Jack Russell liver function trouble

My 9 1/2 year old Jack Russell’s albumin level has been dropping slightly for a few years but last month it dropped to 2.1 per blood test. I had a bile function done last December and it was good. The vet recommended an ultrasound a few weeks ago, which showed a smaller liver light gray in color. The bile test was also given again and this time it showed a decreased function but no active liver damage. She had IBS issues years ago but was doing well on ZD dry food and 1/8 teaspoon tylan powder given once a day. She eats well, runs around, and doesn’t look sick but I am worried because the vet said they thought it could be cirrhosis of the liver. He mentioned I could try giving her Denmarin or have a laparoscopic biopsy done of the liver and intestines. I want to try to help her but I don’t know if making her go through the biopsy is a good idea. He also said if it is cirrhosis that nothing can be done to help her. What do you think? Do you think it would be worth trying Denamarin.