Portosystemic Liver Shunt in Maltese: Symptoms & Management

Portosystemic liver shunts (PSS) are an important, breed-prone condition in Maltese dogs. While many Maltese patients show signs as puppies or young adults, some shunts are diagnosed later in life or present with intermittent signs that become more obvious in senior years (8–9 years old). This article reviews the pathophysiology, clinical signs, diagnostics, and practical management for the senior Maltese, and explains how common comorbidities in this breed — [mitral valve disease](https://seniorpet.org/knowledge/cavalier-king-charles-spaniel-mitral-valve-disease "Mitral Valve Disease Guide") (MVD), luxating patella, cataracts, [dental disease](https://seniorpet.org/knowledge/siamese-cat-dental-disease "Dental Disease in Senior Pets"), collapsed trachea, and white shaker syndrome — affect detection, treatment choice, and long-term care.

Note on the target patient: the guidance below is tailored for Maltese aged roughly 8–9 years (senior for the breed, lifespan ~12–15 years). Management priorities differ from a young dog: comorbidities and anesthetic risk are higher, so invasive therapy decisions must balance life expectancy and [quality of life](https://seniorpet.org/knowledge/siamese-cat-quality-of-life "Quality of Life Assessment").

What is a portosystemic liver shunt (PSS)?

A PSS is an abnormal blood vessel that allows portal blood (from the gastrointestinal tract and spleen) to bypass the liver and enter systemic circulation. The liver’s role in detoxifying nitrogenous wastes and metabolizing many substances is compromised, allowing neurotoxins (notably ammonia) to reach the brain and other organs. In small-breed dogs such as Maltese, congenital extrahepatic shunts are most commonly seen. Acquired shunts can develop secondary to chronic liver disease and portal hypertension.

Pathophysiology essentials:

• Portal blood bypasses hepatocytes → reduced detoxification.
• Accumulation of ammonia and other toxins → hepatic encephalopathy (HE).
• Reduced delivery of nutrients and growth factors → microhepatica and hepatic hypoplasia.
• Urinary changes such as ammonium urate stones from altered hepatic uric acid metabolism.

Why Maltese are at increased risk

Maltese are one of several small/toy breeds predisposed to congenital extrahepatic portosystemic shunts. Breed genetics, small body size, and developmental vascular abnormalities are contributing factors. Clinically, this means owners and veterinarians should keep PSS in mind when Maltese present with neurologic signs, failure to thrive, or intermittent gastrointestinal/urinary signs even in older dogs.

Typical clinical signs in senior Maltese

In seniors, signs may be intermittent, subtle, or overlapped by other age-related conditions.

Neurologic and behavioral

• Disorientation, pacing, staring spells, circling
• Lethargy, depression, reduced learning or house-training regression
• Head pressing, ataxia
• Seizures (partial or generalized); post-ictal behavior changes
• “Mentation waxing and waning” after high-protein meals or stressful events

Gastrointestinal and metabolic

• Intermittent vomiting, diarrhea
• Reduced appetite or periods of polyphagia followed by lethargy
• Weight loss or poor body condition (but some seniors may be obese)

Urinary and dermatologic

• Stranguria or hematuria from urate stones
• Excessive licking, poor coat condition

Important diagnostic clue: episodic neurologic signs that improve after fasting or with lactulose/metronidazole therapy suggest hepatic encephalopathy.

How PSS may be confused with other Maltese senior conditions

• White shaker syndrome (idiopathic tremor syndrome) produces tremors, hyperesthesia, and variable neuro signs, often responsive to corticosteroids. Because steroids can worsen hepatic encephalopathy and liver dysfunction, exclude PSS with liver testing (pre/post-prandial bile acids, serum chemistry) before starting long-term steroids.
• Cognitive decline and cataracts can affect behavior and activity — differentiate with neurologic exam and lab testing.
• Seizures secondary to PSS vs. primary epilepsy: PSS-related seizures often begin earlier in life but can appear later; metabolic workup helps distinguish.

