I'm sitting here brushing my cat Loki, male, 3 1/2 yr old brown tabby, and I
notice on the brush not only is there dandruff, but also little
browish/black specs, almost like flea dirt.  I checked him thoroughly for
fleas, and also brushed the other cats (with a different brush) to see if
they had the same thing, and they are all fine.  Loki's coat also feels
kinda dirty, mostly on his back.  Like he hasn't been cleaning himself or
something.  He feels OK on his chest, face, and neck.
Should I give him a bath?  Could it just be from the dryness of the house?
It's been really cold here and the heat's been cranked up.  He's due for his
vaccines anyway, so I'll be taking him to the vet soon.  Does this sound
like a cause for concern?

Thanks,
Kelly