Our female Shih Tzu is 15 1/2 yrs old. She is blind and deaf but copes quite well with her disabilities. Over the last few weeks she is barking constantly for several hours for no reason at all. This usually happens in the evening and bedtime. When I put her on my lap she is usually ok for a few minutes but then wants down and it starts all over again. What can I do to stop/reduce the barking. Treats do not work during th ese episodes either.