it is so dang complicated keeping breeds healthy. For instance, in my favorite breed we have some who are all about body structure..slot a fitting into slot b, and others who are all about the working ability and temperament. But really we need both.
I’ve had one mix that lived well into her teens and was smart and sociable. Not a good watch dog though. I had another that lived until 12,a bit neurotic but it might have been as much from being a stray as from genetics. She was sweet though. That is why I like these studies. How much is genetic, how much is experience?