Feline Hepatic Encephalopathy Study Guide

Overview and Clinical Importance

Hepatic encephalopathy (HE) is a metabolic neurologic syndrome characterized by neuropsychiatric abnormalities resulting from liver dysfunction or portosystemic shunting. In cats, HE most commonly occurs secondary to congenital portosystemic shunts (CPSS), although it may also develop with severe hepatic insufficiency from conditions such as hepatic lipidosis, cholangiohepatitis, or acute liver failure.

The pathophysiology centers on the liver's inability to detoxify ammonia and other neurotoxins, leading to their accumulation in systemic circulation and subsequent neurologic dysfunction. Early recognition and appropriate management are essential for optimal patient outcomes and represent a commonly tested topic on the NAVLE.

Etiology and Underlying Causes

Congenital Portosystemic Shunts (Most Common)

Congenital portosystemic shunts represent the most common cause of HE in cats, with a reported incidence of approximately 2.5 per 10,000 cats in referral practice. These abnormal vascular connections allow portal blood to bypass the liver and enter systemic circulation directly, preventing normal hepatic detoxification.