Dogs, like humans, can catch Lyme, ehrlichia, and rocky mountain spotted fever. Your mileage may vary of course, depending on where you live. I've also been informed by the vet office that ticks removed promptly present less risk of infection. Apparently after the tick has been feeding for some time, it can regurgitate into the bite area and it is this that is really the vector for disease transmission.
Also from a post a couple up, ticks respond to motion, heat and carbon dioxide.