Case 13

In the past, the consensus has been to treat all of these patients surgically since prolonged altered blood flow through the liver may ultimately result in liver atrophy and clinical illness. For patients that cannot tolerate complete ligation or for clients with financial constraints, long-term medical management may be an option. Even if surgical correction is chosen, a period of medical management may be indicated to decrease the risk of perioperative complications.

A recent retrospective study evaluated 597 dogs with congenital or acquired shunts over a 30-year period.1 The study found no survival difference between surgically or medically treated dogs regardless of shunt type (intrahepatic vs. extrahepatic), although dogs with acquired shunts had a significantly shorter survival time than medically treated dogs with extrahepatic shunts, and dogs with intrahepatic shunts had a shorter survival time overall.

You think Olivia is a good candidate for surgery, and cystotomy to remove the uroliths can be performed at the same time. You discuss medical and surgical care at length with the owner, and she opts to take Olivia home and think about which treatment to pursue.

You caution Olivia's owner about the risk of urethral obstruction and review signs of worsening hepatic encephalopathy. Your discharge instructions for the owner are to feed Olivia a protein-restricted diet (e.g. Hill's Prescription Diet l/d Canine Hepatic Health, Purina Veterinary Diets NF Kidney Function Canine Formula, Royal Canin Veterinary Diet Hepatic Formula) and administer lactulose (0.5 to 1 ml/kg orally every six to eight hours) and neomycin (22 mg/kg orally every eight hours).

QUESTION 6

Lactulose is useful for treating patients with hepatic encephalopathy by producing all but which of the following changes in the gastrointestinal tract?

a) It alkalinizes the stomach contents to prevent absorption of acid.

b) It acidifies the enteric lumen and traps ammonia, which can then be eliminated with the feces.

c) It decreases activity of bacterial ureases.

d) It increases nitrogen tolerance.

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