I recently went to a lecture on Lyme disease…freaked me out...and after that I was at my vet and asked about putting Ruby and Brando on Frontline. My vet told me to not bother with it. I live in an area with a lot of ticks but she said that because Frontline isn't completely effective and because she knows of some dogs that got Lyme using Frontline, I'd do just as well to just check the pups over thoroughly when they come in from outside and not use Frontline. She wasn't against Frontline, but just felt that with Ruby & Brando's short coats, a visual check would be the most effective method of dealing with ticks.
Maybe once a week I do find a tick on Brando...haven't found one on Ruby yet, but I'm vigilant and know that I've found it within an hour or two of one climbing on him. With one exception they have only been dog ticks, luckily...one was definitely a deer tick though. But even with a deer tick you usually have 24 hours before you need to worry.
Nina, the really small ones may be deer ticks (that's what the small ones are here)...those are the ones you need to worry about.