rex rats loose hair?

okay, so i know we've talked about double rex babies loosing their hair is normal... but i'm noticing that some of my rex adults are loosing hair as well. i took a good look at them and don't see any mites etc on them... so i'm wondering... is this normal?

they are on aspen bedding.
sleep in polar fleece hammocks.
becky's rattie food mixture (which changes everytime i got to the store for variety).
senior dog food - nutro.
cage cleaned once a week or 10 days... depending on how dirty it gets - in proportion to amount of ratties in cage. (wire cages)

treats: bones, left overs from dinner if appropriate, dog biscuits, chicken jerky from the feed store (they love this stuff - just got some today for the first time so it wouldn't have anything to do with their hair loss), rice, chocolate once in a blue moon, thinking of offering them a bit of timothy hay and other grasses which we get for our bunny.

so... any ideas?

Sounds normal. I know I had a rex rat a few years ago and he was great for loosing and regrowing hair.

A couple of my future breeders which are rex have small areas where they are missing hair on their face or top of their heads. I'll try and get some pics to see if its the same thing you are having

Normal.. they just have thin hair, and it does get patchy sometimes.

whew... okay good to hear. I'll relax then.

I figured it couldn't be mites (that I was somewho missing seeing) since none of the silk furred mice have a single balding area LOL