# Maltese Health Problems: White Shaker Syndrome and Portosystemic Shunt


## Key Takeaways

-   **White Shaker Syndrome (WSS)** is an immune-mediated inflammatory condition of the cerebellum (cerebellitis) in young adult Maltese (1-2 years), characterized by generalized, fine, rhythmic tremors that worsen with purposeful movement (intention tremors) and are often triggered by excitement or stress. Diagnosis relies on clinical signs, neurological examination, exclusion of other causes, and a positive response to corticosteroid therapy.
-   **Portosystemic Shunt (PSS)** is a congenital abnormality where abnormal blood vessels bypass the liver, leading to toxin accumulation and hepatic encephalopathy, typically presenting in young Maltese (<1 year) with stunted growth, poor appetite, excessive drooling, and neurological signs like head pressing or disorientation, often post-prandially.
-   **Diagnostic differentiation** is critical: WSS is primarily neurological with tremors as the hallmark, while PSS is hepatic/cardiovascular with systemic signs including neurological deficits and urinary stones; diagnostic tools include neurological exams and steroid trials for WSS, versus bile acid tests and CT angiography for PSS.
-   **Treatment strategies diverge significantly**: WSS is managed with immunosuppressive corticosteroids (e.g., prednisone), often long-term, to reduce brain inflammation, while PSS requires either surgical correction of the abnormal vessel or lifelong medical management involving low-protein diets, lactulose, and antibiotics to mitigate toxin effects.
-   **Early recognition and veterinary intervention** are paramount for both conditions; sudden severe tremors warrant immediate assessment for WSS, while neurological signs post-eating, excessive drooling, or stunted growth in a young Maltese are red flags for PSS, with prompt diagnosis significantly improving prognosis for both.

---

If you own a Maltese, you have likely chosen a companion known for its silky white coat and gentle demeanor. However, this beloved breed carries a genetic predisposition to specific, serious health conditions. Two of the most concerning are **White Shaker Syndrome** (also called generalized tremor syndrome) and **Portosystemic Shunt** (a liver abnormality). This article provides a definitive, source-grounded guide to understanding, identifying, and managing these conditions.

**Owner Triage Summary:** If your Maltese suddenly develops full-body tremors, especially when excited or moving, or if they show signs of stunted growth, excessive drooling, or neurological oddities after eating, do not wait. These are red flags for White Shaker Syndrome or a liver shunt. Both require prompt veterinary intervention. White Shaker Syndrome is often manageable with corticosteroids, while a portosystemic shunt may require surgical correction or lifelong medical management. Early diagnosis significantly improves the prognosis for both.

## At a Glance: Comparing the Two Conditions

This table provides a quick clinical comparison to help you understand the fundamental differences between these two distinct Maltese health problems.

| Feature | White Shaker Syndrome (WSS) | Portosystemic Shunt (PSS) |
| :--- | :--- | :--- |
| **Primary System** | Neurological | Hepatic (Liver) and Cardiovascular |
| **Core Problem** | Inflammation of the brain (cerebellitis) causing tremors | Abnormal blood vessel bypasses the liver, allowing toxins to reach the brain |
| **Typical Age of Onset** | Young adults (1-2 years) | Young dogs, often under 1 year |
| **Classic Signs** | Generalized, fine tremors; intention tremors (worse when moving); nystagmus (abnormal eye movements) | Stunted growth, poor appetite, excessive drooling, head pressing, behavioral changes, urinary stones |
| **Hallmark Trigger** | Excitement, stress, or purposeful movement | Eating a high-protein meal (post-prandial) |
| **Diagnosis** | Neurological exam, ruling out other causes; trial therapy with steroids | Blood tests (bile acids), ultrasound, CT scan |
| **Treatment** | Corticosteroids (e.g., prednisone), often long-term | Surgical correction (ameroid constrictor) or medical management (low-protein diet, lactulose, antibiotics) |
| **Prognosis** | Good to excellent with treatment; many dogs can taper off medication | Good with surgery; guarded with medical management alone |

## Understanding White Shaker Syndrome in Maltese Dogs

White Shaker Syndrome (WSS), also known as generalized tremor syndrome (GTS), is a neurological condition that primarily affects small, white-coated breeds, with the Maltese being a classic example. The condition is characterized by sudden, generalized, and involuntary muscle tremors.

### What is White Shaker Syndrome?

WSS is an inflammatory condition of the central nervous system, specifically affecting the cerebellum, the part of the brain responsible for coordination and fine motor control. The exact cause is unknown, but it is widely believed to be an immune-mediated disorder. The body's own immune system mistakenly attacks the brain tissue, leading to inflammation (cerebellitis). This inflammation disrupts normal neurological signaling, resulting in the characteristic tremors.

While the name suggests it only affects white dogs, it can occur in other colors and breeds, but the Maltese, Bichon Frise, and West Highland White Terrier are overrepresented.

### Clinical Signs and Symptoms

The hallmark sign of WSS is a fine, rapid, and rhythmic tremor that affects the entire body. These tremors can vary in intensity.

- **Intention Tremors:** These tremors worsen when the [dog](/knowledge/veterinary-medicine/clinical-methods/dog) is trying to perform a purposeful action, such as reaching for a food bowl or picking up a toy. This is a key diagnostic feature.
- **Tremors at Rest:** Tremors often diminish or disappear entirely when the dog is completely relaxed or sleeping.
- **Exacerbating Factors:** Excitement, stress, or anticipation (like seeing a leash) can significantly worsen the tremors.
- **Other Neurological Signs:** Some dogs may also exhibit nystagmus (rapid, involuntary eye movements), head tilt, or a slightly uncoordinated gait (ataxia).
- **Normal Behavior:** Importantly, affected dogs typically remain bright, alert, and responsive. They do not usually have seizures or changes in mentation.

