A pet mouse engages in fastidious cleaning of himself, much like a cat, and rarely needs a bath. However, when a mouse is active during the day, he may get curious and into a sticky mess. In this case, you need to clean him properly without immersing him in water and scaring him.
Run the water in a kitchen or bathroom sink until it becomes lukewarm. Don't plug the sink or immerse your mouse in the water.
A Mouse Pad
Place your mouse on a towel on the countertop. The towel gives him traction and calms him. You may need to offer some mouse treats to get him to stand or sit quietly on the towel if he hasn't had a bath before, or is fairly new to your household. Keep on hand on your mouse's tummy or back at all times to prevent him from moving from the towel and falling into the sink or the ground.
The best shampoo for a pet mouse is a gentle cat shampoo. Wet a washcloth and rub in on your mouse from behind the ears to his tail to make his fur damp. Apply a drop of two of shampoo to the mouse's fur and lather him.
Use a Toothbrush
Gently brush your wet and lathered mouse with a soft toothbrush from behind the ears to his tail. If you are removing a mess in his fur, rotate the toothbrush in circles over the area you are cleaning. A toothbrush separates his fur and gets messes that may have penetrated to his skin.
Soak a washcloth in the stream of warm water, wring it out so it is slightly wet, and wipe your mouse to remove the shampoo. Repeat this process until you remove all shampoo from his fur and skin.
Dry your pet mouse with a towel until he is almost dry. If the weather is cool, turn a blow dryer on the cool setting and the lowest speed and dry him thoroughly. Hold the nozzle at least 12 inches from your rat's body while holding him in your other hand and ruffle his fur to get him dry.