Anesthesia and a hundred bucks to shave a cat's hindquarters???? Good grief!!! My Specs has that problem and he, too, likes to be brushed. So you can probably get at that part after you've brushed him elsewhere for a few minutes. When he's calm, he may even let you cut them out. Specs does. Not very helpful, am I? But that's what works for me.

Blessings,
Mary