### How Veterinarians Diagnose White Shaker Syndrome

There is no single definitive test for WSS. Diagnosis is typically based on:

1.  **Signalment and History:** A young adult Maltese presenting with the classic clinical signs.
2.  **Neurological Examination:** A thorough exam to rule out other neurological deficits and confirm the tremors are the primary issue.
3.  **Ruling Out Other Causes:** The veterinarian will need to rule out other potential causes of tremors, including:
    - Toxin exposure (e.g., chocolate, certain insecticides)
    - Metabolic diseases (e.g., hypoglycemia, which can be seen in toy breeds)
    - Electrolyte imbalances (e.g., hypocalcemia)
    - Other inflammatory brain diseases (e.g., granulomatous meningoencephalomyelitis)
4.  **Trial Therapy:** A positive response to corticosteroid treatment (e.g., prednisone) is a strong indicator of WSS, as the condition is immune-mediated.

### Evidence-Based Management and Treatment

The cornerstone of WSS treatment is immunosuppression.

- **Corticosteroids:** Prednisone is the most commonly prescribed medication. The initial dose is typically high, then gradually tapered down over several months. Most dogs show a dramatic improvement within days to a week of starting treatment.
- **Long-Term Management:** Many dogs require long-term, sometimes lifelong, low-dose corticosteroid therapy to keep tremors at bay. Some dogs may eventually be weaned off medication completely, but relapses can occur.
- **Alternative Medications:** In cases where corticosteroids are not effective or cause significant side effects, other immunosuppressive drugs like azathioprine or levetiracetam may be considered by a veterinary neurologist.

**Prognosis:** The prognosis for WSS is generally excellent. With appropriate treatment, the vast majority of dogs experience significant improvement or complete resolution of tremors. The condition is not painful, and affected dogs can enjoy a good quality of life.

## Understanding Portosystemic Shunt in Maltese Dogs

Portosystemic shunt (PSS), also known as a liver shunt, is a congenital condition where the blood supply from the intestines bypasses the liver. This is a serious Maltese health problem that affects the body's ability to process toxins and nutrients.

### What is a Portosystemic Shunt?

In a normal dog, blood from the gastrointestinal tract is rich in nutrients, bacteria, and toxins absorbed from the intestines. This blood is routed to the liver via the portal vein. The liver's job is to filter these substances, detoxify harmful compounds like ammonia, and process nutrients.

In a dog with a PSS, an abnormal blood vessel connects the portal vein directly to the systemic circulation, bypassing the liver entirely. This means that toxins, especially ammonia, are not filtered and circulate throughout the body. When these toxins reach the brain, they cause a condition called hepatic encephalopathy (HE), leading to neurological signs.

### Clinical Signs and Symptoms

The signs of a PSS are often vague and can be mistaken for other conditions. They are frequently seen in puppies and young dogs.

- **Gastrointestinal Signs:** Poor growth or failure to thrive, poor appetite, vomiting, and diarrhea (or diarrhoea).
- **Neurological Signs (Hepatic Encephalopathy):** These are often the most dramatic signs and can be triggered by eating a high-protein meal. Signs include:
    - Lethargy and depression
    - Head pressing
    - Circling
    - Disorientation
    - Behavioral changes (e.g., staring into space, unresponsiveness)
    - Seizures
    - Excessive drooling (ptyalism)
- **Urinary Signs:** Dogs with PSS are prone to developing urate bladder stones, which can cause straining to urinate and blood in the urine.
- **Other Signs:** A classic but not always present sign is a copper-colored or bronze appearance to the urine.

### How Veterinarians Diagnose Portosystemic Shunt

Diagnosis requires a combination of blood tests and imaging.

1.  **Baseline Bloodwork:** A complete blood count (CBC) and biochemistry profile may show:
    - Low blood urea nitrogen (BUN)
    - Low albumin (hypoalbuminemia)
    - Low blood glucose (hypoglycemia)
    - Elevated liver enzymes (ALT, ALP)
    - Microcytosis (small red blood cells)
2.  **Bile Acid Test:** This is the most specific and sensitive blood test for a liver shunt. It involves taking a blood sample after a 12-hour fast, then feeding a meal and taking another sample two hours later. Dogs with a shunt will have significantly elevated bile acid levels in both samples.
3.  **Diagnostic Imaging:**
    - **Ultrasound:** An experienced veterinary radiologist can often visualize the abnormal vessel using ultrasound.
    - **CT Angiography:** This is the gold standard for diagnosing a PSS. It provides a detailed 3D image of the liver's blood vessels, confirming the presence, location, and type of shunt. This is crucial for surgical planning.

### Evidence-Based Management and Treatment

Treatment for a PSS can be medical or surgical.

- **Medical Management:** This is a lifelong approach aimed at minimizing the clinical signs of HE. It is often used to stabilize a dog before surgery or as the primary treatment if surgery is not an option.
    - **Diet:** A highly digestible, low-protein diet is essential to reduce the amount of ammonia produced in the gut.
    - **Lactulose:** This is a synthetic sugar that is not absorbed. It works by acidifying the colon, which traps ammonia and promotes its excretion in the feces.
    - **Antibiotics:** Antibiotics like neomycin or metronidazole are used to reduce the population of ammonia-producing bacteria in the colon.
- **Surgical Correction:** The definitive treatment for a single, extrahepatic shunt (the most common type in Maltese dogs) is surgery. The goal is to gradually occlude (close off) the abnormal vessel, forcing blood to flow through the liver. This is most commonly done using an ameroid constrictor, a device that slowly closes the vessel over several weeks, allowing the liver to adapt and regenerate.

