How can I get old pet stains out of my carpet?

https://spotremoval.coit.com/how-to-remove-urine-from-carpet

I have 2 dogs and 3 cats so I am very familiar with this problem! I use a steam cleaner but don't use carpet shampoo---- I use an oxygenated cleaner like OxyClean or Awesome Orange (my favorite) mixed with water in the canister - works great!!! For small spots I swear by Spot Shot in the aerosol can.

I like a Woolite spray on pet cleaner

Folex Carpet Stain remover, spray on the stain and gently rub the stain out if too many stains Folex the stains and have a carpet cleaner clean it. Years ago I got tired of pet and kid stains on our carpets, had them all removed and slate installed however I would still remove the carpet if I could not afford to replace with a flooring other than carpet, I would live with the cement or wood floor and paint or use the paper bag flooring magic fix, much better than living with the stains and odor. I even had our oriental rugs cleaned and stored due to the additional and endless work carpets take. Good luck!

Use nature’s miracle and rub inly the stain.

Personally I swear by Nature's Miracle, but if you want to use household stuff, this is what I found at One Good Thing:

My best tip is for pet potty spots on the carpet. I use good old vinegar and baking soda. The steps are the important part. Pour enough vinegar to soak the stain and THEN add a small amount of baking soda. If you do the reverse, you will have a noisy, bubbly mess. Do it the right way, and you can hear the recipe cackling away, telling you how it is cleaning and deodorizing without leaving any residue. You need to let the spot dry for a day or two before sweeping up and then vacuuming. We cover the spot with a bowl or plate so that we don’t have baking soda kicked from heck to breakfast. You can actually see the yellow color being absorbed up into your little mountain of baking soda. Works on old stains too!

I use Nature's Miracle. It's an enzyme cleaner and works wonders on pet stains.