Caval syndrome

From Dog

Caval syndrome is a rare heart disease of dogs characterised by acute heart failure due to heartworm disease.

In this syndrome, a heavy burden of Dirofilaria immitis results in movement of worms from the right ventricle into the right atrium and vena cava, resulting in vascular obstruction, turbulence and thromboembolism. Circulatory failure can occur, followed in neglected cases with acute death[1].

In rare cases, caval syndrome can also occur consequent to adulticidal therapy, causing dead worms to be flushed into the vena cava[2].

Acute cases need to be treated as medical emergencies, often necessitating surgical removal of worms by percutaneous vena caval catherisation[3].


  1. Atkins C (2005) Canine heartworm disease. In: Ettinger SJ, Feldman EC, editors. Textbook of Veterinary Internal Medicine. 6th ed. St. Louis: Saunders. pp:1118–1136
  2. Kittleson MD (1998) Heartworm infestation and disease (dirofilariasis) In: Kittleson MD, Kienle RD, editors. Small Animal Cardiovascular Medicine. 1st ed. St. Louis: Mosby. pp:370–401
  3. Yoon WK et al (2011) Catheter-guided percutaneous heartworm removal using a nitinol basket in dogs with caval syndrome. J Vet Sci 12(2):199-201