**Prognosis:** The prognosis for dogs with a single, surgically correctable shunt is good to excellent, with many dogs living normal, healthy lives after recovery. The prognosis for dogs managed medically is more guarded, as they require strict lifelong management and are at risk for recurring neurological episodes.

## Emergency Red Flags for Maltese Owners

Certain signs in your Maltese require immediate veterinary attention. Do not wait to see if they improve.

- **For White Shaker Syndrome:** Sudden onset of severe, whole-body tremors that prevent the dog from standing or walking.
- **For Portosystemic Shunt:** Any neurological sign, especially after eating, including head pressing, circling, disorientation, seizures, or profound lethargy. Excessive drooling in a young Maltese is also a significant red flag.

If you observe any of these signs, contact your veterinarian or an emergency veterinary clinic immediately.

## Prevention and Breed-Specific Considerations

Neither White Shaker Syndrome nor Portosystemic Shunt can be prevented through diet, exercise, or environmental changes, as they are congenital or immune-mediated conditions.

- **Genetic Screening:** The most effective way to reduce the incidence of these conditions is for breeders to screen their breeding stock. While there is no genetic test for WSS, responsible breeders should not breed dogs that have exhibited the condition. For PSS, breeders should have their breeding dogs screened with bile acid tests or imaging to ensure they are not carriers.
- **Early Recognition:** The best thing an owner can do is be aware of the early signs and seek veterinary care promptly. Early diagnosis and treatment are the most critical factors in achieving a positive outcome.

## Limitations and When to Contact a Veterinarian

This article provides a comprehensive overview of two significant Maltese health problems. However, it is crucial to understand its limitations. Breed-level information cannot predict what any individual dog will experience. The clinical presentation of these diseases can vary significantly, and other conditions can mimic their signs.

This information is educational and is not a substitute for veterinary diagnosis or treatment. Only a licensed veterinarian can perform the necessary examinations and tests to accurately diagnose your pet. If you have any concerns about your Maltese's health, or if you observe any of the signs discussed in this article, you should contact your veterinarian without delay. They can provide a tailored diagnostic and treatment plan specific to your dog's needs.

## The Clinical Reality of White Shaker Syndrome: Beyond the Tremors

Understanding White Shaker Syndrome requires moving beyond the surface-level observation of a shaking dog. The condition, while visually alarming, represents a specific inflammatory process within the central nervous system. For Maltese owners, recognizing the nuances of this condition can make the difference between a delayed diagnosis and a rapid, effective treatment plan.

### The Inflammatory Mechanism and Why It Matters

The term "White Shaker Syndrome" is somewhat of a misnomer, as the condition is not exclusive to white dogs, nor is it a simple tremor disorder. The underlying pathology is a diffuse, mild inflammation of the brain, particularly affecting the cerebellum and its connections. This condition is formally classified as an idiopathic cerebellitis, meaning the inflammation has no identifiable infectious cause. The immune-mediated theory suggests that something triggers the dog's own immune system to target neural tissue, resulting in the release of inflammatory cytokines that disrupt normal motor signaling.

This understanding is crucial for owners because it explains why the condition responds so dramatically to immunosuppressive therapy. When a veterinarian prescribes corticosteroids, they are not simply sedating the dog or masking the tremor. They are directly addressing the inflammatory cascade that is causing the neurological dysfunction. The rapid response to treatment is not just a clinical convenience; it is a diagnostic clue that supports the immune-mediated hypothesis.

### The Spectrum of Tremor Presentation

Not all tremors in a Maltese are created equal, and the specific characteristics of the tremor can help differentiate WSS from other conditions. The classic WSS tremor is described as a fine, rapid, rhythmic oscillation that involves the entire body. However, the severity can range from a barely perceptible quiver to a disabling shake that interferes with ambulation.

- **Action Tremors:** These occur during voluntary movement. A dog with WSS may be relatively still when lying down but begin to tremble when asked to walk or when reaching for a treat.
- **Postural Tremors:** These occur when the dog is maintaining a specific posture, such as standing or holding its head up.
- **Intention Tremors:** These are the most characteristic and are often most pronounced when the dog is attempting a goal-directed movement, such as placing a paw on a toy or eating from a bowl. The tremor amplitude often increases as the dog gets closer to the target.

The fact that tremors typically cease during sleep is a valuable diagnostic feature. True seizure activity or other neurological conditions often manifest differently during rest. Owners who can provide a clear description of when the tremors occur, what makes them worse, and what makes them better will significantly aid the veterinarian in the diagnostic process.

### The Role of Stress and Excitement in Triggering Episodes

One of the most challenging aspects of WSS for owners is the unpredictable nature of tremor flare-ups. While the underlying inflammation is constant, the visible manifestation of the condition is often triggered by external factors. Excitement, such as the arrival of a visitor or the anticipation of a walk, can cause a dramatic increase in tremor intensity. Stress, including loud noises, changes in routine, or travel, can similarly exacerbate the condition.

This does not mean that owners should keep their Maltese in a constant state of calm sedation. Rather, it highlights the importance of understanding that the condition is dynamic. A dog that is well-managed on medication may still experience transient increases in tremor activity during high-arousal situations. This is not necessarily a sign of treatment failure, but rather a reflection of the underlying neurological sensitivity. Owners should document these episodes and discuss them with their veterinarian, as they may inform adjustments to medication timing or dosage.

### Differentiating WSS from Seizure Activity

A common concern among owners is whether the tremors of WSS are actually seizures. This distinction is critical, as the treatment approaches are fundamentally different. Seizures are characterized by abnormal, excessive electrical activity in the brain, often resulting in loss of consciousness, uncontrolled muscle contractions, and autonomic signs such as salivation or urination. WSS tremors, in contrast, do not involve a loss of consciousness. The dog remains fully aware and responsive throughout the episode.

