I know what your going through, went through the same thing myself a few years ago with a dog. We went the chemo route.....all was well for a year (couldn't tell he had cancer at all) then it was time for the chemo to stop. He was well for a few months........then went downhill fast. We knew someday it would be like that.......was hard watching a over 100 pound dog lose so much weight in a matter of weeks. We had to make the decision to put him down. I still think we made the right choice with the chemo...gave him extra "quality" time but he didn't have to go to the vets weekly either. We would go and get the pills....he went every month and it was a big deal to him........he loved going. He had leukemia, no tumors or fluid buildup. I'm really sorry for the decision you have to make, it's hard.