Diagnostic approach: what to test and why

A thorough diagnostics plan is essential for a senior Maltese suspected of PSS. Below is a practical, stepwise approach.

Baseline clinicopathologic testing

- CBC, serum biochemistry (albumin, BUN, ALT, AST, ALP, cholesterol, glucose) - Pre- and post-prandial serum bile acids (sensitive indicator of hepatic functional shunting) - Blood ammonia (lab-dependent; needs careful sample handling) - Urinalysis (look for ammonium urate crystals/stones)

Imaging

- Abdominal ultrasound: can visualize extrahepatic shunts, small liver size, and uroliths; operator-dependent. - CT angiography (CTA): increasingly considered the best noninvasive anatomic test for PSS mapping pre-surgery; high sensitivity for extrahepatic shunts. - Nuclear scintigraphy (99mTc-pertechnetate or MAA): functional test for shunting fraction; useful when CTA is equivocal.

Specialized testing (as indicated)

- Echocardiography and thoracic imaging (if planning surgery) — important because MVD and collapsed trachea increase anesthetic risk. - Bacterial culture if urinary tract infection suspected. - Consultation with a board-certified veterinary surgeon or internist for interpretation and surgical candidacy.

Table: Common tests and expected findings in a Maltese with PSS

| Test | Typical finding in PSS | Notes for senior Maltese | |---|---:|---| | Pre/post-prandial bile acids | Elevated post-prandial, often above lab reference | Highly sensitive; perform before sedation | | Blood ammonia | Increased (variable) | Sample handling is critical; interpret with bile acids | | Serum albumin, BUN | Hypoalbuminemia, low BUN | Reflects decreased hepatic synthetic function | | ALT/ALP | May be normal or mildly altered | Not specific for functional shunting | | Abdominal ultrasound | Microhepatica, visible extrahepatic anomalous vessel | Operator-dependent; fasted abdomen improves visualization | | CT angiography | Anatomical localization of shunt | Preferred for pre-op planning | | Urinalysis | Ammonium urate crystals/stones | Encourage imaging for stone detection |

(Adapted from consensus and veterinary internal medicine resources — see References.)

Medical (non-surgical) management: when and how

In senior Maltese or dogs with significant anesthesia risk (MVD, collapsed trachea, frailty), a medical approach is often chosen. Medical therapy aims to control hepatic encephalopathy, reduce toxin production/absorption, and prevent complications.

Key components:

• Diet: High-quality, highly digestible protein with moderate restriction. Use vet-prescribed hepatic diets (e.g., Royal Canin Hepatic, Hill’s l/d) or formulate with your veterinarian. Avoid abrupt changes; monitor body condition.

- Practical: For a senior Maltese, aim for lower but sufficient protein (exact grams individualized by weight and clinical response) and maintain adequate caloric intake to prevent catabolism.

• Lactulose: osmotic laxative that lowers colonic pH and reduces ammonia absorption.

- Typical starting dose: 0.5–1 mL/kg orally every 8–12 hours, titrated to produce 2–3 soft stools/day.

• Antibiotics: Metronidazole (10–15 mg/kg PO q12h) or ampicillin to suppress ammonia-producing gut bacteria in episodic HE. Some clinicians use rifaximin where available.
• Fluids and correction of metabolic derangements during acute HE episodes.
• Antioxidants and hepatoprotectants: SAMe (S-adenosylmethionine), silymarin (milk thistle), and vitamin E are commonly used adjuncts; evidence varies but they are generally safe and may support hepatic health.
• Seizure control: If seizures occur, use antiepileptic agents that are safe in hepatic dysfunction; levetiracetam (dose adjustments may be needed) is often preferred to phenobarbital (hepatically metabolized and potentially hepatotoxic).

