a plasma transfusion is when it is real severe as my dog had it as he was on deaths door
it flushes the toxins out of the body as the pancreas makes the blood toxic - they have to sedate and do fluids through the jugular so it is very expensive to sedate and do all that but i almost lost him
50% of dogs die when they get pancreatitis so it is very serious and nothing to mess with
call and ask the er if they have the snap in house cpli test and ask your vet the same as the cpli test takes 3-4 days to come back from lab and the in house is instant so it will confirm pancreatitis but i think it is from what you are describing