Liver Shunts

How are liver shunts diagnosed?

Diagnosis is based on medical history and clinical signs. Common diagnostic tests include:

• Complete Blood Count (CBC) and Serum Chemistries. Typical abnormal findings include mild anemia or smaller than normal red blood cells (microcytosis), low blood urea nitrogen (BUN) and albumin, and increases in liver enzymes (AST, ALT).
• Urinalysis. Urine may be dilute (low urine specific gravity) or there may be evidence of infection. The urine may contain small spiky crystals known as ammonium biurate crystals.
• Bile Acid Test. Most dogs with liver shunts have elevated bile acids. If the bile acids are mildly increased, or if the dog seems clinically normal despite abnormal test results, the tests will often be repeated in three to four weeks.

Once your veterinarian suspects a liver shunt, you'll likely be referred to a specialty veterinarian for a CT scan or ultrasound.

Church of Pug has had excellent results at Summit Veterinary Referral Center for liver shunts in pugs.

What are bile acids?

Bile acids are produced in the liver and are stored in the gall bladder between meals. Normally, they are released into the intestines to help break down and absorb fats, after which they are reabsorbed by the portal system and enter the liver, where they are removed and stored again until needed. Dogs with liver shunts have increased bile acid concentrations in the blood because the liver does not get a chance to remove and store these chemicals after they are reabsorbed.

Tests that measure the amount of bile acids in the blood are used to screen for liver shunts. To perform this screening test, two samples are usually taken. The first sample is taken after fasting (pre-prandial). The second sample is usually taken two hours after being fed (post-prandial). The actual technique may vary based on the patient and on your veterinarian's preferences.

How are liver shunts treated?

Dogs with liver shunts are treated with special diets and medications to reduce the amount of toxins that are produced and absorbed in the large intestines. At times, dogs with a liver shunt can become critically ill and require intravenous fluids to stabilize blood sugar, an enema to remove intestinal toxins before they are absorbed and medications to stop seizures.

The most common medical treatment regime includes:

• Diet Change. The goal is to reduce the amount of protein in the diet and feed only high quality, highly digestible protein diets.
• Lactulose. Administering this sugar changes the pH in the large intestines, which decreases the absorption of ammonia and other toxins and makes the intestinal environment unfavorable for toxin-producing bacteria.
• Antibiotics. In some cases, antibiotics are used to alter the bacterial population in the intestines, and to reduce intestinal bacterial overgrowth.

What is the prognosis for a dog with a liver shunt?

Most dogs improve almost immediately with proper diet and medication. About one-third of the dogs treated medically will live a relatively long life. Unfortunately, over half of the dogs treated medically are euthanized within ten months of diagnosis because of uncontrollable neurological signs such as seizures, behavioral changes, or progressive liver damage. Dogs that tend to do well with long-term medical management are usually older at the time of diagnosis, have more normal blood test values and have less severe clinical signs.

Dogs with a single shunt, especially one that is extrahepatic, have an excellent prognosis if surgical correction is performed.

Is there surgery for a liver shunt?

Surgery provides the best chance for a long, healthy life in most dogs with extrahepatic shunts. If ameroid constrictor placement is performed, survival rate is over 95%. Many dogs are clinically normal within four to eight weeks following surgery.

Most surgeons use a device such as an ameroid constrictor that slowly closes the shunt. The ameroid constrictor is a metal band with an inner ring of casein, a protein found in milk. In the abdomen, the inner ring absorbs normal abdominal fluid and gradually swells, pressing on the shunt and encouraging it to scar shut. Shunts usually close within three to four weeks after ameroid constrictor placement.

Other surgical treatments include 1) cellophane bands that induce inflammation, gradually closing the shunt with scar tissue and 2) intravascular occlusive, clot-inducing devices.

A small percentage of dogs will develop multiple acquired shunts and must be managed with a protein-restricted diet and lactulose for life.

What happens after surgery?

Your dog will be kept on a protein-restricted diet for minimum of six to eight weeks. After blood test values return to normal, your dog may return to a high-quality maintenance diet. Lactulose is usually given for several weeks after surgery.

The liver will begin to grow as the shunt closes and will often be normal size and function in two to four months. Blood tests will be repeated at regular intervals to evaluate liver function.

If my liver shunt dog must be kept on a protein restricted diet, what can I use for treats?

Liver shunt dogs get spoiled with the best treats - including blueberries, raspberries, carrots, gerber puffs, freeze-dried sweet potato treats and even whimzees!