Hair loss on my cat's back

[akhorse7]

Hi,

A few months ago, my cat's hair began thinning in a small patch on his back, near his tail. Now, is has gotten longer: there is a strip of thinning hair that runs along his spine. It's about 1 foot long. There are a few tiny red-orange dots near the back of the thinning strip of hair; the dots look like little scabs. I thought that this may have been caused by abrasion from the extremely dirty cat door when my cat goes in and out.
What is this hair-thinning caused by and how can I stop it and help my cat grow back his hair in that strip?

Thanks!

[slvrwhispr]

Could be a lot of things. Fleas, mites, parasites, worms, an allergy, some other skin condition, stress, problems with a number of internal organs, and probably other things I'm forgetting. Bottom line, there's no way to know unless you get the cat to a vet and have them run tests. Please get kitty to the vet as soon as possible. This could be an indicator of a life-threatening illness.

[Traci]

Only a vet can tell you, with a complete exam. As Slvrwhispr duly notes, it could be a million things, your vet will probably want to do a skin scrape (painless procedure) and culture to rule out various things.

And please, INDOORS ONLY!!