Vinegar. Try this!
Dog urine smell can be removed with a solution of water and vinegar. Blot the area with a rag and then blot dry to remove any residue of water. Professional shampoos are made and used so that not a lot of residue soap remains in the carpet after cleaning and are usually compatible with the rug fibers so that you do not get any damage.. If excess water or soap is left in the carpet it will only get dirty much faster as the fibers become sticky and attract all dirt. I use Bissell rug cleaner.
For horrendous situations like this only use Cleaning vinegar with at least 6% acidity. Walmart has ‘cleaning vinegar’ that’s weaker than 6%; don’t buy that. Heinz cleaning vinegar is what you want. Go 1 cup cleaning vinegar to 1 cup water, and use more vinegar if needed.
Would a shampoo cleaner work as well