I am going to address health testing in the Doberman, Let's start with Dilated cardio myopathy;there is a lot more to monitoring DCM in the Doberman than slapping a holter monitor on a breeding pair.  It proves one thing; that at the time of the breeding neither dog had it.  Does it mean that they will not get it?  No it does not.  Does it mean the puppies will not get it? - No, it does not.  Beware of the breeder that had their dog OFA certified 1 time and tells you the dog does not have cardio. I personally know of one such case where a "top" breeder did this and sold a puppy with a "heart murmur" telling the new owner it would out grow it.  It was DCM and the dog died at 4 years old. The average age a Doberman gets DCM is 7.5 years; that is not someone's opinion, it is a fact.  Currently 50% of All Dobermans will develop cardio.  It is not known what causes it.   Conscientious breeders that really want to make a difference participate in LONG term programs; as we are at the University of Guelph.  All of our dogs, current breeders, retired breeders and even some pups from past and current litters receive a holter annually for the life of the dog.  This is the only way we can help in finding a way to halt this devastating disease.  Follow these links to find out the scientific FACTS about DCM.
http://www.ovc.uoguelph.ca/clin/faculty/mogrady/holter/holterinfo.htm

http://www.ovc.uoguelph.ca/clin/faculty/mogrady/holter/holterfaqs.htm

Some common health tests for the Doberman at this time are Vwd testing( preferably by vet gen,)
A clear dog is a clear dog for life.  OFA certification of hips; which is done no earlier than 2 years of age.  There is also the penn hip check.  These are finite tests to a degree, poor diet or injury can obviously change the results of hips.  We have had this testing done on our current active breeders. Keep in mind the Doberman is #116 on the OFA list and 93% of them are Normal http://www.offa.org/stats.html#breed   This has pretty much been eliminated by good breeding.
The thyroid panel is a test in which the results can be easily manipulated and again does not guarantee your dog will not get thyroidism. Here is an article that should shock you a; "show breeder" trick Is Hypothyroidism Really the Leading Canine Genetic Disease?
When I purchase a Doberman I want to know how long this person has been breeding,
I want to meet and see both parents and evaluate them my self. Two healthy genetically sound Dobermans yield genetically sound puppies. How many dogs are alive from past litters?  How old are they?  How many dogs have they bred that live 8+ years?  What health issues have there been?  They should be able to provide you with this info; any breeder that cares offers all his clients to stay in touch and encourages them to do so.  We even send out surveys to help in obtaining this data.
You should get a  written warranty stating specifically what is covered.  Look around and see how many self proclaimed top breeders citing the merits of their testing give you a 1 or 2 year warranty or less on your pup.(some make no reference to a warranty) That means nothing, obviously they know something they do not want you to know; as previously discussed you can not even OFA certify for hips till they are 2 years of age.  Many other genetic abnormalities will not even begin to surface till 2-4 years. I would not buy a dog with less than a 4 year warranty, look around and see how scarce this is.  To some; titles are more important than health and longevity.  I know of a few sites that currently still use pictures of Dobermans that have died, insinuating they are alive and well.  Testing is a tool; to be used along with knowing the lineage of your dogs their current state of health and that of their offspring.