Not really provable-my vet believes that the oldest breeds are healthiest-those that have not been crossbred to change their appearance, size etc-and that are not high on the popularity list-which invites over-breeding-such as what has happened to German Shepherds and other popular large breed dogs. That all produces a higher risk of health problems/defects and a shorter life for the dog. I think she is right-I prefer the larger working/guard breed dogs as companions, and I always purchase a puppy from an AKC recommended kennel-never an adult dog-so that they become part of the pack along with the cats and they are taught to recognize me as the alpha leader from day one, which greatly minimized the chance of attack and bites on family members-I haven’t owned a dog that was not on the “bad dog” list in many years-and I have never had a badly-behaved dog.
I had two German Shepherds-they died at 12 and 13 respectively and both had arthritis. Since they are longer lived, I chose a Chow Chow for my next dog-he died in his sleep at 17, having never had a serious problem-he just slowed down and stopped. I got my Siberian Husky from an AKC sled-and show kennel in WA, near the Canadian border-she stopped in her sleep nearly 2 years ago, having never had a problem at all-she was 4 months shy of 18. Long healthy lives for dogs that weighed 85 and 80 lbs respectively-both of those breeds are centuries old, and have not been tinkered with by breeders much-neither breed is terribly popular or in demand enough to have been overbred...
The only canine DNA projects that are worthwhile at this time are those that are being done for research. For example, there’s one now for Golden Retrievers that collects the DNA of participating Goldens as puppies and then follows their health and development over their lifetimes. The idea is to identify the genetic markers asociated with diseases (e.g., cancers) and other problems.