WD-40.....it works. Spray your dogs down with it and then just rub it into their coats. Within 30 seconds you'll see fleas come to the surface of their coat and then presto, they fall over dead. Also makes their coat nice and shiny. Another advantage of it is the residue stays on the coat for a couple of weeks. Try it - your dogs will appreciate it. Probably not the best thing if you have inside dogs that like to sleep on the couch instead of their bed. Been using it for 30 years.