ISSN 2398-2969      

Congenital portosystemic shunt (CPSS)


Synonym(s): Portocaval shunt, PSS


  • Cause: congenital vascular anomaly connecting the portal blood system to the systemic circulation. This allows blood from the gastrointestinal tract to bypass the liver.
  • Primarily young dogs.
  • Signs:
    • Central nervous system signs: altered behavior, head pressing, blindness, ataxia, seizures.
    • Gastrointestinal signs: vomiting, diarrhea, anorexia, melena.
    • Urinary tract signs: hematuria, dysuria, stranguria, obstruction.
    • Other: small body stature, poor weight gain, polyuria/polydipsia, intolerance to sedatives and anesthetic drugs.
  • Diagnosis: history, age, clinical signs, pre- and post-prandial bile acids, ultrasonography, intra-operative mesenteric portovenography, CT angiography, MRI angiography.
  • Treatment: attenuation of shunt (ligation, ameroid constrictor, cellophane band, hydraulic occluder, interventional radiology). Medical management prior to surgery or in long-term cases where surgery impossible/failed/declined by owners.
  • Prognosis: good if surgery successful or with careful medical management in some dogs. Long term survival better for surgically managed dogs.
    Print off the owner factsheet on Congenital portosystemic shunt to give to your client.



  • Congenital anomalies that can take two forms:
    • Extrahepatic:
      • More common.
      • Abnormal vessel branches from portal vein or tributary before it enters the liver.
      • Portocaval CPSS are the most common in the dog. Other forms include porto-azygous, left gastric/splenic and colonic.
      • Represents an abnormal functional communication between the vitelline and cardinal venous systems.
    • Intrahepatic:
      • Arises from an intrahepatic portal vein branch and thus lies wholly or partly within the liver parenchyma.
      • Classified according to division of the liver that is affected - left, right or central.
      • Left CPSSs typically take the form of a patent ductus venosus (PDV) which results from failure of the ductus venosus to close following birth.
      • The origin of other forms of intrahepatic shunts is unclear.


  • Abnormal communication between portal and systemic blood systems allows blood containing toxic or harmful substances to bypass liver where they would normally be metabolized. This results in increased levels of toxins in the systemic circulation leading to hepatic encephalopathy.
    • Clinical signs relating to central nervous system.
    • Multifactorial - factors act synergistically.
    • Ammonia is major factor in hepatic encephalopathy. Produced from urea by anaerobic bacteria in gastrointestinal tract (colon).
    • Other factors include aromatic amino acids (phenylalanine, tyrosine, tryptophan and methionine), central nervous system inhibitors (GABA and GABA receptors), mercaptans and short chain fatty acids.
    • Signs of hepatic encephalopathy can be triggered by a high protein meal, gastrointestinal bleeding or the use of sedative or anesthetic drugs.
  • Reduced hepatic blood supply results in a failure of normal liver growth and development and results in functional hepatic insufficiency:
    • Abililty to metabolize uric acid reduced. This results in increased serum ammonia and uric acid which are excreted in the urine. Ammonium biurate crystals form and can cause lower urinary tract signs.
    • Hypoalbuminemia Hypoproteinemia.
    • Intermittent hypoglycemia.
    • Electrolyte abnormalities.
    • Stunted growth.


