What is a normal amount of scratching for Guinea Pigs? Before we got a friend (Ruby) for Marshmallow, I noticed that Marshmallow seemed to be scratching herself quite a bit. Sometimes even kind of biting herself. Since we got Ruby, there is not as much scratching/biting. But they both will occasionally scratch at themselves and seem to be a bit itchy. Otherwise, they seem fine. There aren't any patches where fur has fallen off or anything. Sometimes it seems like Marshmallow gets itchy after someone pets her. Not sure about Ruby since she still doesn't let us pet her much.