Jeri
The foremost vet immunologists in the field disagree with you that titers "don't mean anything". On the contrary, studies have been conducted to prove correlation between both serological and live challenges for viral immunity and titers. There is certainly a correlation. A nice one, actually. The caveat is to remember that just because a titer is LOW or non-existent does NOT mean that immunity is gone (for an adult animal, with proof of past immunity) because of CMI. MLV vaccines for Parvo and Distemper provide sterilizing immunity if given properly and assuming that the dog's body mounted the appropriate immune response (verifiable by titer). Killed are, of course, more complicated in that they do not provide sterilizing immunity, but even there we are seeing the emergence of a verifiable titer in the case of Rabies for people, and the latest Rabies Challenge Study data is going to provide one specifically for dogs as well.