Im not sure what its from, but my best guess is that its from Ruby sliding on the carpet. When she plays or chews on her toys she slides on the carpet every now and then to reposition herself, or if she toy rolls away she will slide after it. But now, there is a hairless patch on her chest between her ribcage. And its gotten slightly larger than it used to be. Is it from carpet sliding or something else? Could it be as simple as friction from the carpet or something more serious? Here are two pics, and the bald area is circled (taken today) :
the area looks completely normal except that the hair is worn away. Its been like this for atleast a year.
In the picture, it looks like that area has dry, scaly skin, but its not. Its like peachfuzz hair, really soft.
Hmmm... It does not look irritated at all like a hot spot or something she has been licking or chewing on to create the bald spot. Someone will chime in with some good advice soon I'm sure, but I would not be worried as it just looks like a natural marking like the one below your circle.
Is the peach fuzz always there or does it grow, drop and grow again?
Yes, she does wear a harness. Im not sure if it touches that area of her chest, but Ill check next time I put it on her! Because, now that you mention it, the area does seem more "noticable" since I started using a harness a couple months ago.