Another key difference is the pattern of the event. Seizures typically have a distinct onset, duration, and post-ictal phase (a period of confusion or lethargy following the event). WSS tremors are more continuous and are not followed by a recovery period. A dog with WSS can typically be distracted from its tremors, whereas a dog having a seizure cannot. If an owner is uncertain whether their dog is experiencing tremors or seizures, a video recording of the event can be invaluable for the veterinarian to review.

## The Diagnostic Journey for White Shaker Syndrome

The path to a WSS diagnosis is often one of exclusion. Because there is no single blood test or imaging study that can definitively confirm the condition, veterinarians rely on a combination of clinical findings, diagnostic testing, and response to therapy.

### The Importance of a Thorough Neurological Examination

A board-certified veterinary neurologist or an experienced general practitioner will perform a comprehensive neurological examination. This goes beyond simply observing the tremor. The veterinarian will assess cranial nerve function, postural reactions, spinal reflexes, and gait. The goal is to determine whether the tremors are the only neurological abnormality or whether there are other deficits that point to a different or more widespread disease process.

In a classic case of WSS, the neurological examination is otherwise normal. The dog is bright, alert, and responsive. There are no signs of weakness, proprioceptive deficits (knuckling), or cranial nerve abnormalities. This "clean" neurological exam, in the face of generalized tremors, is a strong indicator of WSS.

### Ruling Out Metabolic and Toxic Causes

Before settling on a diagnosis of WSS, the veterinarian must rule out other conditions that can cause tremors. This is where baseline bloodwork becomes essential.

- **Hypoglycemia:** Toy breeds like the Maltese are prone to low blood sugar, especially as puppies. Hypoglycemia can cause weakness, tremors, and even collapse. A simple blood glucose measurement can quickly rule this out.
- **Hypocalcemia:** Low blood calcium levels can cause muscle tremors and fasciculations. This is less common than hypoglycemia but is easily identified on a biochemistry panel.
- **Toxin Exposure:** Certain toxins, including chocolate, caffeine, and some insecticides, can cause tremors. A thorough history of the dog's environment and access to potential toxins is crucial.
- **Electrolyte Imbalances:** Abnormalities in sodium, potassium, or magnesium can also lead to neuromuscular irritability and tremors.

The diagnostic workup for a suspected WSS case is therefore not just about confirming the condition, but about systematically excluding these other, potentially more dangerous, causes.

### The Role of Advanced Imaging

In many cases, a diagnosis of WSS is made based on signalment, history, clinical signs, and a positive response to corticosteroid therapy. However, if the dog does not respond as expected, or if the neurological examination reveals additional deficits, advanced imaging may be recommended.

Magnetic resonance imaging (MRI) of the brain is the most sensitive imaging modality for evaluating inflammatory brain disease. In some cases of WSS, an MRI may show subtle changes in the cerebellum, such as increased signal intensity on certain imaging sequences. However, it is important to note that many dogs with WSS have a completely normal MRI. The absence of MRI changes does not rule out the condition, and the presence of changes is not specific to WSS. Cerebrospinal fluid (CSF) analysis may also be performed, which can show a mild increase in white blood cell count, supporting the inflammatory nature of the condition.

### The Diagnostic Value of a Therapeutic Trial

The decision to initiate a trial of corticosteroids is often a collaborative one between the veterinarian and the owner. If the clinical picture is highly suggestive of WSS, and other causes have been ruled out, a trial of prednisone is a reasonable next step. The response to this trial is often dramatic. Owners frequently report a significant reduction in tremors within 48 to 72 hours of starting treatment. This rapid response is not only reassuring for the owner but also serves as a strong piece of evidence supporting the diagnosis.

It is important for owners to understand that a therapeutic trial is not a "wait and see" approach. It is a deliberate diagnostic maneuver that provides valuable information. If the dog does not respond to corticosteroids, the veterinarian will need to reconsider the diagnosis and pursue additional testing.

## The Long-Term Management of White Shaker Syndrome

Managing a Maltese with WSS is a long-term commitment that requires patience, observation, and a strong partnership with the veterinary team. The goal of treatment is not just to eliminate tremors, but to maintain the dog's quality of life while minimizing the side effects of long-term medication.

### The Art of Corticosteroid Tapering

The initial dose of prednisone for WSS is typically high enough to quickly suppress the inflammatory response. Once the tremors are controlled, the dose is gradually tapered over a period of weeks to months. The goal is to find the lowest effective dose that keeps the dog symptom-free. This tapering process must be done slowly and under the guidance of a veterinarian. Abruptly stopping corticosteroids can lead to a severe relapse of tremors and can also cause a dangerous condition called Addisonian crisis, where the body is unable to produce its own cortisol.

The tapering schedule is not a one-size-fits-all protocol. Some dogs can be weaned off medication entirely, while others require a low maintenance dose for life. The veterinarian will guide the owner through this process, adjusting the schedule based on the dog's response. Owners should be prepared for the possibility of a relapse during the tapering process, which may necessitate a temporary increase in the dose before resuming a slower taper.

### Monitoring for Corticosteroid Side Effects

Long-term corticosteroid use is not without its challenges. Owners must be vigilant for potential side effects, which can include:

- **Increased Thirst and Urination:** This is one of the most common and noticeable side effects. The dog may need more frequent bathroom breaks and may drink more water than usual.
- **Increased Appetite:** Corticosteroids can stimulate appetite, which can lead to weight gain. Owners should monitor their dog's weight and adjust food portions accordingly.
- **Panting:** Increased panting is a common side effect, even when the dog is not hot or exercised.
- **Weakened Immune System:** Corticosteroids suppress the immune system, making the dog more susceptible to infections. Owners should be vigilant for signs of illness, such as coughing, sneezing, or skin infections.
- **Gastrointestinal Upset:** Corticosteroids can cause stomach irritation and increase the risk of ulcers. Administering the medication with food can help mitigate this.

