My rats have a black splodge on their backs- what the?

Question

my two female rats have a black splodge on both of their backs- is their colors changing? it looks more like a bruise on their fur. its kind of light black and I'm wondering what it is so...

what is it??

Answer 1

How old are your rats? I've seen some younger rats grow new colored fur before, but its a gradual change and doesn't appear suddenly.

Is it possible to get photos? I've been pretty lucky with the health of my Rats so far..

EDIT: Also, have their eating or behavior habits changed at all? Mite spray might be a good precaution if you haven't used it already.