You can rent rug doctor steam cleaners, it wasn’t expensive. They have locations listed on their website. www.rugdoctor.com/rent/ We did every rug in our house before we moved in. It was amazing the amount of dirt that came out of clean looking rugs.
I may do this. We were also thinking of getting a professional in to do it for the first time since we don’t want our dog to think peeing inside is okay though she is house trained. But a rug doctor sounds far more affordable.
You honestly might want to replace the carpet. The carpet and pad and possibly the subfloor may be urine soaked. You can paint the subfloor with a smell blocker and then put in new pad and carpet. It’s a lot more expensive but then you know what you are getting. Also carpet doesn’t have a huge lifetime (depending on the material and quality) so if it’s 10+ years it might be at its age limit.