Back in the mid-80's when we had Labs we never ever had a problem with fleas. Our Labs had beds filled with mostly cedar, not the poly fill stuff they put in them these days. The dogs always smelled like cedar and we never ever had to use flea medicines or sprays or powder or anything.

I sometimes wonder if all of the flea medications the vets give out are not making the fleas immune and actually making the flea population worse.

I have never heard that cedar was harmful to pets.