lakota: You can use a number of products as mosquito repellant for dogs. There is the Brewers yeast and Garlic Tablets - I use them and they seem to help with the mosquito but not the biting flies like Mayflies or ticks - my guys love them and I give them as a treat on a daily basis - it may be overkill but upstate NY during hte summer is loaded with every sort of flying flesh eatin' critter you can think of. You would want to get them from a pet supply company for the best bargain.
I will also use a bug spray, like Cutters or Deep Woods Off - they seem to work pretty well. A trick for applying any spray however is to cover your dog's eyes and snout when spraying it on, and put some in your hands to wipe their snout and ears with. Or, just spray some into your hand and wipe the dog with it.
There is also a veterinary product called Advantix, which I have used this summer, that appears to be pretty good. It is supposed to work for fleas, ticks and mosquitos, and this summer I have not had to pull one tick of either of my 3 Standard Poodles (all of whom run through the woods and deep brush). Hope this helps. Mikey.