Cleaning leather is never easy. And cat urine has its own special place on the world's list of "Odors That Won't Go Away." Combine these two and you have got a mess. The options aren't pretty. You try to remove the smell, making the stain worse, or you focus on the stain and smell like a cat box. The only real option seems to be throwing the entire thing out and replacing it--the leather that is, not the cat. The following guidelines focus primarily on the removal of the urine aroma, with stain removal being secondary. It has been effectively used on both leather shoes and bags to remove both stains and odor.
Sprinkle Nature's Miracle into a piece of old cloth. From the side of the leather that doesn't show, press the damp cloth against the soiled area. This will destroy the bacteria causing the unpleasant aroma.
Leave the cloth against the soiled area for approximately one hour, sprinkling with more solution if the cloth begins to dry out. Be warned, making the urine wet generally causes an increase in odor. This does not mean the product isn't working.
Select a box that is large enough to hold the damaged item. Fill the bottom of the box with Borax to 1 inch deep. Add the damaged item and sprinkle additional Borax over it.
Place 1 cup of activated charcoal pieces in a plastic storage bag. Leave the top of the bag open and place the charcoal in the box with the soiled leather.
Close the box and put it in an out of the way location. After five days, open the box and remove your item.
Clean the leather with saddle soap, focusing on the stained area. Pat dry and treat with leather conditioner. If the stain remains, treat with stain remover formulated specifically for leather.
If at any point the cat aroma seems to return, repeat Steps 1 through 5. Between the enzymes in the Nature's Miracle and the combined natural odor removal power of the Borax and the activated charcoal, the urine smell should vanish completely.