Cor Triatriatum Dexter

Cor triatriatum, also called cor triatrium, is an uncommon malformation caused by the division of the right or left heart atrium into two chambers by an abnormal membrane. Cor triatriatum sinister has been reported in cats and cor triatriatum dexter in dogs. In cor triatriatum dexter, the right atrium is partitioned into two compartments, effectively creating a triatrial heart. It is well documented in dogs. Affected breeds include Chow Chow, Cocker Spaniel, English Bulldog, German Shepherd Dog, German Shorthaired Pointer, Golden Retriever, Greyhound, Rottweiler, and mixed breed.

Cor triatriatum causes obstruction of venous flow through the atrium. In cor triatriatum dexter, the membrane occurs between the caudal vena cava and the tricuspid valve.6 The most common clinical sign is ascites. Another common sign is enlargement of the liver.3 Exercise intolerance, lethargy, fainting, distended abdominal veins, coughing, breathing problems, growth retardation and sometimes diarrhea have been reported in affected animals. Some dogs may have few or no symptoms. Successful therapy requires removal of the abnormal membrane to eliminate blood flow obstruction.2

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Although several methods have been used to treat cor triatriatum dexter in dogs, the surgical correction is considered the most reliable approach. It can be successfully treated by balloon dilatation provided that it is recognized early enough.4 Clinical signs improve within days and are sustained in the long term.

Cor Triatriatum Dexter in dogs


  1. Magnus Michaelsson, Siew Yen Ho. Congenital Heart Malformations in Mammals: An Illustrated Text
  2. Richard W. Nelson, C. Guillermo Couto. Small Animal INternal Medicine
  3. Cor triatriatum dexter in an English Bulldog puppy: case report and literature review. Robert B. Duncan, Jr., Larry E. Freeman, Jeryl Jones, Martha Moon
  4. Skrzypczak, P., Pasawska, U., Atamaniuk, W., Nicpon, J. Diagnosis and treatment of cor triatriatum dexter in dogs
  5. Merck vet Manual. Miscellaneous Congenital Cardiac Abnormalities
  6. Douglas H. Slatter (editor). Textbook of Small Animal Surgery

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