I agree with them, over vaccination is a problem. There is compelling evidence which show over vaccination can cause things such as autoimmune diseases, allergies and even cancer!
You want to make sure you dog is vaccinated according to what you dog needs. You need to make sure your dog has enough anti bodies to protect against Rabies, Distemper, Parvo, Lepto and all the diseases we vaccinate for. Each of these diseases are very real and still do pose a threat.
One of the best ways to make certain you are not over vaccinating or under vaccinating your dog is to have your vet do a titer on your dog.
What is a titer? Titers are a blood test that measures the actual level of protection your dog’s immune systems has against certain diseases.
If the antibody levels measure high enough, then your dog is protected against that particular disease, which means you do not need to get a booster. Yes Titers are more expensive, it is a price I am willing to pay to have the peace of mind knowing whether I need to vaccinate my dogs or not.