To get a dog urine smell out of your carpet mix one part vinegar and water together and spray it on the spot where the dog has urinated.
Then sprinkle some baking soda on top of the vinegar and water and let it sit for 15 to 30 minutes then use a carpet cleaner to go over the carpet to remove both the urine and baking soda and vinegar from the carpet.
You can also buy some pet urine odor neutralizer which will neutralize the pet urine odor in the carpet and then just go over the carpet with a carpet cleaner.
You can also remove dog urine or other pet urine from carpets by mixing hydrogen peroxide with some dish soap and then scrub the area where the dog urine is and then if possible use a carpet cleaner on the carpet as well for best results.