I dropped by my vets office today to pick my flea and heart worm preventative and my vet reminded me to wait 48hrs before or after bathing to apply the flea treatment. I had never heard that before and actually always applied it just after they were bathed and dried. She explained the treatment is absorbed through the oil glands in the dogs skin and it is not as affective if applied on freshly washed skin or if the skin is washed 48 hrs after applied. Huh...I've been doing it the wrong way for YEARS!