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 until completely dry
Vacuum up the baking soda
If needed, apply an enzyme cleaner made for urine
Let the mattress air dry fully
Use a fan or open windows to speed drying
Repeat if any odor or stain remains