I've used cedar oil by cearcide for years. It's safe around dogs, it can even be lightly sprayed on them to kill or deter fleas. It does have to be resprayed every so often since it is an oil. I keep a quart around at all times and I have a couple of little spritzer cans too. This is what I use...
Best Yet - Organic Pest Control Insecticide by Cedarcide : CedarCide