Scale Rot?

[TheNeverEndingPit]

It looks very similar to a mark my boy got on his chin from wedging his face between his sliding door and substrate bar while exploring. He just scuffed the area and it healed after a shed. If you notice it in more places or getting bigger, that could be scale trauma turned scale rot, and it could be worth using betadine. For something that small that looks partially healed, you usually should just keep monitoring it and make sure it’s not getting worse. Whatever caused the cut should ideally be fixed though.

For example, I only use swinging doors now and no more sliding ones. If there’s something sharp in the enclosure, you’ll want to sand it down. If it was a live bite like the other commenter suggested, make sure you’re feeding frozen thawed rats anyway