We all love our pets. They're family. They are just like kids in our house. My wife calls them the fur babies. As much as we love our pets they have accidents, especially when they are new to the home. We've had 4 different dogs and 1 cat since we've lived in Tampa FL and it used to be difficult to find a good solution for pet accidents in the carpet. Now my wife owns a Chem-Dry franchise, Chem-Dry of Tampa FL, and we clean carpet and upholstery for a living. I can tell you without at doubt, not all pet urine cleaners work the same.
It most case if you can get to a urine spot in the carpet right away you've got a good chance of getting it out without any issues. Once it's dried its a completely different story. Urine crystalizes and becomes very difficult to remove. If it has penetrated the carpet and found it's way to the carpet pad underneath it is extremely difficult to remove. Specialized equipment may be required to remove the urine from the carpet pad while the carpet is still in place. Most pet urine cleaners are not designed to neutralize urine crystals, making them completely ineffective at cleaning urine.
If you are having trouble with dried urine spots in your carpet your best option is to hire a professional carpet cleaner, specializing in urine removal, to get the urine out of the carpet and the pad underneath. Not all carpet cleaners have experience with urine removal so make sure to ask before hiring.