Requested Post #2-Titer testing

Titer testing is not a one size fits all answer.  It really depends on the particular disease and vaccine in question. The only titer tests that are "reliably" available for determination if vaccinating is needed are Distemper, Parvo, and Hepatitis.  A titer considered protective more than likely means this animal is protected against these diseases.  Here's the catch though, a titer below the cutoff determined by the lab or even a titer of zero does not mean the dog isn't protected.  Titer tests are checking only antibodies, but after vaccination a dog has the ability to mount an immune response to a disease with something called cell-mediated immunity as well as lymphocytes and other memory cells.  So, high titer most likely indicates protection, low titer in a previously adequately vaccinated dog, also probably protected.  Challenge studies show vaccines for these disease are good for at least 3 years.  Bottom line, usefulness of titer testing depends on what your goal is and what kind of info you are hoping to gain while balancing that with the cost of the testing.

Parainfluenza is often a part of the combo vaccine that includes the above three diseases.  There is no titer test for this but immunity seems to be of a similar duration.  It's also not a highly dangerous disease.

Titers for Lyme, Bordetella, and Lepto are unreliable in predicting adequate protection and these vaccines typically don't confer long term immunity like the others do. 

The most common test done for rabies titer testing is the FAVN test which is mainly used to export dogs to rabies free countries.  This test actually measures immune response to the vaccine and not necessarily a level of immunity considered protective to a challenge.  However, during licensing for rabies vaccines many dogs failed to develop a high titer but still survived a challenge.  So an acceptable FAVN number by default likely correlates to protective immunity. However, this test is expensive, and in most jurisdictions does not legally replace an actual vaccine.  This means in a bite case or legal dispute a titer test without a current vaccine is going to put you at a disadvantage when it comes to what happens to your dog.  Because this is a human health concern the only real excuse for not getting the vaccine is if your dog has certain medical conditions or has had severe reactions to the vaccine.  These rare cases can be discussed with your veterinary health care team.