To be honest, shaving is the best. Here's why: Even though some knots have the ability of being combed out, it does pull and an older cat's skin will probably be more sensitive to this (as shown by her attacking) Shaving does not hurt the cat, but they may need to be placed in a semi-uncomfortably position for a few minutes (Most cats don't like to be laid on their back). Now, if you just ignore the knots, they will not get better. They will only get worse. The tighter the knots, the more pain to the skin. Air cannont reach the skin either. I have seen such bad matting (I am a groomer) that the fur literally peals away from the skin. I would find a vet or preferably a groomer who will do only the bare minimum needed to make her comfortable (vs. the whole bath/brush routine) have the knots shaved away and sent home. This is more humane than allowing the mats just grow until she passes away.