It seems almost impossible to eliminate the urine odour from a carpet or hardwood floor after a dog has had an "accident" in the house. Dogs will often return to urinate in the same spot after they have marked it once. You will need to be proactive and discourage the dog from urinating in that spot again. You will also need to thoroughly remove the odour from the soiled area to discourage the dog from urinating again in that spot. Covering up the smell of dog urine is difficult. In most instances, you can eliminate the odour only through thorough cleaning.
Look for any soiled areas and also use your nose to determine the precise location of the soiling. Urine smells linger long after you have cleaned up the spot. Consider buying a handheld black light urine detector from a from a home supply store to help you find the soiled areas. After turning out the lights and identifying the soiled areas with the black light, mark the soiled areas with chalk.
Clean the soiled area with cool water and soak up as much of the urine as you can with a combination of newspaper and paper towels. Place a thick layer of paper towels on the spot and then cover with a layer of newspaper. Step on the padding for one to two minutes and repeat this process until the area is barely damp.
Rinse the spot with cool water and blot with paper towels. For spots that are already set, rent an extractor or wet vacuum and use only clean water and no chemicals.
Apply a pet odour neutraliser or carpet stain remover once the area is completely dry. If you still notice an odour, pull up the carpet to determine if any moisture has soaked down into the padding beneath the carpet. You may need to replace that portion of the carpet and padding.
Remove and replace any soiled varnish or paint, making sure that the product is labelled as safe for pets.
Do not use steam cleaners to remove urine stains from carpets; the heat will permanently set the stain and odour into the carpet fibres. Avoid using chemical cleaners with strong odours such as vinegar or ammonia because the pet will still be able to smell the urine scent and will continue urinating in that spot. Retrain your pet from using the soiled areas as an elimination area and use positive reinforcement to direct your pet toward the appropriate elimination area. Move the soiled paper towels and newspapers outside to the area that you want the dog to use as his elimination area. If the dog has urinated on any bedding, first wash the bedding and then cover the bed with a vinyl, flannel-backed tablecloth that is easily washable and unattractive to the dog.