Complete Guide to Hepatic Encephalopathy (HE) Symptoms and Dietary Management

Liver HealthQ&AMeongsiljang Veterinary Advisory Board

Hepatic encephalopathy is a neurological condition in which toxic substances affect the brain due to impaired liver function. Recognizing the symptoms and managing protein intake through diet are key to managing this condition.

What is Hepatic Encephalopathy?

A medical illustration showing the connection between a dog's liver and brain

Hepatic encephalopathy (HE) is a neurological disorder that occurs when impaired liver function prevents the proper filtration of toxic substances like ammonia, allowing them to affect the brain. Early detection is key. If your dog exhibits any signs such as staring blankly at walls, pressing its head against objects, or having a seizure, you should visit a veterinary clinic within 24 hours. This condition is particularly common in young puppies with portosystemic shunts (PSS) and in senior dogs with chronic liver disease.

Why Does It Occur? Main Causes

Hepatic encephalopathy occurs when the liver fails to properly detoxify ammonia by converting it into urea. There are three most common causes.

Portosystemic Shunt (PSS): Abnormal blood vessels bypass the liver, allowing toxins to flow directly to the brain. This is often a congenital condition in small-breed dogs.

Chronic Liver Failure: Prolonged liver cirrhosis or hepatitis leads to a decline in detoxification capacity.

Acute Liver Injury: Sudden damage to liver cells caused by ingestion of xylitol, certain medications, or toxins.

Symptom Checklist — Is My Dog Okay?

Symptoms of hepatic encephalopathy progress in stages and may worsen after protein intake.

Mild stage: Lethargy, decreased appetite, dull eyes

Moderate stage: Disorientation, head pressing against walls, excessive drooling, vomiting

Severe stage: Seizures, hindlimb ataxia, decreased consciousness, coma

Postprandial exacerbation: A pattern in which symptoms intensify after meals containing protein

Intermittent: Symptoms that come and go

If two or more of these signs are present, testing is recommended.

Photos of a dog with hepatic encephalopathy pressing its head against the wall

Emergency Signs Requiring Immediate Veterinary Attention

If any of the following symptoms appear, you should go to a 24-hour emergency animal hospital, even in the middle of the night. • Seizures occurring two or more times or lasting longer than five minutes • Clouded consciousness or unresponsiveness • Inability to stand on the hind legs and staggering • Vomiting accompanied by persistent head pressing • Convulsions suspected after ingestion of xylitol or other toxic substances Seizures caused by hepatic encephalopathy can lead to brain damage, so immediate emergency treatment is necessary as soon as symptoms appear.

How Is Diagnosis Made?

Diagnosis is made using a combination of blood tests and imaging studies. Hepatic encephalopathy is not diagnosed based on a single value; rather, it is confirmed when three criteria are present simultaneously: neurological signs, hyperammonemia, and abnormal liver function.

Fasting ammonia measurement: Hyperammonemia exceeding the normal range is an important clue. However, ammonia levels do not always correlate directly with the severity of symptoms, so liver function and neurological signs must be evaluated together.

Bile acid test: Liver function is assessed by comparing fasting and postprandial (2-hour) serum bile acid levels.

Blood chemistry panel: ALT, AST, albumin, and BUN levels are evaluated.

Abdominal ultrasound or CT: These imaging modalities are used to identify the location of portosystemic shunt vessels.

MRI: This helps differentiate cerebral edema from other neurological conditions.

Treatment options, including medical management or surgical intervention, are selected based on the test results.

Step-by-Step Comparison of Dietary Management for Hepatic Encephalopathy

Item	Mild stage	Moderate	Severe / recovery period
Protein source	Mainly dairy, eggs, and tofu	Small amounts of tofu and dairy	Prescription medical diet only
Protein ratio	Adjust per veterinarian's instructions	Adjust per veterinarian's instructions	As directed by the veterinarian
Feeding frequency	3–4 small meals per day	4–5 small meals per day	Per prescription diet guidelines
Foods to avoid	Red meat, fish, organ meat	All red meat, fish, and organ meat	All high-protein feed
Additional management	Lactulose syrup	Lactulose + antibiotics	Inpatient management

As of 2026, adjustments must always follow your attending veterinarian's instructions

Key Dietary Management Tips You Can Do at Home

Dietary management is a crucial component of caring for hepatic encephalopathy, with the primary goal of reducing ammonia production. Prioritize plant-based and dairy proteins: Tofu, egg whites, and cottage cheese produce less ammonia than red meat. Avoid red meat, fish, and organ meats. Feed small, frequent meals: Divide daily intake into 4–5 meals to reduce gastric burden and prevent sudden spikes in blood ammonia levels. Ensure adequate fiber intake: Dietary fiber promotes the excretion of nitrogen through the intestines and reduces ammonia absorption. Fiber-rich vegetables such as pumpkin and sweet potatoes can be beneficial. Lactulose syrup: If prescribed, administer 2–3 times daily. The appropriate dose is the amount that softens the stool.

