I'm glad that blocking the place off seems to work. That indicates that the odor is drawing the dog back. I know that you are cleaning the area up but if not done correctly, the odor remains and will actually encourage a dog to return to the spot to strengthen that dog's particular scent. Dogs mark to urinate and also mark their territory. When the scent starts to fade, they feel a strong need to urinate in the area again. In addition, a dog's nose is much more sensitive than ours. Most cleaners work to mask the odor from human noses and not a dog.
A good enzymatic pet odor remover is needed to remove the odor. You also need to ensure that the cleanser reaches all the urine in the carpet. Usine soaks down into the carpet and spreads out once it reaches the sub flooring it spreads out. Any cleaning product needs to be kept on the area to allow it to also reach down into the fibers and the subflooring. Also male dogs tend to urinate upwards and let the urine fall or run down an object so it is also important to clean any object nearby.
Nature's miracle is a good cleaner but I've found a lot of enzymatic cleaners work well but often take a second or third pass of cleaning to be effective. You should also be sure he has a clear signal he can use to let you know he needs to eliminate as well. Put a bell or other noise maker on the door low enough for the dog to reach. Each time you take the dog out, ring the bell. The dog will associate ringing the bell with going out and one day ring the bell to signal to you that he needs to go out.
If he is urinating often or more than normal you might want to have him checked for a urinary tract infection. Common symptoms of a urinary tract infection are frequent urination, dribbling urine, blood in the urine, squatting frequently to urinate, strong odor to the urine, inappropriate urination and straining to urinate as well as an increase in fluid intake. He has inappropriate urination so check for other symptoms.
A dog with a UTI does not always show all the symptoms and typically displays 2 or 3. I believe you need to have your Vet check your dog out so it can get medication for the problem if your dog is displaying 2 or more of the above symptoms..
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