Here's a nice link from the CDC listing all sorts of things I can come down with, although EXTREMELY rare, due to having pets.
Animals: Dogs | CDC Healthy Pets Healthy People
They state "To best protect yourself from getting sick, thoroughly wash your hands with running water and soap after contact with dogs, dog saliva, or dog feces (stool)."
I cannot imagine washing my hands every time after I touched my dog. That's a bit over the top.