These side effects are often dose-dependent and may become less pronounced as the dose is tapered. However, they are an important consideration in the long-term management of the condition. The veterinarian may recommend regular bloodwork to monitor liver enzymes and other parameters while the dog is on long-term steroid therapy.

### The Role of Adjunctive Therapies

In cases where corticosteroids are not fully effective or cause unacceptable side effects, a veterinary neurologist may recommend additional immunosuppressive or symptomatic medications. Drugs such as azathioprine or levetiracetam may be used in combination with a lower dose of prednisone. These medications work through different mechanisms and can allow for a reduction in the corticosteroid dose, thereby minimizing its side effects. This approach, known as a "steroid-sparing" strategy, is becoming increasingly common in the management of immune-mediated neurological conditions.

### The Importance of Routine and Predictability

While medication is the cornerstone of WSS treatment, environmental management can also play a role. Maintaining a consistent daily routine can help reduce stress and anxiety, which are known triggers for tremor flare-ups. This includes consistent feeding times, walk times, and sleep schedules. Creating a calm and predictable home environment can help minimize the frequency and severity of tremor episodes.

## Portosystemic Shunt: A Deeper Dive into Pathophysiology

Portosystemic shunt is a condition that fundamentally alters the way a dog's body processes nutrients and waste products. To truly understand the impact of this condition, it is helpful to understand the normal physiology of the liver and how a shunt disrupts this delicate balance.

### The Liver as the Body's Chemical Factory

The liver is a remarkable organ with over 500 functions. Among its most critical roles are detoxification, protein synthesis, and nutrient processing. Blood from the gastrointestinal tract is uniquely positioned to be processed by the liver first. This blood, carried by the portal vein, is rich in nutrients absorbed from food, as well as byproducts of digestion, including ammonia, which is produced when proteins are broken down by bacteria in the gut.

In a healthy dog, this nutrient-rich and toxin-laden blood is delivered directly to the liver. The liver cells, or hepatocytes, extract what is needed for energy and metabolism, and they convert toxic ammonia into urea, which is then excreted by the kidneys. This process ensures that the systemic circulation, which delivers blood to the brain and other organs, is free of these harmful substances.

### The Shunt: A Bypass with Devastating Consequences

A portosystemic shunt is an abnormal vascular connection that allows blood from the portal vein to bypass the liver and enter the systemic circulation directly. This means that the liver is effectively "starved" of the nutrients it needs to grow and function properly, and the body is flooded with toxins that it cannot process.

The most immediate and dramatic consequence of this bypass is hepatic encephalopathy. The brain is highly sensitive to toxins, particularly ammonia. When ammonia and other neurotoxins reach the brain, they disrupt neurotransmitter function, leading to a range of neurological signs. The severity of these signs can vary from subtle behavioral changes to life-threatening seizures.

### The Two Main Types of Shunts

Portosystemic shunts are classified based on their origin and location.

- **Congenital Shunts:** These are present at birth and are the most common type in Maltese dogs. They are typically a single, abnormal vessel. The most common congenital shunt in small breeds is an extrahepatic shunt, meaning it is located outside the liver. These are often amenable to surgical correction.
- **Acquired Shunts:** These develop later in life as a result of chronic liver disease, such as cirrhosis. They are typically multiple, small vessels that form as the body attempts to bypass a failing liver. These are much more difficult to treat and are not typically the type seen in young Maltese dogs with congenital disease.

### The Unique Susceptibility of the Maltese Breed

The Maltese breed is overrepresented for congenital portosystemic shunts. While the exact genetic basis is not fully understood, it is believed to be an inherited trait. This is why responsible breeding practices are so critical. Breeders who screen their breeding stock for this condition can significantly reduce the incidence of PSS in future generations.

### The Clinical Presentation: A Constellation of Signs

The signs of a portosystemic shunt are often vague and can be easily missed by owners and even some veterinarians. The condition is a great imitator, and its signs can mimic other, more common conditions.

- **Failure to Thrive:** A puppy with a shunt may be smaller than its littermates, have a poor appetite, and fail to gain weight at a normal rate. This is due to the liver's inability to process nutrients properly.
- **Intermittent Gastrointestinal Signs:** Vomiting and diarrhea can occur, but they are often intermittent and may not be severe enough to prompt a veterinary visit.
- **Behavioral and Neurological Signs:** These are the most concerning and are often the reason owners finally seek help. Signs can include:
    - Lethargy and depression
    - Staring blankly into space
    - Circling or pacing
    - Head pressing against walls or furniture
    - Disorientation and confusion
    - Unresponsiveness to commands
    - Seizures
- **Excessive Drooling (Ptyalism):** This is a classic sign of hepatic encephalopathy in cats, but it can also be seen in dogs with PSS. The drooling is often triggered by eating.
- **Urinary Issues:** Dogs with PSS are prone to developing urate bladder stones. These stones can cause straining to urinate, blood in the urine, and frequent attempts to urinate. In male dogs, a urate stone can become lodged in the urethra, causing a life-threatening urinary obstruction.

### The Post-Prandial Trigger

One of the most distinctive features of hepatic encephalopathy is its relationship to eating. A high-protein meal can trigger a sudden onset of neurological signs. This is because the digestion of protein produces a large amount of ammonia in the gut, which is then absorbed into the bloodstream and, due to the shunt, bypasses the liver and goes directly to the brain. Owners may notice that their dog is normal in the morning but becomes lethargic, disoriented, or begins to drool excessively within an hour or two of eating.

