A Surgery That Did Not Go As Planned

January 1, 2015Surgery
Author: David S. Thomson DVM

Nugget is one of the sweetest dogs around. When this young Lhasa was adopted from a local shelter, she was sickly — skinny, with a poor coat and chronic diarrhea. Although she was treated with multiple medications, pampered and loved, she continued to decline. Blood tests revealed an elevation of liver values. A more specific blood test confirmed the problem — a liver shunt.

A liver shunt is a congenital vascular anomaly. There are several different types, but the most common in small breed dogs is an extra-hepatic porto-caval shunt. In this condition blood coming back from the intestines, stomach or spleen bypasses the liver (where it is supposed to go to be detoxified) and enters directly into the systemic circulation. The result is toxin build up, causing diarrhea, weight loss and a condition called hepatic encephalopathy (mental dullness, especially right after eating, and seizures).

more-nugget-017_0Medication can help minimize absorption of toxic substances, but over time the condition progresses. Without surgery, dogs with liver shunts usually die young. Surgery to treat a liver shunt involves locating the abnormal blood vessel and closing it, allowing the blood to divert back to the liver. Sounds simple. Sometimes it is, and sometimes it isn’t.

The first challenge is identifying the aberrant vessel. You can inject radioactive isotopes and do a nuclear scan; you can open the abdomen and inject a dye in an intestinal vein and take radiographs; or you can ultrasound the abdomen using special Doppler techniques. In Nugget’s case, I had Dr. Peterson, a brilliant internist and ultrasonographer, scan the abdomen to locate the vessel.

The second challenge is closing the vessel once you find it. You cannot close the shunting vessel all at once. The liver is not able to accommodate a sudden increase in blood flow, so we use a device called an ameroid constrictor to slowly occlude the vessel. This constrictor is placed around the abnormal vessel, and then slowly over the next six weeks, it swells, compressing the vessel and ultimately closing it.

With the information from Dr. Peterson’s ultrasound, I proceeded with confidence. I have done this surgery often before without any problem. I found what I identified as the aberrant vessel and placed the constrictor around it. Nugget woke up nicely and went home the next day.

The plan was to recheck Nugget’s liver tests in 6 weeks. By then the constrictor should have completed its work. But six weeks later when we repeated Nugget’s blood tests, the liver values were worse. I could think of lots of reasons for this. Perhaps there were multiple shunts that we just had not seen. Or perhaps multiple new shunting vessels had opened since the surgery, or the constrictor had not closed properly, or the liver was just too diseased to recover. But most likely, and most worrisome of all for me, perhaps I had occluded the wrong vessel.

A follow-up ultrasound confirmed my worries. I had occluded an abnormally large but ultimately quite normal vein (the left phrenico-abdominal vein). The liver shunt was still there. I spoke with the owners and told them what we had found. And I asked them if I could try again. Thank goodness they said, “Definitely yes.” I re-operated on Nugget two days later, found the correct vessel (I was sure this time!) and applied a new constrictor.

A few weeks ago we repeated the liver tests, and they are normal.
Little Nugget looks and feels great!  We feel pretty great, too.

nugget-w-lee nugget-fall-2014

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