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Extrahepatic Portosystemic Shunt, or EH-PSS

EH-PSS in cats and dogs can lead to several health problems due to the diversion of blood around the liver, impairing its normal metabolic and detoxifying functions.

What is an Extrahepatic Portosystemic Shunt?

A portosystemic shunt (PSS) is an abnormal vascular connection between the portal vein, which carries blood from the digestive organs to the liver, and the systemic circulation, bypassing the liver. When this occurs outside the liver, it is referred to as an extrahepatic portosystemic shunt (EH-PSS).

What causes EH - PSS?

EH-PSS can be congenital (present at birth) or acquired. Congenital shunts are more common in small dog breeds, such as Yorkshire Terriers and Maltese, while acquired shunts may occur secondary to liver disease or liver damage.



What are the symptoms of EH - PSS?

The clinical signs of EH-PSS can vary depending on the severity of the shunt, but they commonly include:


Neurological Signs: Cats and dogs with EH-PSS may exhibit neurological abnormalities, such as disorientation, seizures, head pressing, circling, behavioral changes, or poor coordination.


Stunted Growth: Young animals with EH-PSS may experience poor growth or failure to thrive.


Digestive Issues: Symptoms can include decreased appetite, vomiting, diarrhea, or increased thirst and urination.


Urinary Issues: Cats and dogs with EH-PSS may develop urinary tract problems, such as bladder stones or urinary tract infections.

How is EH - PSS diagnosed?

Diagnosing EH-PSS requires a combination of clinical signs, medical history, and diagnostic tests, including:


Physical Examination: The veterinarian will conduct a thorough physical examination to assess the overall health of the cat or dog and identify any specific signs that may indicate a shunt.


Blood Tests: Blood work can reveal abnormal liver function, such as elevated liver enzymes or altered bile acid levels, which can support the diagnosis.


Imaging Studies: Radiographs (X-rays) or ultrasound examinations can help identify the shunt and determine its location and severity.


Contrast Radiography or CT Scan: These imaging techniques may be employed to provide detailed visualization of blood flow and identify the exact location of the shunt.


Nuclear Scintigraphy: In some cases, nuclear scintigraphy, which involves injecting a radioactive tracer into the bloodstream, may be used to detect the shunt and assess blood flow.

What is the treatment for pets with EH - PSS?

The primary treatment for EH-PSS is surgical correction, which involves closing or redirecting the abnormal blood vessel connection.  The surgical options include:


Ligation: The shunt vessel is surgically tied off or ligated to prevent the flow of blood.


Ameroid Constrictor Placement: An ameroid constrictor, a constrictive device, is placed around the shunt vessel. Over time, it gradually closes the vessel, allowing normal blood flow.


Surgical Attenuation: In some cases, the shunt vessel is partially closed or redirected to gradually normalize blood flow.

What is the post-operative care for the surgical correction of EH - PSS?

What is the prognosis for pets with EH - PSS? 

After surgery, the cat or dog will require intensive post-operative care, including:


Hospitalization: The animal may need to be hospitalized for a period of time to monitor their condition and provide necessary medical support.


Medications: Medications such as antibiotics, pain relievers, and medications to support liver function may be prescribed.


Dietary Management: A specialized diet that is low in protein and contains easily digestible nutrients may be recommended to reduce the workload on the liver.


Follow-up Care: Regular follow-up visits will be necessary to monitor the pet's progress, assess liver function, and make any necessary adjustments to the treatment plan.

The prognosis for cats and dogs with EH-PSS varies depending on several factors, including the severity of the shunt, the presence of concurrent health conditions, and the promptness of diagnosis and treatment.


Surgical correction of the shunt can lead to a significant improvement in clinical signs and overall quality of life. However, it is important to note that some animals may still experience residual neurological abnormalities even after successful surgery.


It is essential to consult a qualified veterinarian for a proper diagnosis, treatment options, and guidance tailored to the specific needs of your cat or dog with EH-PSS.

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