I buy "First" magazines at the grocery store because of there great tips on household items that can fix about anything. Here is what it had in it last month....
Remove pet pee from the carpet. In a mixing bowl, combine one 16 oz bottle of hydrogen peroxide, 2 tbs. of baking soda and 1 tsp of liquid dish soap. Saturate the spot with the solution and rub with sponge. The oxidizing mixture breaks up uric acid crystals and neutralizes the smell