To be honest, my dogs don't wear boots all that often. There have been a couple of occasions where temps have dipped below zero and there was a lot of snow and ice on the ground and boots became necessary. I knew it was time to bring them out when they couldn't go more than a few steps before their little paws would freeze up and they'd start limping a bit.
If you are worried about the pads of her paws, you can try using a balm to help keep them moisturized and protected from salt. I use good old fashioned Bag Balm (http://www.amazon.com/Bag-Balm-80z-8-ounce/dp/B00FNKXZLI/ref=sr_1_1?ie=UTF8&qid=1448301541&sr=8-1&keywords=bag+balm+8oz). Musher's Secret is another good product (http://www.amazon.com/Mushers-Secret-Pet-Paw-Protection/dp/B0002XIZXY/ref=sr_1_1?ie=UTF8&qid=1448301569&sr=8-1&keywords=musher%27s+secret).
Good luck!