I seem to have lost the plot here. You wrote to your vet? Or? What am I missing?
Okay I've re read this three times. I think I finally figured out that your original question is based on a discussion you were having with someone elsewhere about blood work and dentals and a dog.
My two cents, regardless of age, no animal of mine would go under anesthesia without a full blood work up called a super chem at my vet. the super chem includes the T-4 and Free T-4, and CBC, plus all the other things. I think they use Antech.
But yes, most people opt for in house testing which gives a very basic look at kidneys and livers, maybe white and red blood cell?
A person has to have SOME trust in a vet. If you're all the time thinking the vet is out to screw you, it's either you with the problem (some people just have that attitude), or you need a new vet.
I use "you" in a general sense.