One of my young rats has a small lump on the right side of her body. She HAS been spayed. My Question is, are lumps ALWAYS tumors or could it be something else? We adopted her from a rescue in October and she had recently been spayed before we got her. Her hair was still growing back at that time. This small lump is sort of near where her hair was re-growing. Should I just keep an eye on it to make sure it doesn't get bigger? Any ideas as to what it could be? I just noticed it last week. I would say it is a little bigger than a pea.