salt wheel

Question
How can I tell that my guinea pig(s) are eating/licking their salt wheel?

Answer
Guinea pigs don't need a salt wheel. They get the salt they need from their pellets. Just make sure you are feeding a good quality pellet made for guinea pigs. Don't use the kind with the seeds and colored fruit loops in them. Those are just eye candy for the owner.

But to answer the question, you should see marks in the salt wheel where they have either chewed or licked. But again, that's not really necessary for the guinea pig's well being.