Wood flooring or furniture and a puppy or an elderly dog is not always a match made in heaven. Although any odor will disappear in time, and dog urine has nowhere near the pungency of cat urine, wood, being highly absorbent and reactive, is likely to stain. You might not get an obvious yellow stain -- wood urine stains often become very dark -- but it still spoils the look. Before resigning yourself to covering the stain with a throw or rug, try removing the urine. The faster you do this after your dog had his little accident, the better. Old stains, however, are still treatable.
Mop up any liquid that hasn’t sunk into the wood with paper towels or a cloth.
Alternate sponging the site with a wet cloth or sponge and blotting with a dry cloth. Repeat several times. Avoid using harsh cleaning products, which can also stain wood. Use a squirt of dishwashing liquid or a cup of white vinegar in a bowl of water. You can also sponge tomato juice over the site to help remove the odor; there are plenty of commercial products that do the same job -- select one suitable for wood. Sponge finally with plain water and blot several times.
Place a dry cloth over the site. Weigh the cloth down with a couple of heavy books or similar flat items and leave for a few hours. The cloth draws up the last traces of water and urine. Replace with a fresh cloth a couple of times.
Remove the last cloth and wait at least a day, preferably longer, until the site is completely dry. Examine it carefully. If the wood has become paler or darker, or has a yellow tone, decide whether it is noticeable enough to be irritating.
Sand the top layer of the site. At this point, you’ll be able to see how deeply the urine has penetrated. Heavy sanding may be enough to remove any staining if the urine did not penetrate deeply.
Create a weak solution of household bleach in water -- about one part bleach to 10 parts water. Alternatively, use a proprietary bleach for wood. Wet a paintbrush with the solution and brush a small area of the stain. Leave for an hour and then wipe clean with plain water. Compare the bleached area to the surrounding wood and the stain. If it is noticeably paler than the rest of the stain, proceed cautiously. Paint on the solution and sponge off after a short period. Repeat until the stain is almost as pale as the surrounding wood. If no effect is obvious initially, use a stronger bleach solution or leave it on for longer.