Write the next sentence in the following story.

How to get rid of fleas on rats
Observe if your rat is scratching more than normal.
Often a rat will scratch a flea infested part of its body more frequently and often quite vigorously. This area can become irritated, red, or inflamed from scratching and from fleas feeding on your rat's skin.
Missing patches of fur or red scabs is a good indication that something is irritating your rat's skin even if you don't see them scratching. Fleas like to hide in densely covered areas of animals.