Wow, I just read this and it's so similar to the question I just posted on "Question about my geriatric cat"--
My 17 yr old cat just had blood tests - no problems with thyroid or diabetes, but he's lost weight like crazy over the winter (went from 16 lbs. to 9!) - doc says his kidneys are sluggish, so we're giving him fluids every couple days --- and he just started pulling his fur out in tufts!!! I don't have any idea why or how to stop him- sounds like maybe an old-age thing?