Most rats do not need to be bathed. I've been asked this question several times and I give the same answer every time. If they smell bad it's probably time to clean the cage instead of giving them a bath, a dirty cage will make them stinky. But sometimes a rat may need to be cleaned and some rats like water and some do not. It's not a good idea to force your rat into water if it's scaring them. But sometimes it is necessary to clean them and I'll give you tips on how to do this while not stressing your rat out.
Rats only need to be cleaned or bathed if they get into something sticky, smelly or they are getting so old they stop cleaning themselves, which does happen to older rats. In which case you will need to help clean your rat.
You will need:
A small bowl with warm water
2 medium size towel
A wash cloth
Unscented Baby wipes
Small Animal Shampoo
The small animal shampoo I've used is called Squeaky Clean and you can find it at most pet stores but you can also use Baby Shampoo or Dawn Dish soap.
To begin you should give your rat a treat like a yogi drop and sit somewhere they are comfortable. I do this on the couch because they are very comfortable there.
Put one of the towels on the couch next to you and put your rat on it. This is so your couch doesn't get wet.
For small areas to clean like a spot in the fur, a dirty tail or just cleaning the genital area for older rats. You can use just the baby wipes and wipe your rat down and clean them off.
For tougher more serious smells, a really dirty rat, just dip the wash cloth in the bowl of water, wring it out and wipe your rat with a wet wash cloth. use a tiny bit of soap and keep dipping the wet wash cloth into the water until your rat is clean. Giving them a treat while you do this will keep them distracted long enough for you to finish.
If your rat has hind leg degeneration, you may also have to clean their ears out for them. To do this just hold your rats head under his jaw in one hand and pet him, once he is relaxed gently pull the ear slightly back and gently wipe the inside of the ear canal with the Q tip. Do not insert the Q tip into the ear canal without a veterinarian's assistance as you can hurt your rat if you go to far.
After you're done, wrap your rat in the other towel and pat them dry as much as possible. Some rats will curl up in the towel and let you hold them until they dry. But most will start cleaning themselves right away and will keep cleaning until they are dry.