I'm sorry about Bella.
Honestly, I wouldn't have my vet contact them unless you need a referral.
They'd just be a middle man...
I would call them myself and set up a consult and possible surgery.
Has the Protein C test been done yet?
It could be MVD if that comes back normal.
Liver shunt can't be diagnosed with symptoms and high bile acids alone.
UT charges less than $2000 for surgery including spay.
This may also include some diagnostics.
They are the best (along with Cornell) anyway.
$5000 is waaaaaaaaaaaaaay too much and they should not be going to surgery without a positive diagnosis with something like scintography.