I am pretty sure the reason your vet is so certain that your baby has a liver shunt is because of the stones...The type of stones that liver shunt dogs produce are ammonium urate and are NOT seen on x-ray and are ONLY seen on ultrasound....Of course, liver shunt can't be diagnosed only from that, but like I said, that's a VERY good indicator...
The only dogs that produce ammonium urate stones are Dalmations and dogs with liver shunt/disease...
Many times, these stones are the only symptom of liver disease...Does your baby exhibit any symptoms other than the bladder stone issues?
Picky eating? falling over? acting drunk? drooling? vomiting? etc?
Do you have any lab values? You should get copies of all of that from your vet.
Liver disease is not a death sentence, and many liver compromised dogs have had surgery. My yorkie has had a total of 3 surgeries (I think...), and he is still alive
You just have to provide maximum liver support and make sure they use the RIGHT anesthesia and be very, very careful with pain meds...