Liver disease and diarrhea?

Hi Dr. Marie
My 11 y.o. Boston Andi (about 14 pounds) has been a healthy girl all her life. The only thing she's ever had has been occasional diarrhea, maybe once or twice a year, sometimes years go by without even that. Andi had a short but severe bout of diarrhea about 2 1/2 months ago. Middle of the night, blood, awful. I fasted her and fed very bland stuff, and it was not so bad but not resolved completely in 2 days so we went to the vet. She did a blood test and discovered elevated GGT and Total Bilirubin and low protein (I have scanned all results and will try to email to you.) She gave her a B12 shot, and we started her on Metronidazole (125 mg 2x daily) and Denamarin. Andi was completely recovered and normal acting. We went back for a follow up (again no fasting) blood test and Bilirubin was up from .6 to 1.3; GGT up from 17 to 47. The doctor recommended a liver biopsy.

I took Andi down to my sister's place for a week to see her vet for a second opinion, as my sister has great respect for him. We saw somebody different. A bile acids test was done, an ultrasound and blood tests repeated. Bile acids pre:6.6; post 54.1. Ultrasound showed enlarged adrenals, with sludge seen in gallbladder. Cushing's was ruled out after an LDDS was normal. Recommended food change which I did. No other hypotheses. Told me to see local vet and get a urine test for creatinine/cortisol ratio. Local vet puzzled by Cushing's hypothesis and urine analysis. An ordinary urine analysis was done. NEW blood work and bile acids test showed GGTP at 20;Platelet Count 423; Pre meal bile acids 23; post meal bile acids 29.9. Liver biopsy was attempted but abandoned as the liver was quite vascular and the procedure deemed unsafe.

It has been 2 1/2 months since the diarrhea that started all this and yesterday I began to notice the symptoms of another attack starting -- gas, esp. at night, getting BAD, is the big sign. she's not a gassy girl ordinarily. The next day sure enough, there was diarrhea, but it wasn't the explosive kind. I fasted her and started her back eating slowly, while starting her on 125mg. of metronidazole morning and night, plus a famotidine before bed because she seems to have acid reflux as her tummy gets emptier. This morning stool is pasty but formed, and she eats well (always!) and gas disappears after eating. I will try to send the scans of test results; please don't display these. I don't know what to do -- whether this bland canned food is doing something, or I should keep her on metronidazole forever or what. Any thoughts? needless to say I love this dog, and don't want to put her through treatments that have little chance of helping, at her age. I would appreciate your thoughts. Thank you very much for reading all this. Kathleen

Thank you Dr. Marie
I appreciate your prompt and thorough answer. I will follow up with my local vet re tylosin and IBS.

Is there a test for IBS? Is it undesirable to continue very long on the metronidazole? And is there a food you would recommend, or types to avoid? I was also wondering if smaller, more frequent meals would be helpful. Sorry about all these questions! I won't abuse your good nature any further. I am grateful for your "voice in the wilderness" so to speak. Many thanks for a much needed service.
Kathleen