A 2-year-old, male castrated Labrador Retriever was presented to Cornell’s Emergency Service for evaluation of a several day history of abnormal mentation and inappetence that progressed to an obtunded mental state. The patient was previously diagnosed with an intrahepatic portosystemic shunt and had been successfully medically managed for two years.

On presentation to Cornell’s emergency room, the patient was laterally recumbent, obtunded, and dysphoric. He was tachycardic with bounding pulses, tachypneic, and had an elevated temperature. Melena was noted on the rectal thermometer. Point of care bloodwork revealed a mixed acid-base disturbance, hypernatremia, hyperchloremia, and hyperlactatemia. An intravenous catheter was placed and a fluid bolus reduced the patient’s heart rate and rectal temperature to within the normal range. The dog was hospitalized and his care was transferred to the Critical Care Service.

The patient’s mental state progressed to intermittent head-pressing, ataxia, and circling followed by periods of profound obtundation. Neurologic examination revealed an inconsistent menace response. Intravenous mannitol was administered, as well as broad spectrum antimicrobials. Both oral lactulose and lactulose enemas were instituted, and gastroprotectants and anti-emetics were administered. An abdominal ultrasound confirmed the presence of an intrahepatic portosystemic shunt, as well as bilateral renomegaly. Complete bloodwork revealed moderate thrombocytopenia, elevated liver enzymes, and an elevated serum ammonia level consistent with hepatic insufficiency. Serial bloodwork demonstrated a regenerative anemia. Due to the anemia and melena, gastrointestinal hemorrhage was suspected to be the acute inciting cause of hepatic encephalopathy.

Over the next several days, the patient’s mentation improved markedly in response to treatment. His anemia initially worsened and then plateaued, though he developed polyuria/polydipsia and profuse diarrhea. The enemas and intravenous therapies were discontinued and his care was transferred to the Internal Medicine Service. He was discharged to the care of his owners after three days in the hospital.

This seminar will discuss the etiology, pathogenesis, management, and prognosis for hepatic encephalopathy secondary to portosystemic shunts.