This video on how to remove pet odor says to use vinegar to remove pet odor. Pet urine starts out as a slightly acidic solution but turns alkaline as it dries. Vinegar is a is an acid and a natural deodorizer. The only problem with adding vinegar to a dried pet urine stain is that it could set the stain and make it impossible to remove.
I remove pet odors from homes in Tampa FL for a living, with my experience I can tell you pet odor removal is difficult. It's biologically designed to stay where it's deposited for the purpose of marking territory. The first step in removing pet odor is to flush it out of the flooring with as much water as possible. You will have much more success in removing the pet odor if you rinse the carpet and sub floor thoroughly with room temperature water. Hot water can actually make the urine smell worse or even permanent. If you have a wet/dry vacuum to extract the rinse water from the floor. The more water used the more pet urine/odor will be removed.
With most of the urine removed with a thorough washing you can move to the next step of sanitizing and deodorizing the floor. Mix one gallon of water with one gallon of distilled white vinegar in a lawn sprayer like what you see in the video. Spray all the hard and soft surfaces in the home and let it dry out. I recommend spraying the entire two or three times, letting it dry between applications. If the pet odor remains it's time to call a professional carpet cleaner.