I feel your pain! I have had/still have to deal with cat/dog/kid pee. My friend FINALLY gave me the best thing to remove the smell. I had tried the vinegar thing, but that smell lingers and I hate that smell -- we tried that on our carpet and wish I would have never done that. We tried natures miracle, shampooing the carpet and nope nothing.
We bought my son a new mattress and of course before we got the new mattress pad on it (Target was sold out of them and I got a rain check but of course he had an accident)
So what I use is this:
16 oz. (2 cups) hydrogen peroxide
2 tsp. baking soda
2 small drops liquid dishwashing soap (Dawn, Palmolive, etc.)
Place all ingredients in a glass jar or bowl. Gently stir--do not beat or shake--until baking soda is dissolved.
If urine is fresh, be sure to blot up any excess urine with dry paper towels or a dry washcloth before the next step.
Pour mixture over urine spot, making sure to cover the entire spot. Allow mixture to completely soak the area being treated. Do not rub or scrub! Let sit for 24 hours without disturbing.
After 24 hours, take clean paper towels or a clean, white washcloth and blot up any remaining liquid (Again, do not rub or scrub.).
Allow area to air dry completely. If you are treating carpet, you can vacuum over the area when dry.
Makes 16 oz. (2 cups) of solution.
GENERAL TIPS
The strength of hydrogen peroxide required for the recipe is the 3% solution. This strength is what is commonly found at pharmacies, discount stores and grocery stores.
The solution is most effective within one hour of mixing, but you can keep a batch of solution in a spray bottle to have on hand for fresh accidents--it will work just fine.
Do not enclose the mixture in an airtight container (a spray bottle is fine, though), or you could have a big mess on your hands! The reason for this is because when the ingredients are combined they release oxygen. Remember making "volcanoes" out of baking soda and vinegar when you were a little kid? Similar principle here.
For really tough odors, you may have to treat the area more than once. Carpet, furniture and mattresses typically require 1-2 treatments. Concrete, wood, tile and other hard surfaces usually need 3-5 treatments (1 treatment per day).
For concrete and other hard surfaces, you want to make enough of the recipe to completely cover the stain. Pour or spray the solution on and let it soak, soak, soak. Do not mop or wipe up. Let it sit for 24 hours (depending on the humidity level, it will usually evaporate during this time). Repeat the treatment once a day for 3-5 days.
If you purchased the recipe to treat an oriental rug, please use extreme caution. Sometimes the dyes used in the rugs are not colorfast. We are not responsible for damage to rugs.
We do not recommend using the recipe on hardwood floors because we can't recommend saturating the wood. When a pet has urinated on hardwood, the urine has seeped deep into the floors. To neutralize the urine, you would need to apply the recipe so that it would seep deep into the floors as well. Due to the possibility of warping, we just can't safely recommend this.
So when this mixture hits the pee spots it will foam up so you know when you have gotten the entire spot. the recipe also states for mattress to saturate them. I did that and let it dry all day long and put a fan on it and it was good to go for bed that evening.
I hope this helps you and any other people who read this post.
Good Luck!