My 13-year-old tuxedo, neutered male cat, has had elevated liver enzymes for approximately 1 year. Originally, I brought him in because he was pooping in the middle of the living room in the spring of 2025. This was chalked up to a behavioral issue, since I had moved his litter box downstairs. I moved it back upstairs after a few weeks, and eventually he stopped. Lately, however, he has started again every other week or so, and has had diarrhea for the last 3 days. I have given him Forti-Flora, so I will continue to monitor that. I believe the pooping issue is behavioral, since he is a highly demanding cat and wants to go on his leash outside and eat grass, and is upset that he doesn't get to do so due to cold and rain.
Anyways, the main issue is that in April of last year (first image) when I first took him in for this pooping issue, his blood work came back with high liver enzymes.
He was given a regimen of SAMe and Ursodiol, and tested again in September 2025 (second image).
SWe kept him on this regimen, tested again in December, decided to add Prednisone in February of this year, and I am now waiting on his blood work results as of today.
My vet has been suggesting a liver biopsy, but I am hesitant to go through such an invasive procedure since his overall disposition is normal. He is active, playful, drinks water normally, and is always excited about food. Also, they quoted me $6,000 for the liver biopsy, which is incredibly expensive, but I would do it if he were exhibiting any other signs of distress.
My veterinarian said that this is likely the last pill regimen we can give him without performing a biopsy. We have conducted ultrasound and X-rays on him, and everything has come back mostly normal, though a very mild increase in heart muscle thickening was observed in the summer of 2025. He is due back for another ultrasound in July.
What do you think the best course of action would be?