Another suggestion to try is take a ball or other object that you can throw in front of the dog. All dogs have the trait of chasing something, even the highly bred shih tzu. Throw the object, or let it roll just in front of the dog for a few feet, and let her chase it down. Retrieve the object and continue the process. She should soon gain enough interest to pursue the object longer distances, while still on the leash (one of the "extendable" ones would come in handy at this point)... Additionally, while still on the leash, carry her to where other dogs have urinated. She should sniff and mark the area and the next time she should seek out that area again... Best of luck!