DC’s Improbable Science points out, in a letter from an ex-chiropractor:
Two practices are of particular concern in some chiropractic offices and in my view; these alone should be sufficient reason to prevent chiropractors from calling themselves “doctor”. The first is the systematic and deliberate erosion of a person’s confidence in the medical system. Many offices have anti medical literature in their libraries. Chiropractors are sometimes taught practices to subvert medical credibility. See http://chirobase.org/20PB/top7.html for an example.
The second is a subset of the first but is particularly damaging. It is active opposition to vaccination. At chiropractic school, I was taught anti-vaccination information in my paediatrics course. I have seen books written by chiropractors opposing vaccination and I have seen many offices with anti vaccination leaflets and books in abundance. Now I am all for informed choice but this type of material is rarely accurate or balanced. People are being encouraged not to vaccinate their children by professionals who they believe to be a reliable and prestigious source of information.