What is hepatic encephalopathy?

Hepatic encephalopathy is a set of neurological and behavioural changes that occur when the liver fails to function properly, allowing metabolic byproducts to affect the brain. Signs include lethargy, behavioural changes, and vomiting. Consult your vet to identify the cause and appropriate management.

How does a vet diagnose hepatic encephalopathy?

Diagnosis typically combines clinical signs, blood biochemistry (including liver function markers and ammonia levels), urinalysis, and imaging. A liver biopsy may be arranged when needed to confirm the underlying cause — follow your vet's guidance on which tests to prioritise.

Can a pet fully recover from hepatic encephalopathy?

Recovery depends on the extent of liver damage and the underlying cause. Some pets show significant improvement with treatment and supportive care, while severe or chronic cases may require long-term monitoring. Follow your vet's assessment and recommendations.

What should I do if my pet shows similar symptoms?

If you notice lethargy, behavioural changes, persistent vomiting, or an unsteady gait, record the details of the symptoms and bring your pet to the vet promptly. Provide your observation notes and any videos to help with the assessment.

How much do the tests and treatment usually cost?

Costs vary by clinic and region — ask your vet for an estimate before proceeding.

Disease Guide

Hepatic Encephalopathy in Dogs & Cats: Symptoms, Liver Tests & Care Guide [2025]

Hepatic encephalopathy occurs when the liver fails to clear toxins (mainly ammonia) from the blood, causing neurological symptoms. Common causes include portosystemic shunts and chronic liver disease. Management involves a protein-restricted diet and medications to reduce blood ammonia levels.

Take 1 minute to check the symptoms first

Last updated: 2026/01/05

Pethealthmap Editorial Team

Sources: ACVIM, WSAVA, National Taiwan University Veterinary Hospital

When to See a Vet

Seek emergency care immediately

•Sudden onset of seizures or generalized convulsions
•Sustained deep coma or complete unresponsiveness
•Repeated vomiting with inability to stand or collapse

Schedule a clinic visit soon (within 24–72 hours)

•Persistent lethargy with noticeably reduced activity
•Intermittent behavioral confusion or sluggish responses
•Ongoing vomiting or diarrhea causing evident dehydration

01What symptoms signal a problem?

Early hepatic encephalopathy often presents as physical and behavioural changes that can fluctuate within a day — watch closely for neurological and digestive signs.

Altered mental status: lethargy, slower responses, or difficulty focusing
Noticeably reduced appetite or loss of interest in familiar food
Repeated vomiting or ongoing digestive upset
Diarrhoea or loose stools with changes in bowel habits
Abnormally increased thirst or urination
Decreased activity, slow movement, or unsteady gait

Seek emergency care immediately if you notice the following symptoms:

⚠️ Seizures or brief loss of consciousness
⚠️ Persistent vomiting accompanied by weakness or stupor
⚠️ Sudden extreme confusion or inability to stand

02How to assess the situation at home? Key home-monitoring and emergency criteria

Keeping detailed notes of what you observe at home helps the vet quickly understand how the condition has progressed — focus on specific times and frequencies.

Record the date symptoms first appeared and how often they occur each day
Measure and note changes in water intake and urine output daily
Log the number of vomiting or diarrhoea episodes, timing, and colour of the contents
Take short videos to document mental alertness, behaviour, and walking ability
Weigh your pet and note daily food type, amount, and appetite changes
If symptoms worsen, arrange a clinic or emergency visit promptly

03How will the vet diagnose the condition? Common diagnostic tests

At the clinic, the vet will carry out a systematic examination to identify possible causes and determine whether further treatment or hospitalised monitoring is needed.

Full physical examination

assessing consciousness, neurological responses, and degree of dehydration

Blood count and coagulation assessment

Biochemistry panel

liver enzymes, bilirubin, ammonia, and other liver function markers

Urinalysis

evaluating changes related to metabolism and kidney function

Imaging

abdominal ultrasound or CT scan if necessary

Liver biopsy

considered when the underlying cause cannot be confirmed

After results are available, specialist follow-up and a treatment discussion are recommended

04How is the condition treated and managed after diagnosis? Medications, diet adjustments & care guide

Treatment focuses on supportive care while addressing the underlying cause of liver deterioration — regular follow-up visits to monitor blood work and clinical status are essential.

Fluid therapy and electrolyte correction to restore body condition and maintain blood pressure
Appropriate medications and infection management based on test results
Low-protein or hepatic prescription diet to reduce metabolic burden
Monitoring and management of complications such as infection or metabolic abnormalities
Severe cases may require hospitalisation with oxygen support or intensive care
Schedule follow-up visits as directed to recheck blood and biochemistry values
If the condition recurs or fails to improve, referral to a specialist hospital is recommended

05What to prepare before seeing the vet? Key information to help the vet pinpoint the cause quickly

Note when symptoms started, how often they occur, and how they have changed

Record daily water intake, food amount, and type of diet

List vomiting and diarrhoea episodes, urination frequency, and stool consistency

Bring the current list of medications or supplements

Bring recent blood test results or imaging reports (if available) for comparison

Prepare a sturdy carrier with bedding and back up any videos to your phone

This content is for reference only and cannot replace a professional veterinary diagnosis. If your pet shows signs of illness, please seek veterinary care promptly.