Red patches on rats tail

[Lielleore]

Does anyone know why my rat might have these red patches on his tail? He doesn’t seem to have any symptoms otherwise. He’s eating and drinking as normal and has normal energy levels. It doesn’t seem to be itchy for him as I don’t see him over grooming the area when he’s out and about. We have a bio active cage for him and I’m just worried that the cage could have somehow cause it? Any ideas as to what it might be? Also I’m not sure how to post pictures on here so if someone can let me know how then I can post some pics of what his tail looks like!

 

[phycomantis09]

Here is how to post photos. If you post a picture I might have a better image on my mind.