2 cats licking their hair off....?

Two of my cats are roughly 3 yr old fixed females. They both came to us as stray cats, and are not very social. They hide in the bedroom the majority of the time, coming into the common areas of the house on weekends and at "treat" times twice a day. They like getting love from us around bedtime and sleep at our feet but are mostly independent kitties.

In the past two weeks I have noticed them both spending a lot of time licking their back ends....at the very back of their backs, where their tails connect to their bodies. One kitty is black, the other dark grey so I hadnt noticed until I was petting them in the past couple days just how bad it has gotten....they both "bald" spots on their backs right where their tail connects, and the grey kitty is missing about 1/2 inch of fur at the base of her tail.

The spots aren't really bald, because there is hair....I would say it really feels like those spots have been shaved to about 1/8th of an inch or so. There is never an actual bald spot, just very short spots. These are indoor only cats and the hair loss is on the spots that they are licking the most.

We have had no crazy changes in the past two weeks, or so. We moved to this house back in May, and the cats adjusted well. We added a kitten in June but he doesn't really interact with these two. It is just about time to deworm them again, could that cause it....if they did get worms (we had baby kittens for a little while that had their own litterbox but I can't be sure other cats did not use it....all the other cats have since been dewormed except these two because it wasn't time for them yet and we didn't see any signs that they needed it....) would having worms cause them to obsessively groom their backsides to the point of losing this hair?

I am planning on calling the vet about this as well, just thought I would see if anyone had any advice/suggestions for me! Thanks!

Have you checked them for fleas? I know some animals have more reaction to fleas than others and will lick their bottoms. Sometimes you can find a food amount of flea debris and/or flea feces there.

I would definitely say to letthe vet give them a good lookover though.

This is more than likely a stress reaction if fleas/parasites are ruled out. I have heard of many instances where cats over groom due to stress to the point they are bald. Many people have had great success with anti anxiety meds, so that may be an option once you speak with your vet. Good luck hun!

The licking at the base of the tail is more often a flea allergy. It could just be flea dirt that is residue in the bedding or actual fleas. I would see if they have been treated for fleas. 

The way you describe the cats' behavior would indicate stress, but the location of their licking is what indicates fleas and/or flea allergies. 

Here is a useful link that talks about skin disorders and excessive licking in cats http://manhattancats.com/Articles/Skin_Disorders_in_Cats.html

I have a cat with food allergies, so I did a lot of research about licking, scratching, etc. Just about every site I found said that if it is at the base of the tail it is more likely flea-related. I would start there, if I were you and check for other things if it is not fleas or flea allergies.