How do you manage congenital portosystemic shunts?

How do you manage congenital portosystemic shunts?

Jun 01, 2003

Signalment: Canine, Golden Retriever, 4 months old, female, 28 pounds.

Clinical history: The puppy presents for vaccinations and has a potbelly.

Image 1.
Physical examination: The findings include rectal temperature 102.2° F, heart rate 144/min, pink mucous membranes and normal capillary refill time. The puppy's panting and breathing made it difficult to actually hear the lung and heart sounds, but a grade 2/6 heart murmur is heard. The abdominal distension is noted to be palpable ascites. Abdominocentesis reveals clear fluid. The ECG shows a normal sinus rhythm.

Laboratory results: A complete blood count, serum chemistry profile and urinalysis were performed and are presented in Table 1.

Radiograph examination: The lateral abdominal radiograph shows the presence of severe ascites. The thoracic portion of the radiograph appears to be normal.

Ultrasound examination: Thorough thoracic and abdominal ultrasonography was performed.

Image 2.
Comments: There is a moderate amount of accumulated free fluid with fibrin tags present within the abdominal cavity. The liver shows a uniform echogenicity in its parenchyma. No masses noted within the liver parenchyma. The gall bladder is moderately distended, and its walls are not thickened or hyperechoic. The spleen shows a uniform echogenicity - no masses noted. The left and right kidneys are similar in size, shape and echotexture. No masses or calculi were noted in either kidney. The urinary bladder is distended with urine and contains some urine sediment material - no masses or calculi noted. The left and right adrenal glands are similar in size and shape. The stomach, small intestine and pancreatic region are normal. The echocardiogram is normal -- all heart valves are normal and Doppler flow across the pulmonary and aortic valves is normal.

Case management: In this case, congenital portosystemic shunt is the clinical diagnosis. At this point, this puppy should be followed up with defining whether intrahepatic shunt or extrahepatic shunt is present.

Image 3.
Congenital portosystemic shunt Congenital portosystemic shunts in puppies are usually single anomalous vessels in extrahepatic or intrahepatic locations. The consequences of the anomalous portal circulation are the portal blood contains toxins absorbed from the intestines that are delivered directly to the systemic circulation without benefit of hepatic detoxification, contributing to signs of hepatic encephalopathy and hepatotrophic factors in the visceral circulation. Draining the gastrointestinal tract and pancreas do not circulate directly to the liver, causing inadequate liver development and reduced functional liver tissue.

Signs of hepatic dysfunction associated with congenital portosystemic shunt are usually exhibited at a young age. Puppies may exhibit signs as early as 6- to 8-weeks of age. The signs in puppies are variable but may include vomiting, diarrhea, anorexia, small body stature, weight loss, intermittent fever, polyphagia, polydipsia, hematuria, hypersalivation, intolerance to anesthetic agents or tranquilizers that require hepatic metabolism or excretion, atypical behavior, and rarely ascites or icterus.

Image 4.
Intermittent neurologic abnormalities associated with ingestion of protein-laden food or resolving hemorrhage are common and may include episodic aggression, amaurosis, ataxia, incessant pacing, circling, head pressing and seizures. Some puppies are presented with ammonium biurate uroliths located in the urinary tract.

Definitive diagnosis of congenital portosystemic shunt in puppies is often not possible by routine laboratory evaluations. The CBC, serum chemistry profiles and urinalysis may help rule out other causes of presenting signs such as acute renal failure, electrolyte derangements, hypoglycemia and urinary tract disorders.