I heard that it was only the "blue" (original) one that worked and not the others?? Could it be the colorant?
We used the dawn because the kittens (at 4 weeks) were way too young to use a topical like advantage. We had to rebathe about 1 time a week (at least) and comb them to keep the fleas down until they were old enough to put advantage on them. It wasn't 100%, as we would still see fleas ocassionally, but it did get the majority of them.
I don't know if it kills the fleas outright or just paralyzes them temporarily...We didn't have any flea problems in the area where I washed the fleas down the sink, so I think that it must have killed most of them on contact.
I currently keep a bottle of dawn just in case
Even though my cats are on advantage.
I think that you could definately use dawn as a preventive measure, when first bringing a new cat into yoru home to take care of any fleas they were carrying on them at the time and then use a monthly topical.
And yes, dawn must be very safe...as I said, we rinsed each kitten 2-3, even 4 times (they were crawling with fleas!). We lathered them up good, let it set for a while, then rinsed very well and repeated... With no ill effects.