Fully health tested is a phrase, not a comparison. To judge a breeder properly you need two lists side by side: the tests the parents of this litter actually had, with results you can see, and the tests the breed club recommends for this breed. Where the lists match, you have evidence. Where they differ, you have questions to ask before a puppy's face makes the decision for you.
Build the breed club list first, before you visit
Breed clubs and national kennel bodies publish the conditions that matter most in each breed, usually because those conditions are inherited, painful or expensive: hip and elbow scoring in many larger breeds, eye examinations in breeds prone to inherited eye disease, heart testing where murmurs and valve problems run in lines, and DNA tests for specific known mutations. Write the recommended list for your breed down in full, including how often each test should repeat, because an eye test from several litters ago does not cover this breeding.
Ask the breeder for results, not reassurance
A careful breeder will produce documents without being offended: scoring certificates, laboratory reports or entries you can verify against the relevant scheme, for both the mother and the father. Note the exact result, not just that a test happened, because a hip score is a number with a breed average to compare it against, and a DNA result can mean clear, carrier or affected, with different implications for the puppies depending on the other parent's status. Be alert to substitutions: a general vet check is not a scored test, a DNA panel covering dozens of conditions may still omit the one that matters in this breed, and testing grandparents does not replace testing the actual parents.
Read the gaps and decide what they mean for this litter
When a recommended test is missing, ask why, and weigh the answer rather than the tone. Sometimes there is a sensible reason: a test newly recommended that the breeding predates, or a scheme unavailable in the breeder's country, with alternative evidence offered instead. Sometimes the answer reveals that the breeder simply does not test for the breed's most serious inherited condition, which is the single most useful thing you can learn before falling for the litter. Remember that good results lower risk rather than removing it: clear parents can still produce an affected puppy with conditions that are inherited in complex ways, which is exactly why scores are compared against breed averages instead of read as guarantees. What you are buying with proper testing is a breeder who has spent money to reduce suffering in the breed and can prove it on paper.
Check the paperwork trail you will inherit
Before committing, establish exactly what documentation comes home with the puppy: copies of both parents' results, the puppy's own microchip and first examination record, vaccination and worming history, and any contract terms about health. Check that the names and details match the dogs you were told about, because paperwork errors surface years later when a vet or insurer needs the history.
Keeping the evidence useful after you buy
The comparison you did before choosing only keeps its value if the documents stay findable, because a vet planning treatment, a new practice taking over care, or you considering insurance questions years later will all want the parents' results and the puppy's early records. KinsLe Pet Passport holds those papers together with your dog's own growing record in one portable packet, so the health evidence you checked so carefully before falling for the litter is at hand for every decision that follows.