Portosystemic shunt

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Sections available in full article Introduction, Presenting signs, Acute presentation, Age predisposition, Breed predisposition, Cost considerations, Special risks (e.g. anesthetic), Pathogenesis, Etiology, Pathophysiology, Timecourse (incubation, duration), Diagnosis, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Initial symptomatic treatment, Standard treatment, Subsequent management, Prevention, Control, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Lori Ludwig DVM DipACVS
Synonyms Portocaval shunt, PSS.

Introduction

  • Cause : congenital or acquired vascular anomaly in which portal blood bypasses the liver → systemic circulation via portal vein.
  • Acquired - usually multiple-form secondary to liver disease/portal hypertension.
  • Young dogs (congenital cases).
  • Signs :
    • Small body stature.
    • Urinary : hematuria, dysuria, stranguria, obstruction.
    • Gastrointestinal : vomiting, diarrhea, anorexia, hepatic encephalopathy (stupor, head pressing, seizures, etc).
    • Neurologic.
  • Diagnosis : history, age, signs, laboratory tests, urinalysis, pre- and post-prandial bile acid analysis, radiography, ultrasonography, portography.
  • Treatment : surgical ligation of shunt. Medical management in acute cases prior to surgery, in long-term cases where surgery impossible/failed/declined by owners.
    Very susceptible to oral sedatives and anesthetics.
  • Prognosis : good following surgery or with careful management.

Diagnosis

Clinical signs

  • Depression.
  • Ataxia.
  • Seizures.
  • Coma/stupor.
  • Pacing/circling.
  • Hyperactivity.
  • Muscle tremors.
  • Head pressing.
  • Pyrexia.
  • Urolithiasis.
  • Liver small or not palpable.
  • Fluid thrill (ascites) - only in aquired cases.
  • Muffled heart sounds (pleural effusion).
  • Enlarged kidney.

Diagnosis

Differential diagnosis

  • Microvascular dysplasia.
  • Hepatic arteriovenous fistula.
  • Hepatic cirrhosis Liver: cirrhosis.
  • Chronic hepatitis Liver: chronic hepatitis.
  • Toxic hepatitis (acute) Liver: toxic hepatitis.
  • Infectious hepatitis - leptospirosis Leptospirosis , infectious canine hepatitis (acute) Canine adenovirus type 1 disease.
  • Other non-hepatic diseases - hydrocephalus, epilepsy, distemper (neurological signs).
  • Biliary tract disease Liver: cholangiohepatitis - hypoglycemia.

Sequelae

Prognosis

  • Good: if surgery successful.
  • Reasonable: if managed medically - can survive long periods. Recurrences up to 2 years post-surgery require continued assesment.

Expected response to treatment

  • Resolution of neurological signs, urinary tract signs or vomiting/diarrhea.
  • Weight gain.
  • Improvement in clinical signs after discontinuing medical treatment (if surgically corrected).

Reasons for treatment failure

  • Formation of multiple extrahepatic shunts post-operatively.
  • Failure to locate or ligate shunting vessel(s).
  • Acute portal hypertension following surgery.
  • If partial ligation performed, approximately 50% will develop long-term complications (recurrence of signs) unless completely ligated.
  • Failure to respond to medical management.

Sources

Publications

Refereed papers

  • van Straten G, Leegwater P A J, de Vries M, van den Brom W E & Rothuizen J (2005) Inherited congenital extrahepatic portosystemic shunts in Cairn terriers. J Vet Intern Med 19 , 321-324 PubMed.
  • Mehl M L et al(2005) Evaluation of ameroid ring contrictors for treatment for single extrahepatic portosystemic shunts in dogs: 168 cases (1995-2001). JAVMA 226 (12), 2020-2030 PubMed
  • Szatmari V et al(2004) Ultrasonographic evaluation of partially attenuated congenital extrahepatic portosystemic shunts in 14 dogs. Vet Rec 155 , 448-456.
  • Murphy S T, Ellison G W, Long M & Van Gilder J (2001) A comparison of the ameroid constrictor versus ligation in the surgical management of single extrahepatic portosystemic shunts. JAAHA 37 (4), 390-396.
  • Gonzalo-Orden J M et al(2000) Transvenous coil embolization of an intrahepatic portosystemic shunt in a dog. Vet Rad Ultra 41 (6), 516-518.
  • Tisdall P L C, Hunt G B, Youmans K R & Malik R (2000) Neurological dysfunction in dogs following attenuation of congenital extrahepatic portosystemic shunts. JSAP 41 , 539-546.
  • Heldmann E et al(1999) Use of propofol to manage seizure activity after surgical treatment of portosystemic shunts. JSAP 40 (12), 590-4.
  • Kerr M G & van Doorn (1999) Mass screening of Irish Wolfhound puppies for portosystemic shunts by dynamic bile acid test. Vet Rec 144 , 609-696.
  • Vogt J C, Krahwinkel K G, Bright R M et al(1996) Gradual occlusion of extrahepatic portosystemic shunts in dogs and cats using the ameroid constrictor. Vet Surg 25 (6), 495-502.
  • Bostwick D R, Twedt D C (1995) Intrahepatic and extrahepatic portal venous anomalies in dogs - 52 cases (1982-1992). JAVMA 206 , 1181-1185.
  • Komtebedde J et al(1995) Long-term clinical outcome after partial ligation of single extrahepatic vascular anomalies in 20 dogs. Vet Surg 24 , 2379.
  • Hotl D (1994) Critical care management of the portosystemic shunt patient. Comp Cont Ed Pract Vet 16 , 879-892.
  • Daniel G B, Bright R, Ollis P et al(1991) Per rectal portal scintigraphy using 99mtechnetium pertechnetate to diagnose portosystemic shunts in dogs and cats. JVIM 5 , 23-27.
  • Johnson C A, Armstrong P J, Hauptman J W (1987) Congintal portosystemic shunts in dogs - 46 cases (1979-1986). JAVMA 191 , 1478-1483.

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