Liver Shunts
Frequently Asked Questions
by Jay Bianco| Maltese Dogs Liver Shunts Frequently Asked Questions
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by Jay Bianco |
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What are the signs?
There can be a lot of variation of clinical signs depending of the severity of the condition,
which could depend on how much blood flow is diverted past the liver. Some of the clinical signs of portosystemic shunts that might be recognized in a puppy or young adult Maltese that have been reported could include:
Problems increasing dramatically after eating has also been strongly supported as an indication of a portosystemic shunt. Not all Maltese with the shunt will show this meal associated behavioral change, but in 25% of those affected that do, the diagnosis could become clearer. A high percent of affected Maltese show an intolerance to anesthetics or tranquilizers, & will show increased recovery times following their use. Approximately 75% of those affected will show digestive system symptoms including poor appetite, ascites, vomiting, drooling, diarrhea, or occasionally deranged appetite (eating paper, etc.). Urinary system symptoms may include increased thirst and urination, & in a majority of porto-systemic shunt cases, there will be crystals or stones formed in the urinary tract. These crystals will be either uric acid or ammonium urate (ammonium biurate or thorn-apple crystals.). Most Maltese will be diagnosed with port-systemic shunts under one year of age, but some several years older have been diagnosed with the condition.
How is Liver Shunt diagnosed?
There are a number of possible abnormalities that might point towards a portosystemic shunt on:
Acid levels are extremely important in the diagnostic screening of symptomatic potential shunts. Fasting and a two hour post meal blood samples are evaluated for bile acid
levels. In virtually all porto-systemic shunts there will be a significant rise in the bile acid levels over normal. The use of bile acids in screening clinically normal for liver shunts is not currently being advised due to the variation of normal bile acid levels in Maltese, and other breeds as well. Reports of recent vaccination with modified-live vaccines causing high serum bile acid levels in normal animals have not been confirmed as of this time.
Liver function testing with Bromosulfaphthalein (BSP) or ammonia tolerance testing are sensitive and reliable if performed correctly. These tests measure the liver's ability to excrete/detoxify known agents, and thus measure liver function accurately.
Routine performed serum chemistries are fairly nonspecific toward confirming the
diagnosis of porto-systemic shunts, but there may be a decreased total protein (primarily albumin), decreased blood glucose, decreased cholesterol, & decreased blood urea nitrogen (BUN). The uric acid levels may be elevated in a significant number of those Maltese affected.
Radiography is one of the most important methods of establishing a diagnosis of porto-systemic shunt, and is currently the only universally accepted method of confirming a shunt, short of major surgery. Injection of a radiopaque dye into the spleen (Splenoportograpy) will show the shunt on radiographs and allow accurate assessment for surgical correction. But this is a pretty invasive test making it a poor choice for "screening" purposes. Special dyes injected into the liver circulation that show up on X-rays can outline the problem pretty clearly. Most of the time. But this is a pretty invasive test making it a poor choice for "screening" purposes. There are a number of possible abnormalities that might point towards a portosystemic shunt on routine labwork, including low BUN (blood urea nitrogen), low albumin, mild anemia, increases in ALT (serum alanine aminotransferase) or ALKP (serum alkaline phosphatase). If these hints are present, it would be a good idea to test the serum bile acid levels prior to eating and after eating. If this test is supportive of poor liver function then it may be a good idea to consider ultrasonagraphy and dye contrast X-rays.
This procedure requires expensive equipment and the diagnosis is based on the distribution of the radionuclide in the lung or heart compared to that in the liver. The placement of a radioisotope specific for the liver into the colon for absorption through the mucosa has been gaining favor because of its noninvasive diagnostic value. This procedure also does not identify the exact location of the shunt for surgical correction if required.
Currently there is research using Color Doppler Ultrasound which could soon be the preferred screening and diagnostic tool. In the past, ultrasound was fairly unreliable for nonsurgical diagnosis of porto-systemic shunts.
How is it treated?
Surgery appears to be the only cure for portosystemic shunts at this time.
Is there a genetic predisposition toward Porto-Systemic shunts?
At the present time, according to the experts, yes, most definitely Hepatic Porto-Systemic shunts are a genetic disorder.
For more information on recognition and management of portosystemic shunts
