Green on the tail

Question
QUESTION: Hi,

My pet rat Charlie has developed some green spots on her tail. She doesn't appear to be irritated by them.  Do you think that it might be some form of fungal growth, a reaction to some of her food (usually dog food or healthy table food), or maybe some of her new bedding (paper-based) has rubbed off onto her tail???

Any advice that you could give would be greatly appreciated!

Thanks!
LB

ANSWER: Without seeing it, I can't really give you a solid answer. Try washing her tail with a soft toothbrush and some light soap and see if it appears to be just pigment or actually spots of gross flesh. Is there any smell at all to her tail? Has it seemed to get any worse?

---------- FOLLOW-UP ----------

QUESTION: It doesn't have any sort of odor, but I am not sure how long it has been there.  I am concerned about getting nipped if I scrub her tail.  Do you have any advice on how not to get bitten when I am 'brushing' her tail?

Answer
Just police her reaction. If she's way aggitated by it, don't worry about it and just keep an eye on her to see if it grows or gets worse. I've never heard of a green fungal infection that is not obviously an infection -- normally they're disgusting gangrene-like flesh that smells to high heaven.