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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 Malchi (Maltese x Chihuahua) we have compiled 2 mandatory and 4 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 crossbreed between a Maltese and a Chihuahua, the Malchi suffers from a lack of controlled breeding structures, which means that essential preventative health screenings are often neglected. Hereditary issues such as patellar luxation (dislocated kneecaps) and tracheal collapse are particularly common. Furthermore, these toy breeds have an increased risk of heart conditions, such as mitral valve insufficiency.
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 Malchi (Maltese x Chihuahua) we track 2 mandatory tests plus 4 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 4 additional clinically recommended screenings that reduce risk in this breed.
In addition to mandatory tests:
Tracheal collapse(TC)
Atmung
Tracheal collapse is a progressive respiratory condition where the C-shaped cartilage rings that keep the windpipe (trachea) open begin to weaken and flatten. As these supportive rings lose their rigidity, the airway narrows, making it difficult for air to pass smoothly into the lungs. This mechanical failure of the respiratory tract leads to chronic irritation and breathing difficulties.
Roentgen · Passing: Normal / Unaffected
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
Myxomatous mitral valve disease(MMVD)
Herz und Kreislauf
Myxomatous valve degeneration is a chronic heart disease where the heart valves, most commonly the mitral valve, gradually thicken and lose their normal shape. This structural change prevents the valves from closing tightly, causing blood to leak backward through the heart chambers. Over time, this backflow forces the heart to work much harder, eventually leading to congestive heart failure.
Ultraschall · Passing: NORMAL
Glycogen storage disease type Ia(GSD Ia)
Stoffwechsel
Glycogen storage disease type Ia is an inherited metabolic disorder affecting the liver and kidneys. It is caused by a deficiency in a key enzyme needed to break down stored sugar, known as glycogen, into glucose for energy. Without this enzyme, glycogen builds up to damaging levels in these organs while the rest of the body suffers from a severe lack of fuel.
Passing: CLEAR
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 — Progressive Retinal Atrophy (PRA)
Both parents must be CLEAR 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.
2 tests are currently mandatory under the relevant breed-club regulations. The most common are Progressive Retinal Atrophy (PRA) (PRA), 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