High Enzyme levels in my chihuahua

Question
I have a 2 year old Chihuahua who seems perfectly happy. He eats, he pees, he poos, he plays, he seems very normal. About 2 months ago, after an emergency room visit for an unrelated issue, I was made aware that my dog had slightly elevated enzyme levels. My vet ran him through all the non-invasive test and everything came back normal except his bile acid pre and post tests (his pre test was normal, but his post test was 3 points higher than it should be). We did an ultrasound, and the vet saw nothing totally abnormal, just that his liver was alittle small. Now my vets wants to do a liver biopsy, which is not cheap! We are trying an antibiotic and liver diet for a month to see if there is any change first, but if not, he wants to proceed with the liver biopsy. My concern is how much stress should I put on the dog with all these tests if he is showing no symptoms and seems very happy?? If it ends up being something serious, do you have any clue if a little dog (4 1/2 pounds) can survive a surgery of this magnitude with a good prognosis? Thanks for your time! Any help is appreciated!

Answer
Hi Leslie!
Please keep in mind that this is my personal opinion, but there is NO WAY I would put my little chi through that!  For one thing, he may live a normal life with no problems at all.  The thing is, even if he they found something....
which I think if there was anything they would have seen it in the ultrasound, but even if they did.... what would you do?  Replace the liver?  I doubt that would be an option!  And you bring up a good point too... would your little dog survive the surgery?  Maybe not!  The stress for one thing would be hard on him, and the surgery could kill him.  My advice is to do nothing. Go ahead and try the new diet, but if it were me, no matter what the results show, I would absolutely do NOTHING surgical. If it were a tumor, then maybe... but I really think that would have shown up already.  
Here's something else to think about.  I, personally, had high liver enzyme levels. My doctor did a biopsy on me too, and found nothing. I had tons of tests done.... with nothing showing up. He finally decided that my body just naturally has elevated enzyme levels. That was ten years ago, and just recently I had blood work done, and the enzyme levels are now normal.  Now, I know there is a difference in a dog and a human, but doesn't it make you wonder?   They did ultra sounds on me too, and couldn't find anything.  The biopsy showed nothing.  PLUS, I had insurance!  You don't on your dog, do you?  That would cost you a fortune and I bet you have already spent a lot.
In my opinion, I would say no more testing!  
God Bless,
Becky