Photo of a tofu, egg, and pumpkin diet for dogs with hepatic encephalopathy

Things to Absolutely Avoid

The following actions can rapidly worsen symptoms in dogs with hepatic encephalopathy: • Free-feeding jerky, chew treats, or meat-based snacks (high-protein overload) • Feeding salty human foods or canned tuna • Ignoring constipation (increases ammonia absorption from the intestines) • Adding supplements or medications without veterinary prescription • Skipping meals and then feeding a large amount all at once If seizures occur, contact your veterinarian immediately to adjust the diet and feeding method accordingly.

Treatment and Long-Term Management — When Surgery Is Needed

Treatment varies depending on the underlying cause.

Medical management: Lactulose combined with antibiotics (such as metronidazole) is used to suppress ammonia production in the intestines, along with maintenance on a prescription diet.

Surgical intervention: Congenital single portosystemic shunts are often curable through procedures that block the abnormal vessel, such as cellophane banding. Your veterinarian will determine the specific method and timing based on your pet’s weight and the location of the vessel.

Even after surgery, it is essential to continue the prescription diet as directed by your attending veterinarian to ensure a stable recovery. If the underlying cause is chronic liver disease, lifelong dietary and medication management will be necessary.

A veterinarian examining a puppy with hepatic encephalopathy

Reviewed by a veterinarian

Dr. Tony — Punnawat Phongkittirak

Veterinarian

A veterinarian who majored in veterinary medicine at Khon Kaen University, Thailand, and completed the IVSA program at North Carolina State University in the United States. Drawing on clinical experience at animal hospitals, he works in the pet healthcare field and is dedicated to building a digital care environment that connects pet parents with veterinarians.

Frequently Asked Questions

Can dogs with hepatic encephalopathy be completely cured?

It depends on the underlying cause. In cases of congenital portosystemic shunt, surgery often leads to a complete cure, whereas chronic liver failure requires lifelong management. With early diagnosis, your pet’s quality of life can be maintained at nearly normal levels.

Is it okay to continue feeding regular pet food?

If your pet is showing symptoms, regular food may have too much protein. Switch to a prescription diet for liver disease (e.g., Hill's l/d, Royal Canin Hepatic). If there are no symptoms and the prognosis is good, your veterinarian may allow a low-protein regular diet.

Does lactulose need to be given for life?

Once the underlying cause is effectively managed and ammonia levels stabilize, the medication can be tapered or discontinued. However, in cases of chronic liver failure or non-surgical portosystemic shunts, lifelong treatment may be necessary. Never stop the medication without veterinary guidance.

What first aid can I do at home during a seizure?

Please do not attempt to pull out your pet’s tongue; simply clear away any objects around their head that they could bump into. Applying honey or syrup to the gums during a seizure is not recommended due to the risk of aspiration. Since a veterinarian needs to perform a comprehensive assessment, including checking for hypoglycemia, please transport your pet to the clinic immediately once the seizure has stopped.

Which breeds are more prone to hepatic encephalopathy?

Yorkshire Terriers, Maltese, Miniature Schnauzers, and Poodles are known to be predisposed to congenital portosystemic shunts. If you notice growth delays, seizures, or abnormal behavior after meals in these breeds, it’s a good idea to have your pet undergo liver function testing.

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References

[1] Ettinger SJ, Feldman EC, Cote E. Textbook of Veterinary Internal Medicine, 8th Ed. Chapter on Hepatic Encephalopathy.

[2] Silverstein DC, Hopper K. Small Animal Critical Care Medicine, 3rd Ed. Hepatic Encephalopathy.

[3] Nelson RW, Couto CG. Small Animal Internal Medicine, 6th Ed. Hepatobiliary Diseases.