The Ultrasound is up to you. Me, I'd do the BAT and bloodwork and urinalysis first. The U/S I believe is only 60% accurate, and the person reading it also has to be very, very skilled and experienced with U/S.
I did one on Roxy it cost about $300 and what it told us was her liver was of normal shape and normal size. No shunt was seen...BUT...they could not tell me 100% there was no shunt and a U/S will NOT show mild cases or major cases of MVD. So, just be prepared for that and more further testing.
Being that you are in NJ you may want to connect with the ppl on the liver disease site:
DogLiverDisease : Dog Liver Disease