Hello, my name is***** and I have over 20 years of experience as a veterinarian. I am sorry to see that you have been waiting a while for a response. Your requested expert was not online and thus your question just came up for the rest of us to tackle. I'd like to try and help.
I understand that Coco is vomiting often, is losing excessive amounts of protein in her urine, and seems to have intestinal and kidney disease.
With the history that you have given me I would be concerned that your girl is suffering from a chronic disease process called protein losing enteropathy/nephropathy. That means both her kidneys and her intestines are diseased such that she cannot properly digest and absorb the foods she eats and is losing blood proteins through her diseased intestines and kidneys. This allows fluids to leak out of circulation and eventually causes a swollen, fluid filled abdomen. These pups will often vomit excessively and have loose stools. This disease is one most commonly seen in younger female Soft Coated Wheaten Terriers and their mixes but it can be seen in any breed.
I know that you have spent quite a bit of money already and lots of testing has been done, but you weren't specific about what has been done so far.
Tests which can help diagnose the conditions are measuring blood albumin and globulin levels (both are likely to be low), measuring levels of fecal alpha1-protease inhibitor (API) concentration (should be high), and comparing the levels of protein loss compared to creatinine loss in urine (should be higher than usual.
A definitive diagnosis is achieved via biopsies. Unfortunately with this disease we cannot cure them, we can only try to manage the disease and the symptoms it causes. This is understandably frustrating for many owners. Sometimes in spite of doing all the right things our patient's disease progresses at a fast rate, and it seems that we cannot turn things around. But there are things that we can try.
It may help to feed a hypoallergenic hydrolyzed diet and give drugs to decrease protein loss via the kidneys and hypertension (Enalapril or Benazepril). Steroids may be indicated as well.
Another possible cause of her condition is a portosystemic shunt, which is an abnormality in the blood vasculature that feeds the liver. The liver is responsible for making blood proteins and if function is poor and proteins aren't produced then we can see low blood protein levels, free fluid in the abdomen, and vomiting and diarrhea. This is usually a congenital condition, meaning that they are born with it, and symptoms may take time to develop in less severely affected dogs.
If her liver appears small and her liver function is abnormal (abnormal bile acids test) then a portosystemic shunt (congenital abnormal liver vessel anatomy) would be a reasonable tentative diagnosis. Then she would need further testing to determine the type of shunt (single or multiple vessels as well the location of the shunt - inside the liver or outside). Treatment will be determined by the type of shunt. If the shunt is a single one out side of the liver and can be successfully occluded without raising blood pressure within the liver then surgery to tie off or block the shunt is the way to go.
If the shunt is involving multiple small vessels within the liver or if when the shunt is occluded blood pressure within the liver rises then medical/diet therapy is the way to go.
I'll give you a link which discusses the different shunts as well as surgery and medical treatment which I hope will be helpful for you:
And here's another that is a little more about medical treatment:
It sounds to me like you do not have a firm diagnosis for your pup yet, and further testing needs to be done to determine the primary cause of her condition.
Please let me know if you have any further questions.