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Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Tivers M S, Upjohn M M, House A K, Brockman D J & Lipscomb V J (2012) Treatment of extrahepatic congenital portosystemic shunts in dogs - what is the evidence base? JSAP 53, 3-11 PubMed.
  • Greenhalgh S N, Dunning M D, McKinley T J, Goodfellow M R, Kelman K R, Freitag T, O'Neill E J, Hall E J, Watson P J & Jeffery N D (2010) Comparison of survival after surgical or medical treatment in dogs with a congenital portosystemic shunt. JAVMA 236, 1215-1220 PubMed.
  • Hogan D F, Benitez M E, Parnell N K, Green H W 3rd & Sederquist K (2010) Intravascular occlusion for the correction of extrahepatic portosystemic shunts in dogs. JVIM 24, 1048-1054 PubMed.
  • Berent A C & Tobias K M (2009) Portosystemic Vascular Anomalies. Vet Clin North Am Small Anim 39, 513-541 PubMed.
  • Zwingenberger A (2009) CT diagnosis of portosystemic shunts. Vet Clin North Am Small Anim Pract 39, 783-792 PubMed.
  • Bussadori R, Bussadori C, Millan L, Costilla S, Rodriguez-Altonaga J A, Orden M A & Gonzalo-Orden J M (2008) Transvenous coil embolisation for the treatment of single congenital portosystemic shunts in six dogs. Vet J 176, 221-226 PubMed.
  • Landon B P, Abraham L A & Charles J A (2008) Use of transcolonic portal scintigraphy to evaluate efficacy of cellophane banding of congenital extrahepatic portosystemic shunts in 16 dogs. Aust Vet J 86, 169-179; quiz CE161 PubMed.
  • Frankel D, Seim H, MacPhail C & Monnet E (2006) Evaluation of cellophane banding with and without intraoperative attenuation for treatment of congenital extrahepatic portosystemic shunts in dogs. JAVMA 228, 1355-1360 PubMed.
  • Kummeling A, Teske E, Rothuizen J & Van Sluijs F J (2006) Coagulation profiles in dogs with congenital portosystemic shunts before and after surgical attenuation. JVIM 20, 1319-1326 PubMed.
  • Lee K C, Lipscomb V J, Lamb C R, Gregory S P, Guitian J & Brockman D J (2006) Association of portovenographic findings with outcome in dogs receiving surgical treatment for single congenital portosystemic shunts: 45 cases (2000-2004). JAVMA 229 (7), 1122-1129 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.
  • Hunt G B, Kummeling A, Tisdall P L, Marchevsky A M, Liptak J M, Youmans K R, Goldsmid S E & Beck J A (2004) Outcomes of cellophane banding for congenital portosystemic shunts in 106 dogs and 5 cats. Vet Surg 33, 25-31 PubMed.
  • Kummeling A, Van Sluijs F J & Rothuizen J (2004) Prognostic implications of the degree of shunt narrowing and of the portal vein diameter in dogs with congenital portosystemic shunts. Vet Surg 31, 561-570 PubMed.
  • Hurn S D & Edwards G A (2003) Perioperative outcomes after three different single extrahepatic portosystemic shunt attenuation techniques in dogs: partial ligation, complete ligation and ameroid constrictor placement. Aust Vet J 81 (11), 666-670 PubMed.
  • Leveille R, Johnson S E & Birchard S J (2003) Transvenous coil embolization of portosystemic shunt in dogs. Veterinary Radiology and Ultrasound 44, 32-36 PubMed.
  • Winkler J T, Bohling M W, Tillson D M, Wright J C & Ballagas A J (2003) Portosystemic shunts: diagnosis, prognosis, and treatment of 64 cases (1993-2001). JAAHA 39 (2), 169-185 PubMed.
  • Papazoglou L G, Monnet,E & Seim H B (2002) Survival and prognostic indicators for dogs with intrahepatic portosystemic shunts: 32 cases (1990-2000). Vet Surg 31 (6), 561-570 PubMed.
  • Burton C A & White R N (2001) Portovenogram findings in cases of elevated bile acid concentrations following correction of portosystemic shunts. JSAP 42 (11), 536-540 PubMed.
  • 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 PubMed.
  • Hunt G B & Hughes J (1999) Outcomes after extrahepatic portosystemic shunt ligation in 49 dogs. Aust Vet J 77, 303-307 PubMed.
  • Seguin B, Tobias K M, Gavin P R & Tucker R L (1999) Use of magnetic resonance angiography for diagnosis of portosystemic shunts in dogs. Veterinary Radiology and Ultrasound 40 (3), 251-258 PubMed.
  • Watson P J & Herrtage M E (1998) Medical management of congenital portosystemic shunts in 27 dogs- a retrospective study. JSAP 39 (2), 62-68 PubMed.
  • White R N, Burton C A & McEvoy F J (1998) Surgical treatment of intrahepatic portosystemic shunts in 45 dogs. Vet Rec 142, 358-365 PubMed.
  • Youmans K R & Hunt G B (1998) Cellophane banding for the gradual attenuation of single extrahepatic portosystemic shunts in eleven dogs. Aust Vet J 76 (8), 531-537 PubMed.
  • Hunt G B, Bellenger C R & Pearson M R B (1996) Transportal approach for attenuating intrahepatic portosystemic shunts in dogs. Vet Surg 25 (4), 300-308 PubMed.
  • 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 PubMed.
  • Bostwick D R & Twedt D C (1995) Intrahepatic and extrahepatic portal venous anomalies in dogs - 52 cases (1982-1992). JAVMA 206 (8), 1181-1185 PubMed.
  • Hottinger H A, Walshaw R & Hauptman J G (1995) Long-Term Results of Complete and Partial Ligation of Congenital Portosystemic Shunts in Dogs. Vet Surg 24 (4), 331-336 PubMed.
  • Komtebedde J, Koblik P D, Breznock E M, Harb M & Garrow L A (1995) Long-Term Clinical Outcome after Partial Ligation of Single Extrahepatic Vascular Anomalies in 20 Dogs. Vet Surg 24 (5), 379-383 PubMed.
  • Smith K R, Bauer M & Monnet E (1995) Portosystemic Communications - Follow-up of 32 Cases. JSAP 36 (10), 435-440 PubMed.
  • Holt D (1994) Critical care management of the portosystemic shunt patient. Comp Cont Ed Pract Vet 16 (7), 879-892 VetMedResource.
  • Tisdall P L C, Hunt G B, Bellenger C R & Malik R (1994) Congenital Portosystemic Shunts in Maltese and Australian Cattle Dogs. Aust Vet J 71 (6), 174-178 PubMed.
  • Lawrence D, Bellah J R & Diaz R (1992) Results of Surgical-Management of Portosystemic Shunts in Dogs - 20 Cases (1985-1990). JAVMA 201 (11), 1750-1753 PubMed.
  • Swalec K M & Smeak D D (1990) Partial Versus Complete Attenuation of Single Portosystemic Shunts. Vet Surg 19 (6), 406-411 PubMed.
  • Mathews K & Gofton N (1988) Congenital Extrahepatic Portosystemic Shunt Occlusion in the Dog - Gross Observations during Surgical-Correction. JAAHA 24 (4), 387-394 VetMedResource.
  • Johnson C A, Armstrong P J & Hauptman J G (1987) Congenital portosystemic shunts in dogs: 46 cases (1979-1986). JAVMA 191 (11), 1478-1483 PubMed.
  • Breznock E M (1979) Surgical manipulation of portosystemic shunts in dogs. JAVMA 174 (8), 819-826 PubMed.

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