Slicker brushes aren't intended for single coat breeds. You should be brushing her frequently which helps distribute her natural oils and obviously keeps mats at bay. You can buy a dematting comb to work through mats or I use a chris christenson wooden pin brush. It is the best money I have ever spent and glides through mats. Use the wooden pin brush, then a regular pin brush and finish with a greyhound comb. A terrific conditioner is made by summerwinds...
here's links to the products.
Pin Brushes Summerwinds - Coat Care Products