pet rats tail

Question
hi, i've got two healthy males. but one of them i've noticed a hard little clearish-whitish tip about a sixth of an inch on the end of his tail. there's never been any blood, no pain (i pinched the hard tip to check) i don't know if it's bone or dead tail skin or what. it doesn't seem to cause discomfort to him, but it worries me. they don't fight, he doesn't bite at it. it looks like it could be the very tip of bone in the tail minus the skin, but it looks the skin just shrunk around it. how would this have happened and what can i do? thanks.

Answer
Do they have any hammocks or anything with strings? He may have gotten a thread (or even human hair) wrapped around the tip of it, killing off the end of flesh there. Over time, that tip will fall off and the tail will heal - stumpy, but fine. Unless the hair is still wrapped around there. Check his tail carefully for any ligature marks at all, and if in doubt, take a soft bristled toothbrush and gently scrub his tail to remove anything invisible. He may also just have gotten it slammed in a cage door without anyone (even him) realizing it - the possibilities are endless.

Unless it continues to die off, I wouldn't worry about it though.