Practical owner guidance:

• Keep lactulose and prescribed antibiotics on hand; start at first signs of disorientation or vomiting and contact your veterinarian.
• Keep a feeding diary to note triggers (high-protein meals, stressors).
• Avoid over-the-counter supplements or herbal remedies without vet approval.

Surgical therapy: definitive options and considerations

Surgical attenuation of the shunt is potentially curative for single congenital extrahepatic shunts. Techniques include gradual occlusion using an ameroid constrictor or cellophane banding, or complete ligation if tolerated. Endovascular coil embolization is an option in selected cases.

Factors in senior Maltese:

• Success rates are generally good for extrahepatic shunts, but older dogs may have smaller, hypoplastic livers that limit recovery.
• Comorbidities (MVD, collapsed trachea, dental disease) increase anesthetic and perioperative risk. A cardiology assessment (echocardiogram) is essential pre-operatively in Maltese with MVD.
• Portal hypertension after rapid shunt occlusion is a life-threatening complication; gradual occlusion methods (ameroid, cellophane) reduce this risk.
• Post-op complications: persistent hepatic dysfunction, seizures, portal hypertension, wound issues.

If considering surgery:

Complete pre-anesthetic workup: blood pressure, thoracic radiographs, echocardiogram, dental clearance if significant oral disease present (dental infections can complicate anesthesia and recovery).

Discuss realistic goals: full resolution vs. improvement, risk profile, and costs.

Plan for post-op hospital monitoring for at least several days and availability of emergency seizure medications.

Research and outcomes: multiple veterinary surgical case series (Veterinary Surgery, Journal of Veterinary Internal Medicine) document improved survival and quality of life after surgical attenuation for extrahepatic shunts, but outcome correlates with age at surgery, liver size/function, and presence of portal hypertension.

How comorbid conditions in senior Maltese affect PSS care

• Mitral Valve Disease (MVD)

- Common in Maltese seniors and increases anesthetic risk. Pre-op echocardiography is required. Medical treatment for MVD (pimobendan, ACE inhibitors, diuretics) must be managed closely around surgery and perioperative fluid therapy.

• Luxating Patella

- Mobility limitations complicate weight control and rehabilitation. Post-op activity restriction for PSS surgery should be coordinated with joint management; physical therapy can be tailored.

• Cataracts / Vision Loss

- Vision impairment may worsen after HE episodes. Make home environment safe and consistent to reduce stress and confusion that can trigger HE episodes.

• Dental Disease

- Poor dental health can seed bacteremia and worsen systemic inflammation. Prioritize dental cleaning and extractions under anesthesia only after assessing cardiac and anesthetic risks; consider staged procedures or local treatments if full anesthesia is not safe.

• Collapsed Trachea

- Increases risk with general anesthesia and places limits on sedation choices. Discuss airway management strategies with the anesthesia team; pre-op cough control may be necessary.

• White Shaker Syndrome

- Tremor disorders may be treated with corticosteroids, which can worsen liver disease and HE. Rule out PSS and other metabolic causes before initiating steroids. If tremor syndrome co-exists with PSS, discuss steroid risks and alternatives (immunomodulatory therapy under specialist guidance).

Practical owner-centered care plan for a senior Maltese with suspected or confirmed PSS

Immediate steps at home

- Keep a detailed symptom log (episodes of disorientation, timing relative to meals, vomiting, seizures). - Do not start steroids for tremors without vet testing (bile acids, chemistry) to exclude PSS. - Maintain hydration, routine feeding schedule, and avoid high-protein treats (e.g., table scraps, large amounts of liver).

Veterinary visit checklist

- Request pre- and post-prandial bile acids and routine chemistry. - Ask about abdominal ultrasound vs. CT angiography; CTA provides best anatomic mapping if surgery is a possibility. - If your Maltese has a heart murmur or cough, ask for echocardiography and thoracic radiographs before anesthesia.

