Praying for Belle

Our oldest puppy Belle (12 years old next month) gave us a big scare this morning. She was having trouble breathing and she was weak and disoriented. SLH took her to our Vet and when he handed her to the technician he told her that he thought that she just died. They took her back and started giving her oxygen and checking her out. We talked to her doctor around lunch time and she said that Belle is doing much better. She had a lot of fluid on her lungs and her heart was enlarged. They are going to run some more test on her this afternoon and see if they can figure out what caused this.
We feel a little better now but we still don't know what this means for Belle. Obviously we don't want her in pain and we don't want to keep her alive if she is in pain. She almost died last year on the operating table for some liver problems so we know there is not a lot they can do for her at this point because of her age and poor health. She only weighs about 6 pounds but she is fighter and has already been through a lot.
We got Belle when she was 6 weeks old. We had been married 2 years, so she was our first little baby. We've been through a lot with her. We didn't realize at the time but she came from one of those puppy farms and doesn't have the best genetics. She has had a lot of health problems over the years and we have spent many of dollars on surgeries but we would do it all over again. She is very loving and one of the smartest dogs I have ever had, and I have had many of dogs throughout my life. My family and SLH's family are both big animal lovers. We both grew up with several pets during our childhood and knew early on after we got married that we wanted pets. They are a lot of work but the unconditional love and joy that they bring to a family is so worth it. Unfortunately we know that most likely we will out live our pets and loosing them is very hard.
We are praying for you "our little Belle"!