Oh I'm soo terribly sorry for what you are going through
We went through this with our Lassie (minature sheltie that we had for 17 years)...it was painful to watch her as she first lost her hearing, then slowly her eyesight went as well as her mind. My thoughts and prayers go out to you as I know Tina is a member of your family and watching them go through this is one of the hardest things