## The Diagnostic Workup for Portosystemic Shunt

Diagnosing a portosystemic shunt requires a systematic approach that combines bloodwork, bile acid testing, and advanced imaging. Each step provides a piece of the puzzle, and together they paint a complete picture of the dog's condition.

### The Value and Limitations of Baseline Bloodwork

A routine blood panel can provide the first clues that a shunt is present. However, the changes are often subtle and can be present in other liver diseases.

- **Low Blood Urea Nitrogen (BUN):** Because the liver is not processing ammonia into urea, BUN levels are often low.
- **Low Albumin:** The liver is responsible for producing albumin, a major blood protein. A shunting liver may not produce enough, leading to hypoalbuminemia.
- **Low Blood Glucose:** The liver also plays a role in glucose regulation. A shunting liver may not be able to maintain adequate blood sugar levels, leading to hypoglycemia.
- **Microcytosis:** This refers to red blood cells that are smaller than normal. It is a common finding in dogs with PSS, although the exact mechanism is not fully understood.
- **Elevated Liver Enzymes:** ALT and ALP may be mildly elevated, but they are often not as high as in other liver diseases like hepatitis.

These findings are suggestive but not diagnostic. A dog with a shunt can have a completely normal blood panel, and a dog with a different liver disease can have similar changes.

### The Bile Acid Test: A Functional Assessment

The bile acid test is the most valuable blood test for diagnosing a portosystemic shunt. Bile acids are produced by the liver and are essential for fat digestion. In a healthy dog, bile acids are efficiently extracted from the blood by the liver and recycled. In a dog with a shunt, a significant portion of bile acids bypass the liver and remain in the systemic circulation.

The test is performed in two steps. First, a blood sample is taken after a 12-hour fast. The dog is then fed a meal, and a second blood sample is taken two hours later. In a dog with a shunt, both the fasting and post-prandial bile acid levels will be significantly elevated. This test is highly sensitive and specific for PSS, making it an excellent screening tool.

### The Role of Abdominal Ultrasound

Ultrasound is a non-invasive imaging modality that can be used to evaluate the liver and its blood vessels. An experienced veterinary radiologist can often identify the abnormal shunt vessel on ultrasound. The liver itself may also appear smaller than normal, which is a common finding in dogs with congenital shunts.

However, ultrasound is operator-dependent, and the results can be influenced by the dog's size, body condition, and the presence of gas in the intestines. A negative ultrasound does not completely rule out a shunt, and a positive finding should be confirmed with a more definitive imaging study.

### CT Angiography: The Gold Standard

Computed tomography (CT) angiography is the gold standard for diagnosing a portosystemic shunt. This advanced imaging technique involves injecting a contrast dye into the bloodstream and then taking a series of CT images. The dye highlights the blood vessels, allowing the radiologist to create a detailed 3D reconstruction of the liver's vascular anatomy.

This imaging study provides crucial information for surgical planning. It can confirm the presence of a shunt, determine its exact location, and identify whether it is a single vessel or a more complex anomaly. This information is essential for the surgeon to choose the most appropriate surgical approach.

## Treatment Strategies for Portosystemic Shunt

The treatment of a portosystemic shunt is a two-pronged approach. Medical management is used to stabilize the dog and control clinical signs, while surgical correction offers the potential for a definitive cure.

### Medical Management: Stabilization and Long-Term Care

Medical management is not a cure, but it is a critical component of treatment. It is used to stabilize a dog before surgery and is the primary treatment for dogs that are not surgical candidates.

- **Dietary Modification:** The cornerstone of medical management is a highly digestible, low-protein diet. This reduces the amount of ammonia produced in the gut. The diet should also be low in purines, which are precursors to uric acid and urate stones. Commercial prescription diets are available that are specifically formulated for dogs with liver disease.
- **Lactulose:** This synthetic sugar is not absorbed by the intestines. It works by acidifying the colon, which traps ammonia in the gut and promotes its excretion in the feces. It also has a laxative effect, which helps to reduce the time bacteria have to produce ammonia.
- **Antibiotics:** Antibiotics such as neomycin or metronidazole are used to reduce the population of ammonia-producing bacteria in the colon. This is an important adjunct to dietary therapy.

Medical management requires strict owner compliance. The dog must be fed the prescribed diet and receive all medications on a consistent schedule. Any deviation can trigger a flare-up of hepatic encephalopathy.

### Surgical Correction: The Path to a Cure

Surgery is the definitive treatment for a single, congenital, extrahepatic shunt. The goal of surgery is to gradually occlude the abnormal vessel, forcing blood to flow through the liver. This allows the liver to regenerate and develop a normal portal blood supply.

The most common surgical technique involves placing an ameroid constrictor around the shunt vessel. This device is a ring made of a hygroscopic material that slowly swells over several weeks, gradually closing off the vessel. This gradual closure is important because it allows the liver to adapt to the increased blood flow without causing a dangerous condition called portal hypertension.

Post-operative care is critical. The dog must be closely monitored for complications, including seizures, which can occur as the liver begins to process toxins for the first time. Many dogs require continued medical management for several weeks or months after surgery while the liver regenerates.

### The Prognosis After Surgery

The prognosis for dogs with a single, surgically correctable shunt is generally good to excellent. Many dogs go on to live normal, healthy lives with no dietary restrictions or medications. However, the outcome depends on several factors, including the severity of the shunt, the presence of other liver abnormalities, and the skill of the surgeon.

Dogs that are managed medically have a more guarded prognosis. They require lifelong dietary and medication management and are at risk for recurring episodes of hepatic encephalopathy. However, with diligent care, many of these dogs can still enjoy a good quality of life for several years.

