Tearing out fur

Question
My cat, Kato, is 10 years old.  He has been tearing out his fur (yet still having regrowth) on his upper back near spine in a straight line as far as his head can turn to do this and it is on both sides.  Now lately, he's pulling fur near base of tail on right side and along side the rear legs and alongside the back legs.  There is another patch he's been pulling out at bottom of his tummy left side.  Also, noticed that he's having dandruff or flakiness. I've checked for fleas but do not find it anywhere.  He's housebound.

I'm concerned whether this is a skin problem or a behavior problem.  He still has fur, but it is getting thin, with no "noticable" bald patches. On close inspection, fur is rough and skin dry and dandruffy.

When he does this tearing out of fur, as though he's itchy and trying to pull whatever it is out and obviously at difficult spots for him to scratch.

His litter is Swheat Scoop and wonder if it's an allergy?  He's had this kind of litter for over almost 8 years.  But this tearing out of fur problem has started within past 6 to 8 months.

Is there an answer to this?  

Answer
why dont you take him to the vet for an exam and bloodwork.  

MANY cats can be hyperthyroid and have skin problems with the disease (which is treatable!)

go ahead and make a call today and have him checked out so that you can make him more comfortable.