mystery object

Question
I noticed what I thought to be a foreign body stuck to the rear end of my guinea pig. I had some difficulty removing it, but when I did it seemed to be some kind of bone (as if it was part of the guinea pig)and some of the guinea pigs white hair was attached to it. I'm concerned as to what this could be.
Thank you for your help.

Answer
If your guinea pig is a male it could possibly be a penis plug, these occur every once in a while, especially in males the do not breed, they can get quiet long and are usually white, they look like a calcified dead worm of some kind. Don't worry about these they are ok, but they could be a sign of getting too much minerals and calcium, if your guinea pig has a salt wheel then I would remove it, or if you are feeding Alfalfa hay then switch to timothy hay. Too many minerals will not hurt at first but they can eventually lead to problems such as kidney and bladder stones. The object could also be a piece of bedding or hay that got lodged in the bum and started to calcify from the urine of the pig. These usually are not things to worry about, just change the diet if you include any of the items above and always watch to see if anything is lodged up in that area. Let me know if you have any more questions.
Brittany