## Owner Observation and Preparation for the Veterinary Visit

The role of the owner in the diagnostic process cannot be overstated. Owners are the ones who observe the subtle changes in their dog's behavior and are often the first to notice that something is wrong. Being a prepared and observant owner can significantly expedite the diagnostic process.

### What to Document Before the Appointment

Before heading to the veterinary clinic, take some time to document your observations. This information will be invaluable to the veterinarian.

- **Video Recordings:** A video of your dog's tremors or neurological episodes is one of the most useful tools you can provide. It allows the veterinarian to see the exact nature of the problem, even if the dog is not showing signs during the appointment.
- **Timeline of Onset:** When did you first notice the signs? Were they sudden or gradual? Have they been constant or intermittent?
- **Triggers:** What seems to make the signs worse? Does eating, excitement, or stress seem to trigger an episode?
- **Response to Rest:** Do the signs improve when the dog is resting or sleeping?
- **Appetite and Weight:** Has your dog's appetite changed? Have you noticed any weight loss or failure to gain weight?
- **Bowel and Urinary Habits:** Have you noticed any changes in your dog's bowel movements or urination? Is there any straining or blood in the urine?
- **Behavioral Changes:** Have you noticed any changes in your dog's behavior, such as increased lethargy, staring, or disorientation?

### Questions to Ask Your Veterinarian

A veterinary visit can be overwhelming, and it is easy to forget questions in the moment. Preparing a list of questions beforehand can help ensure that you get the information you need.

- What is your tentative diagnosis, and what tests are needed to confirm it?
- What are the treatment options, and what are the risks and benefits of each?
- What is the expected prognosis for my dog?
- What signs should I watch for that would indicate an emergency?
- How will the treatment plan be adjusted over time?
- Are there any dietary or lifestyle changes I should make?

### The Importance of a Second Opinion

If your veterinarian is uncertain about the diagnosis or if your dog is not responding to treatment as expected, do not hesitate to seek a second opinion from a board-certified veterinary neurologist or internal medicine specialist. These specialists have advanced training and access to advanced diagnostic tools that may not be available in a general practice. A second opinion can provide peace of mind and ensure that your dog is receiving the best possible care.

## Prevention, Breeding Ethics, and Special Population Considerations

While owners cannot prevent these conditions in their individual dogs, they can play a role in reducing the incidence of these diseases in the breed as a whole.

### The Role of Responsible Breeding

Both White Shaker Syndrome and Portosystemic Shunt are believed to have a genetic component. Responsible breeders should be aware of the health history of their breeding dogs and should avoid breeding dogs that have been affected by these conditions. For PSS, breeders can screen their breeding stock with bile acid tests or advanced imaging to identify carriers. This is not a perfect system, but it can help to reduce the prevalence of these conditions over time.

### The Unique Challenges of Toy Breed Puppies

Maltese puppies are particularly vulnerable to hypoglycemia, which can mimic some of the signs of both WSS and PSS. Owners of toy breed puppies should be aware of the signs of low blood sugar, which include lethargy, weakness, tremors, and collapse. Feeding small, frequent meals and ensuring that puppies do not go too long without eating can help prevent this condition.

### Considerations for Senior Maltese Dogs

While WSS and PSS are typically diagnosed in young dogs, it is important to remember that senior Maltese dogs can also develop health problems. The aging process can affect the liver and the nervous system, and the signs of these conditions can overlap with the signs of age-related decline. A thorough veterinary evaluation is important for any senior dog showing changes in behavior, appetite, or mobility.

### The Financial and Emotional Commitment

Caring for a Maltese with WSS or PSS is a significant commitment. The diagnostic workup can be expensive, and the treatment, whether medical or surgical, requires ongoing financial investment. The emotional toll on the owner can also be considerable. It is important for owners to be prepared for this commitment and to have open and honest conversations with their veterinarian about the costs and expectations of treatment.

## The Evidence Base and Its Limitations

It is important to acknowledge that the understanding of both WSS and PSS is based on clinical experience and a growing body of research. However, there are limitations to the current evidence.

### The Lack of Definitive Genetic Markers

For both conditions, there is no commercially available genetic test that can definitively predict whether a dog will develop the disease. This limits the ability of breeders to make fully informed breeding decisions. Research is ongoing to identify the genetic mutations responsible for these conditions, but until then, breeders must rely on phenotypic screening and pedigree analysis.

### The Variability of Clinical Presentation

The clinical presentation of both WSS and PSS can vary significantly from dog to dog. Some dogs with WSS may have only mild tremors, while others may be severely affected. Some dogs with PSS may show only subtle signs, while others may present with life-threatening seizures. This variability can make diagnosis challenging and highlights the importance of a thorough and individualized approach to each case.

## Frequently Asked Questions

### What are the first signs of White Shaker Syndrome in a Maltese?
The first signs are usually fine, rapid tremors over the whole body that worsen with excitement or purposeful movement, like reaching for a toy. The dog remains alert and responsive.

### Is White Shaker Syndrome painful for dogs?
No, White Shaker Syndrome is not considered a painful condition. The tremors are a result of brain inflammation, but they do not cause discomfort to the dog.

### Can a Maltese live a normal life with White Shaker Syndrome?
Yes, with appropriate treatment, most dogs with White Shaker Syndrome can live a very good quality of life. Many require lifelong medication, but the tremors are well-controlled, and they can enjoy normal activities.

### What does a portosystemic shunt do to a dog?
A portosystemic shunt is an abnormal blood vessel that bypasses the liver. This allows toxins, like ammonia, to circulate in the blood and reach the brain, causing neurological signs like disorientation, head pressing, and seizures.

### What is the life expectancy of a dog with a liver shunt?
The life expectancy for a dog with a liver shunt depends on the treatment. With successful surgical correction, a dog can live a normal lifespan. With medical management alone, the prognosis is more guarded, and life expectancy may be shortened.

