Nope. None other than to get the Shih Tzu checked with a vet. Like lv4dogs mentioned, it's very possible the dog is losing her eyesight and/or hearing which can cause snappiness. Or, there could be another underlying health ailment like a dysfunctioning internal organ and/or arthritis. Oldies need special care, but they blossom once you've got the basics down I love seniors and I wish her the best of luck.