2 year old Yorkie possible liver shunt?? Help Please if you have experience with this!?

She's just started having spells where she's wobbly, throws up and has an involuntary bm. Lasts just a couple minutes. Vet said this was a seizure, did a liver profile and said it's possible it's a liver shunt from the numbers shown. The BA was 32 and then 103 after giving her what I believe he said was a karo type syrup? He said the only way now to tell if this is the problem is to do surgery to diagnose it. She's a healthy dog, has never had any problems. We did switch about 4 months ago to Beneful Dog Food. She was always before on a fairly expensive organic brand. I am now wondering if perhaps it's the food? Does anyone have experience with Yorkies and dog food making the difference? I don't know whether to do the surgery or not.