personally id take it depending on the area, check for your local lymes threat, as well as west nile, rocky mountain spotter fever and any other insect born isckyness...
if the area your in now has low incidents than id take the risk of not introducing a chemical...
if however your in an area of high risk, id go topical every 6 weeks (rather than once a month)
if your area is a west nile area (and you dont have cats that groom/sleep with your dog id go with k9 Advantix, (better on skeeters and repelling before bites) if youve got cats that are close to your dogs id try the frontline plus.
that being said, if you in a low risk area.
feed brewers yeast and garlic with her meals daily, the garlic is unapealing to mosquitoes, while brewers yeast helps with both skeeters and fleas. ill check into dosages on the garlic for you if youd like.
then use a herbal spray before going outside.
a good combinoation is catnip, lemongrass and lavender (all 3 are amazing bug repelants but catnip has been proven to be 3 times more effective than deet) catnip oil is expensive but you dont need to use alot, aproximatly 3-5 drops for every cup of water. ill generally then add lemongrass and lavender oils by scent, you want to be able to smell it clearly but not overpower yourself. use high quality oils and mix them with rubbing alcohol and/or water (alcohol evapourates quickly and will leave the oils in the coat while not making them look wet/greaty. mix all in a spary bottle that has a mist setting and give em a good mist before heading out into the woods ect.
i also like ot use it as an after bath spritz, just before theri dry because it smells nice
other oils that work well are peppermint, penny royal, citronella and Lemon Thyme
do flea and tick checks regularly even when using a mist (hey even when using a topical)
i do k9 advantix AND the spritz as we have realy tough bugs this part of ct, they will build up a resistance to chemicals, and ive had ticks bite through both frontline plus AND advantix. plus on the cresties theres not much in terms of oils on the skin for the topicals to sperad around in lol so the spritz is my primary on them with advantix every 8 weeks instead as "the back up" system.