L.A.
We lost our 11 1/2 year old Husky last June to liver cancer. He was drinking a large amount of water, not sure how his urine looked since he went potty outside on his own. Our clue was excessive water intake and high liver levels. Since we had adopted him at age 9 we had no baseline to go on and the blood panel we had run when we got him showed high liver levels, which the vet monitored. We were about to put him through a third surgery for soft tissue sarcoma on his torso when she recommended an x-ray of his liver first, again because his liver levels were higher than they had been in the past. Sure enough, his liver was full of tumors, non operable. He had probably had them for years, which I'm told is pretty common.
Have your vet run a complete blood panel. If that's not definitive go for the x-ray.
I wish you luck with your precious girl. I know how heart wrenching this can be. Please let me know how things turn out.