2yr old shih tzu female soiling carpets suddenly

Question
I have a 2 year old shih tzu female.  She is an outstanding dog with lots of personality.  She was spayed at 10 months and in the past did VERY WELL with poddy training.  She was trained within 2 days to relieve herself on wee wee pads.  She has been consistently doing well up until recently.  She has been spoiling the carpet RIGHT NEXT TO the wee wee pad which is clean.  And this behavior occurs only when I am not present in the home.  I allow her to roam around in my room because she does not have any destructive behavior.  She is a very good dog, except only in this aspect.  I tried many different tactics and none of them seem to work.  I tried reteaching it to her - praising her/giving her treats when I catch her doing it right - or when i come home and see that she has done a good job.  I tried completely ignoring the behavior and her when she spoils the carpet so that she doesn't correlate it to negative attention.  I tried giving her more room so she can roam around the whole apartment to decrease stress.  I'm just not sure what to do anymore.  I'm tired of cleaning the carpets everyday and would like to resolve this problem.  Do you know of anything I could possibly try?  Some people have suggested crating her, but I would not like to resort to that.  PLEASE HELP!!! thank you!!!

Answer
The problem with wee wee pad training is that you are rewarding the dog for eliminating INDOORS.  This often causes generalization, which is occurring here.  Going ON the pad is soon replaced (accidentally at first) by going NEAR the pad.  The dog doesn't know the difference.

Move the pad to an area with tile or linoleum; confine the dog to that room when you are not home.  Allowing her to roam your living space might seem "kind" to you, but to the dog it's an enormous responsibility.  She will not suffer from being confined to the kitchen (or even a good sized bathroom) with a baby gate.  Repeatedly take her to the new location, reward with praise and small food treat when she eliminates there (much as you would if you were training her to go outdoors) and give her some time to make the adjustment.  This is rather like reintroducing house training to a dog following a physical move of the household.  Until then, prevent her from going into the room where her pad is now (unless you are present and you must watch her closely), especially since the carpet is soiled.  You might successfully eliminate the smell of urine for yourself, but no matter what you do the dog will always pick up the scent (their sense of smell is 100 times -- at least -- more acute than ours.)

Unfortunately, generalization can be a big problem when one uses wee wee pads, so you are likely to see this behavior repeated.  That's why it's best to put the wee wee pad in a place where soiling the floor can easily be remedied and the scent successfully extinguished.