My husband and I rented a rug cleaning machine from a hardware store. I put just a tiny bit of Oxi Clean in the water and our rugs came out really nice.
Without going crazy doing the entire carpet first off rent or borrow from someone a black light Yea the one that makes all those 70 posters glow. Then at night when it is dark in the room turn on the light. This light will make all sorts of animal stains and oops glow green.
Now you know the real important areas to address. Purchase Natures Miracle from most pet stores and some larger market pet sections. This chemical will neutralize most pest accidents quite quickly. If you use the black light at the same time you will see the green disappear in short order.
Once that is done a good cleaning using a rental rug cleaner you should be good to go.
Great tips so far.Here's a post by @Anna M that you might find useful: http://www.hometalk.com/722540/how-to-remove-urine-smell-from-carpet
Have you tried vineagar and baking soda ? there is a cleaner on the web site called Dr,Jon's if you send me an email to lambchops51 @gmail .com I will send it to you here .
Well the carpets have been cleaned by me. Rented steam cleaner called the "Rug Doctor" and it worked great (excellent suction) I purchased the Oxi Clean mentioned by Luci H. above. Thanks Luci. I can't believe how great my carpets look. Oxi even brightened my carpet. The urine smell was noticable when wet but we pre-scrubbed the stained areas with Oxi and also added Oxi to warm water and added in the tank.
Oxi has a very nice smell. Cleaned Saturday and the house is dry now. So glad it's done and cost $32.00 plus $8.00 for (2) Oxi clean containers. Did my whole house for $40.00 Wow !! That's what I call DIY'er Thanks for all the suggestions-some really great ideas.