ultraschall · Passing: NORMAL
Pulmonary stenosis(PS)
Herz
Pulmonary stenosis is a congenital heart defect characterized by a narrowing of the pulmonary valve or the outflow tract leading from the heart to the lungs. This narrowing restricts blood flow, forcing the right side of the heart to work much harder to pump blood. Over time, this constant strain can lead to thickening of the heart muscle and potential heart failure.
Passing: NORMAL
Chiari-like malformation (CM) and syringomyelia (SM)(CM/SM)
Nervensystem
Chiari-like malformation is a structural neurological condition where the back of the skull is too small for the brain, forcing the lower part of the brain into the spinal canal. This displacement blocks the normal flow of cerebrospinal fluid, the protective liquid surrounding the brain and spine. Over time, the blocked fluid builds up and forms painful, fluid-filled cavities called syrinxes within the spinal cord, a secondary condition known as syringomyelia.
Roentgen · Passing: A
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
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 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 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