Sorry to hear about Buster.
Since 2 Shih Tzu are all I've had, they are the standard for me. I couldn't have dreamed up a better little dog to live with me. I read that they are slow learners or difficult to train. I could show them something 2 or 3 times and they got it.
So now I have my 13 year old Belle. She has an enlarged heart and a grade 4 heart murmur which causes fluid build up in her lungs. Meds are helping so far but taking it one day at a time.