Which option best describes hepatic encephalopathy in cats in terms of ammonia?

• A. Reduced ammonia levels
• B. Ammonia accumulation
• C. Biliary obstruction without encephalopathy
• D. Primary liver cancer

Answer: (B)

Hepatic encephalopathy in cats is driven by elevated ammonia in the blood due to the liver’s reduced ability to detoxify it. Normally, gut bacteria produce ammonia from dietary protein, and the liver converts this ammonia to urea for excretion. When the liver is damaged or a portosystemic shunt bypasses hepatic processing, ammonia accumulates and crosses into the brain, where it disrupts neurotransmission and causes neurologic signs. So describing it in terms of ammonia means recognizing that the problem is ammonia accumulation because detoxification is impaired. This is why reduced ammonia levels wouldn’t explain encephalopathy, and while biliary obstruction or liver cancer can contribute to liver dysfunction, the hallmark feature regarding encephalopathy is the buildup of ammonia.