I'm just re-reading this thread from 2010 on mats. Cassie has started to get clumps of fur at the base of her tail. I just combed out another one this morning. She's been surprisingly good about letting me comb her enough to wiggle them loose. I found two great ideas in this thread: 1) try a human comb; and 2) get an undercoat comb. I have a comb with wide and narrow-spaced teeth and she has never minded being combed. I thought I read a tip somewhere on PT about trying a bit of Vaseline to help loosen up a very tight mat, but I could very well be wrong.

Edited to add: Columbine-- Cassie would give "cheek bumpies" to your slicker brush all day long if you'd like to hold it for her !