I have an indoor cat here at the office, he's just over 8 years old.
I've had him since he was 2 weeks old. He's a big, long hair, never
had health issues other than weight. We had to move him out of the
house when he bit my 1 year old. His diet has been purely Innova
reduced fat adult cat food for the past 18 months. It has not helped
his weight, and I measure his food out and provide it over two
servings using the recommended amount on the bag for inactive cats
(0.64 cups/day for 14 lb cat that needs weight loss, this guy is
around 18-19 lbs).

Anyway, he's always had this giant fluffy tail. He did on Friday. I
came into work today and one of my employees asked what was wrong with
his tail. It now looks like it belongs on a short hair cat. It's
thin. There's no fluffy hair. I don't see any hair around the office
that looks like it may have been shed en-masse. It's never done
anything like this before. My first though was nutrition as I realize
it would be better for him to give him a mix of wet/dry. Still, in 3
days that's just strange... and where did the hair go? I'll make a
vet appointment, but figured I'd ask here as well.