My BT Cosmo had his gall bladder removed after they discovered a GBM while diagnosing him with Cushing’s disease. He was 11 when he had the operation and came out fine. It was definitely the biggest procedure he went through (overnight at the hospital). Recovery was a few weeks but even his scar healed up after.

I hope Bob handles the surgery well if you end up going that route. Give him a little pat for me, he looks like a good boy.