Hi,
I have no flea problems with my dogs, but... previously owned a Rottie which was a flea magnet - had 2 Jack Russels as well, never had a flea problem with them - and being white fleas show up on them very easily. So you need to consider that some dogs attract fleas more than others, same as some people will be covered by mozzie bites when the person next to them gets none! Also, I use a tea tree soap which is a natural insect repellant. Its also very good for doggy dandruff & odours. As my dogs are German Spitz, with long thick coats, they are thoroughly groomed with a scalp massager at least 3 times a week - as a kid I LOVED brushing my stuffed toys!!
anyway, seems to keep all fleas, ticks etc at bay. For the rottie I used a powder, it seemed most effective.
cheers
Kris