### How much does it cost to treat a portosystemic shunt in a dog?
The cost can vary widely depending on your location and the complexity of the case. Diagnostics like a CT scan and the surgery itself can be expensive, often ranging from $3,000 to $8,000 or more. Medical management is a lower upfront cost but requires lifelong medication and prescription diets.

### Are Maltese dogs prone to other health problems?
Yes, in addition to WSS and PSS, Maltese dogs can be prone to other conditions like patellar luxation, dental disease, and eye problems. The sources also note that a crossbred Maltese dog was diagnosed with hemophilia B, a bleeding disorder [<a href="#ref-1">1</a>].

### What should I do if I suspect my Maltese has a health problem?
You should schedule an appointment with your veterinarian immediately. Do not attempt to treat the condition at home. Early and accurate diagnosis is the most important step in managing any serious health issue.

## Sources

<a id="ref-1"></a>[<a href="#ref-1">1</a>] [Hemophilia B in a crossbred Maltese dog.](https://pubmed.ncbi.nlm.nih.gov/17146185/)

<a id="ref-2"></a>[<a href="#ref-2">2</a>] [Using Opera and the Performing Arts to Educate about Mental Health Problems - Ciklu.](https://pubmed.ncbi.nlm.nih.gov/36170743/)

<a id="ref-3"></a>[<a href="#ref-3">3</a>] [Oral health and dental care facilities in Maltese residential homes.](https://pubmed.ncbi.nlm.nih.gov/16163905/)

<a id="ref-4"></a>[<a href="#ref-4">4</a>] [The care and health needs of children in residential care in the Maltese Islands.](https://pubmed.ncbi.nlm.nih.gov/11350453/)

<a id="ref-5"></a>[<a href="#ref-5">5</a>] [Prevalence of Refractive Errors, Myopic Macular Degeneration, and Associated Risk Factors in a Maltese Population-Based Study.](https://pubmed.ncbi.nlm.nih.gov/41890681/)

<a id="ref-6"></a>[<a href="#ref-6">6</a>] [Health and medication literacy and the desire to participate in pharmacotherapy decision making - comparison of two countries.](https://pubmed.ncbi.nlm.nih.gov/29934278/)

<a id="ref-7"></a>[<a href="#ref-7">7</a>] [Health beliefs, illness perceptions and determinants of breast screening uptake in Malta: a cross-sectional survey.](https://pubmed.ncbi.nlm.nih.gov/28482828/)

<a id="ref-8"></a>[<a href="#ref-8">8</a>] [The mental health of newly graduated doctors in Malta.](https://pubmed.ncbi.nlm.nih.gov/23995187/)

<a id="ref-9"></a>[<a href="#ref-9">9</a>] [Children with Apert syndrome as adults: a follow-up study of 28 Scandinavian patients.](https://pubmed.ncbi.nlm.nih.gov/23018718/)

<a id="ref-10"></a>[<a href="#ref-10">10</a>] [Public perceptions of climate change as a human health risk: surveys of the United States, Canada and Malta.](https://pubmed.ncbi.nlm.nih.gov/20644690/)

<a id="ref-11"></a>[<a href="#ref-11">11</a>] [A computerized health screening and follow-up system in diabetes mellitus.](https://pubmed.ncbi.nlm.nih.gov/7758266/)

<a id="ref-12"></a>[<a href="#ref-12">12</a>] [Initial effects of Mental Health First Aid training on mental health literacy, social distance, stigma, mental health, and quality of life in the German adult population - Findings from a pilot study.](https://pubmed.ncbi.nlm.nih.gov/41140121/)

<a id="ref-13"></a>[<a href="#ref-13">13</a>] [The diabesity health economic crisis-the size of the crisis in a European island state following a cross-sectional study.](https://pubmed.ncbi.nlm.nih.gov/27999669/)

<a id="ref-14"></a>[<a href="#ref-14">14</a>] [A decrease in the prevalence and improved control of allergic conditions in 13- to 15-yr-old Maltese children (ISAAC).](https://pubmed.ncbi.nlm.nih.gov/20961337/)

<a id="ref-15"></a>[<a href="#ref-15">15</a>] [Irrigated agriculture and soil salinization in the Maltese islands.](https://pubmed.ncbi.nlm.nih.gov/12929809/)

<a id="ref-16"></a>[<a href="#ref-16">16</a>] [Risk factors for gestational impaired glucose tolerance in the Maltese population: a cross-sectional study.](https://pubmed.ncbi.nlm.nih.gov/12521775/)

<a id="ref-17"></a>[<a href="#ref-17">17</a>] [Asthma, rhinitis and eczema in Maltese 13-15 year-old schoolchildren -- prevalence, severity and associated factors [ISAAC]. International Study of Asthma and Allergies in Childhood.](https://pubmed.ncbi.nlm.nih.gov/9761012/)

<a id="ref-18"></a>[<a href="#ref-18">18</a>] [Retinopathy in Maltese type 2 diabetic patients.](https://pubmed.ncbi.nlm.nih.gov/7648810/)

## Related Clinical & Scientific Guides

* [Birman Health Problems: Inherited Conditions and Cardiac Screenings](/knowledge/veterinary-medicine/breed-specific-health/birman-health-problems-inherited-conditions-and-cardiac-screenings)
* [Singapura Cat Health Problems: Inherited Conditions and Cardiac Screenings](/knowledge/veterinary-medicine/breed-specific-health/singapura-cat-health-problems-inherited-conditions-and-cardiac-screenings)
* [Siberian Cat Health Problems: Inherited Conditions and Cardiac Screenings](/knowledge/veterinary-medicine/breed-specific-health/siberian-cat-health-problems-inherited-conditions-and-cardiac-screenings)