a little thing about the genetics (probably unnescesary for most of the people here)
A dwarf is homozygote for the dwarg gen. (two gens for dwarf one inherited from the mother and one inherited from the father)
A carrier is heterozygoot for the dwarg gen and is healthy him/herself. it has a healthy gen and a dwarf gen (one inherited from the father or the mother)
a healthy dog doesn't carrie the dwarf gen, this dog has two healthy gens.
A dwarf dies or is recognised as a dog you do not breed with
If you breed with two carriers, a qwart of al the puppies is going to be a dwarf (statisticly), 1/2 is going to be a carier again, and another 1/4 are going to be healty dogs.
So to validate the test you must test the dwarf or the parents, if you test the other pups it could be that you wil test the healthy pup and so this test cannot be validated.
if you breed a carries with a healthy dog (without the gen) only healthy (1/2) and carries(1/2) are going to be born.
So if this test can be used with our breed, you can stil breed with al the carriers if the other dog is healthy(doesn't carry the gen) so no new dwarf wil be born. So no dogs has to be ruled out as a breeding dog that is good because there aren't that many dogs so that we can be very picky