Therapeutics

Hepatic encephalopathy requires quick intervention and can be managed with nil per os, intravenous fluids, lactulose (oral or per rectum), and anticonvulsants as needed to control seizure activity.

The biggest decision in patients with PSS is whether or not to have surgical cor­rection. Surgery, however, is not an option for all patients or if there are cost con­straints. Patients with primary portal vein hypoplasia or acquired shunts cannot be managed surgically and the correction of intrahepatic shunts is more technically difficult and requires advanced imaging equipment and skills for surgical correction.

A few long-term studies have been performed on patients with medical manage­ment alone. On average 50% of patients were euthanized within a year of diagnosis, but this does depend on the type of shunt. Surgery can have up to a 90% success rate in patients especially patients with extra­hepatic shunts (Greenhalgh et al. 2014).

Medical Management

Diet

Dietary protein should be restricted to the point where the patient's metabolic requirements are met without aggravating hepatic encephalopathy. The protein should be of high quality and readily digestible with dairy and plant protein better tolerated than animal protein. A high carbohydrate and moderate fat content diet can be considered especially if the patient is prone to hypoglycemia or hyperam­monemia. Feeding smaller meals frequently helps to reduce fasting hypoglycemia and serves to increase protein tolerance. Including a moderate amount of dietary fiber has been shown to be advantageous as soluble fiber reduces availability and production of nitroge­nous waste products by the gut. Insoluble fiber on the other hand helps bind toxic substances.

Oral Lactulose

Oral lactulose helps to decrease the pH in the colon and converts ammonia to ammonium, which is poorly absorbed. Dose is 0.2-0.5 ml/ kg TID. Aim is to produce soft stools and not diarrhea. Decrease dose if diarrhea occurs.

Antibiotics

Antibiotics can assist in decreasing bacterial colonization. Amoxicillin, metronidazole, and cephalosporin are most commonly used for 2-4 weeks. If using metronidazole lower the dose to 7.5-10 mg/kg BID due to hepatic metabolism.

Expected Outcome

Long-term prognosis for patients on medical therapy alone is guarded to poor. The long-term prognosis in patients with extra-hepatic shunts post-surgery is good if there are no complica­tions associated with surgery. In cases with intra-hepatic shunts, the prognosis depends on the surgical success rate with a complication rate as high as 75% reported. Cases with pri­mary portal vein hypoplasia can do very well with medical management. In cats as discussed the prognosis remains poor even post-surgery especially if neurological signs occur.