Dog urine can be removed from a carpet or furniture with a hydrogen peroxide mixture. Hydrogen peroxide is an oxidizer, which kills bacteria and neutralizes the salts in the urine, allowing the furniture or carpet fibers to dry out.
Urine contains salts, which keep the carpet or upholstery fibers moist for months. When the fibers stay moist, bacteria will grow and emit a smell. Growing bacteria, especially in dog urine, will have a strong odor.
To get rid of dog urine odor, dry up the area where the dog urinated as much as you can with a dry towel. Mix up two cups of hydrogen peroxide, several small drops of dishwashing soap and two teaspoons of baking soda. Stir slowly, so it will not bubble up. Pour the mixture liberally over the odorous area and let soak for 24 hours. Blot up the area with a dry towel. Let it dry. Vacuum thoroughly.
Test a small inconspicuous area of the carpet or upholstery first, to make sure the hydrogen peroxide mixture does not bleach out and ruin it. Use the peroxide mixture within an hour or it loses its potency. Do not store it in a closed container, or the lid may pop off because hydrogen peroxide mixed with baking soda creates oxygen.
You can mix hydrogen peroxide with vinegar, bleach or mouthwash and it may be just as effective as baking soda on dog urine.
Dog urine that has set for a long time may need two or three applications of hydrogen peroxide to neutralize it. It is best to use the hydrogen peroxide mixture as soon as possible on dog urine.