Liquid Only Dilutes and Spreads the Dog Urine!
Any liquid based cleaning solution (including steam cleaning) doesn't work because you will never be able to "blot" or wash all of that wet liquid mess out of your carpet.
You still have dog urine stains and smell because they are deep down in the fibers, pores of the surfaces! Liquid products cannot absorb and extract the dog urine stains and smell and only mask the smell for a short time. Eventually the dog urine stains and smell returns!