there seems to be some confusion in your question .
you ask quoting you, usxmarine
"where you have a AKC registered dog with generations of traceable pedigrees it may not be necessary"
there is a DNA certification which verifies that the sire and dam are as recorded. A cheek swab is taken from
the sire and the dam , and the subject pup.
https://vetdnacenter.com/dna-tests/canine-dna-testing/
In your case if sire and dam had not been done - you would need the breeders' co-operation (if each parent is owned by different breeders).
for disease you can get a test for DM , (degenerative myelopathy) you need to get a different test kit from that lab.
this test is controversial . Statistics gathered for GSD DM are speculative because without a specific test (head/brain)
of the deceased there is no accurate data.
the other controversy involves the nature of DM and whether DM in "this" breed is the same as in other breeds.
the ideal is to always care for health --- as if --- preventive . This is applicable to dogs, and yourself .
for DM specifically provide neurodegenerative supportive anti inflammatory oils for one , true or real vitamin E ,
omega 3 , coconut oil , conjugated linoleic acid - CLA . The CLA is available from grass/pasture fed red meat .
research is showing benefits derived from coconut oil that delay and reverse alzheimer's .
Coconut oil by passes digestion . It is metabolized by the liver and sent to the brain, adrenal and thyroid .
It crosses the brain barrier .
most exciting is research into PUNIC acid - omega 5 , and MS multiple sclerosis . So far results using mouse models have been promising .
Safe for dogs ? I need to consult with my experts for an answer to this. Pomegranate can be eaten by dogs but the seeds are notoriously indigestible so may give stomach upset.
the last test is for determining main genetic group contributors to a dog of mixed breed ancestry .
I wouldn't spend any money on this .
when a person who worked on the canine genome , and is continuing with research , says it is difficult to determine
"breed" that says it all.
some people out of curiousity have done the "breed" ancestry test and have come up with near impossible combinations.
not because of physical difficulties with size or other , but for the fact that there may only be half a dozen of said breed in all of America - and they are accounted for. They weren't roaming the street looking for action.
Is your dog a GSD?
If so , then consider the line-up of usual suspects .