What are the early signs of a congenital portosystemic shunt?

Common early signs include lethargy, reduced activity, repeated vomiting or diarrhoea, changes in appetite, and occasional seizures. If these symptoms persist or worsen, seek veterinary evaluation promptly.

What tests will the vet perform at the clinic?

Common tests include a complete blood count, biochemistry panel, and urinalysis, as well as abdominal ultrasound or CT to assess portal blood flow; cytology or biopsy may be arranged for further diagnosis if needed.

Does this condition always require surgery?

Not all cases require surgery; some can be managed medically with medication and dietary control to stabilise symptoms. Whether surgery is needed depends on the vet's assessment of imaging findings and overall condition — follow your vet's recommendation.

What long-term follow-up is needed after surgery?

During recovery or conservative management, regular monitoring of blood biochemistry, imaging, and clinical signs is required. Medication and diet should be adjusted per your vet's guidance, and regular check-ups are essential.

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

Congenital Portosystemic Shunt in Dogs & Cats: Symptoms, Diagnosis & Treatment [2025]

Congenital portosystemic vascular anomaly causing hepatic encephalopathy symptoms

Take 1 minute to check the symptoms first

Last updated: 2026/01/06

Pethealthmap editorial team

Sources: ACVIM, National Taiwan University Veterinary Hospital

When to See a Vet

Seek immediate veterinary care (emergency)

•Repeated or persistent seizures with loss of consciousness
•Sudden onset of prolonged, deep lethargy with no response
•Persistent severe weakness or inability to eat on their own

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

•Intermittent lethargy but still able to wake briefly
•Repeated vomiting or diarrhea lasting more than a day without improvement
•Noticeably increased water intake or a change in urination frequency

01What symptoms indicate something is wrong?

Pets with congenital portosystemic shunts often show non-specific but persistent systemic symptoms; early observation helps prompt veterinary evaluation.

Persistent or recurring lethargy, low energy, and reduced activity
Repeated vomiting or diarrhoea that does not resolve quickly
Noticeably increased water intake or excessive thirst (polydipsia)
Significant changes in urination frequency, volume, or urinary incontinence
Occasional seizures, brief loss of consciousness, or abnormal behaviour

Seek emergency care immediately if you notice the following symptoms:

⚠️ Repeated or continuous seizures require immediate veterinary care
⚠️ Sudden loss of consciousness or prolonged unresponsive stupor

02How can you assess the situation at home? Key observations and when to go to an emergency clinic

Observing and documenting key details at home helps the vet quickly understand the clinical course and prioritise diagnostic tests.

Note vomiting frequency, timing, and the appearance of vomit (blood, bile, etc.)
Record stool colour, consistency, frequency, and any presence of blood
Measure and track daily water intake and drinking frequency
Log urination frequency, urine colour, and any episodes of incontinence
Monitor appetite and meal intake, including any episodes of food refusal
Film or note the timing of seizures, lethargy, or unusual behaviour
Compile all observations and bring them to the vet appointment for reference

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

Upon presentation, the vet will use blood tests, biochemistry, urinalysis, and imaging to assess liver function and portosystemic blood flow; advanced tests or pathology may be arranged as needed.

Complete blood count (CBC)

to assess systemic changes such as anaemia or infection

Biochemistry panel

to evaluate liver and kidney function and metabolic abnormalities

Urinalysis

to check for indicators of uraemia or urinary tract infection

Cytology or biopsy

for histopathological evaluation when necessary

Abdominal ultrasound or CT scan

to assess portal blood flow and locate vascular anomalies

Referral to a specialist hospital equipped for advanced imaging and portal haemodynamic assessment is recommended

04What treatment and care are needed after diagnosis? Medications, dietary changes, and home care guide

Treatment may involve surgery or conservative management; the focus of post-operative and long-term follow-up is maintaining clinical stability and monitoring blood and imaging changes.

Some cases require surgical correction of abnormal blood flow to improve clinical signs
Many cases require long-term medication and a specialised diet to manage the condition
Attend regular follow-up visits as advised to monitor blood biochemistry and imaging changes
Monitor home care and report any abnormal behaviour during recovery or ongoing disease management
Discuss with your vet the frequency of monitoring tests and any imaging assessments that may be required
If surgery is needed, seek a specialist veterinary team experienced in portosystemic shunt correction

05What should you prepare before the vet visit? Key information to help the vet quickly identify the cause

Note when symptoms started, how they have changed, and any possible triggers

Bring a video of vomiting or seizure episodes — the clearer, the better for diagnosis

Prepare a record of your pet's diet and water intake for the past week

List all current medications and supplements with their dosages

Compile a list of bowel and urination timing and frequency to bring to the appointment

Contact the clinic in advance to flag the likely tests needed and to plan the appointment schedule

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.