Blot up as much urine as possible with clean paper towels or a dry cloth
Remove bedding and wash it separately
Mix equal parts white vinegar and water in a spray bottle
Lightly spray the stained area
Blot again with clean towels
Sprinkle baking soda over the damp area
Let it sit for several hours or overnight
Vacuum up the baking soda
If odor remains, repeat the vinegar and baking soda process
For stubborn stains, use an enzyme cleaner made for urine
Allow the mattress to air dry completely
Place the mattress in sunlight if possible
Use a mattress protector to prevent future stains