I honestly feel that frontline is very strong for small breeds it contains very harsh ingredients that will burn a small breeds skin. What I've used with my dogs is this great product called NEEM it is made in Switzerland safe for people and animals to use it is made of natural plants. This product has worked miracles. They have the set where you buy the shampoo and the spray. I tell the groomer to apply it with my dogs regular shampoo and when they are all dried up give them a quick spray that prevents from fleas and ticks from crawling up again. My dogs use it when they go to daycare and it is great although I only used it twice because since then they've. Never had fleas jumping on them no more.
Here is the web page go to the shop now tab and look for the new products and you will see the NEEM SHAMPOO AND SPRAY I saw my groomer in Beverly Hills buy one and charge double for a bath with the NEEM product.
http://analilia.swissjust-usa.com/Pages/Homepage.aspx