Nutrition and medications

- Transition to a vet-recommended hepatic or prescription diet slowly over 3–7 days. - Use lactulose and antibiotics as prescribed; keep dosing schedule tight. - Avoid NSAIDs or other drugs without vet approval; discuss safe pain control if luxating patella or dental pain is present.

Preparing for potential surgery

- Pre-anesthetic optimization: treat dental infections, manage [heart disease](https://seniorpet.org/knowledge/cavalier-king-charles-spaniel-mitral-valve-disease "Heart Disease in Senior Pets"), control respiratory issues. - Post-op plan: arrange for in-hospital monitoring, IV fluids, seizure medications, and a quiet recovery area at home.

Long-term monitoring

- Recheck bloodwork and bile acids 4–6 weeks after any therapeutic change, then every 3–6 months. - Monitor weight, appetite, stool quality, and behavior. - Annual dental checks and cleaning when safe.

Emergency signs — when to seek immediate veterinary care

• Seizure activity lasting >5 minutes or cluster seizures
• Prolonged stupor or coma
• Severe, uncontrolled vomiting or diarrhea causing dehydration
• Sudden collapse or severe respiratory distress

Call your veterinarian or local emergency clinic immediately if these occur.

Prognosis

Prognosis varies:

• Surgical attenuation in suitable candidates often yields good long-term survival and quality of life improvements; some dogs may need lifelong medical support.
• Medically managed senior Maltese can maintain good quality of life for months to years with diligent dietary control and prompt management of HE episodes, but are at risk for recurrent episodes and urinary stones.
• Comorbidities (MVD, collapsed trachea, severe hepatic hypoplasia) reduce surgical candidacy and can worsen prognosis.

Practical case examples

• Case A (surgical candidate): 8-year-old Maltese with episodic HE, elevated bile acids, CTA confirming single extrahepatic shunt, normal echocardiogram. Undergoes ameroid constrictor placement, monitored for portal hypertension, placed on lactulose and hepatic diet initially, weaned later. Long-term: markedly improved behavior and appetite; 1–2 follow-up bile acid checks annually.
• Case B (medical management): 9-year-old Maltese with PSS on ultrasound but severe MVD and collapsed trachea; owner and vet opt for medical therapy (hepatic diet + lactulose + metronidazole), close monitoring, and dental care under local anesthesia as needed. Owner maintains a symptom log and keeps lactulose for episodic management.

Communication and decision-making with your veterinarian

• Ask for explanations of the specific shunt type and how it affects therapy choices.
• Discuss quality-of-life goals, not just test results — for seniors, the goal may be symptom control rather than curative surgery.
• If surgery is recommended, request a consult with a boarded surgeon experienced in PSS and discuss perioperative cardiac and respiratory risk mitigation.
• Keep a copy of all imaging and lab reports; second opinions are reasonable for complex decisions.

References and further reading

• Nelson RW, Couto CG. Small Animal Internal Medicine. (Textbook overview on hepatic disorders and PSS.)
• King LG, et al. Management of portosystemic shunts in dogs: surgical and medical options. Journal of Veterinary Internal Medicine. (Review articles on outcomes and surgical techniques.)
• Veterinary Surgery and radiology literature on CT angiography for shunt localization and outcomes of ameroid constrictor vs. cellophane banding.
• Clinical practice guidelines for hepatic encephalopathy and small companion animals (various vet specialty sources).

(Ask your primary veterinarian for copies of cited studies or a referral to a veterinary internal medicine or surgery specialist for the most current, peer-reviewed literature relevant to your Maltese.)

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Caring for a senior Maltese with a portosystemic liver shunt requires breed-aware vigilance, careful diagnostics, and realistic, individualized therapy plans that account for the high prevalence of cardiac, respiratory, and orthopedic comorbidities in this breed. With early recognition, appropriate testing, and coordinated care between your primary veterinarian and specialists, many Maltese can enjoy meaningful quality of life whether treated medically or surgically.