"Caval Syndrome in Cats

"Caval Syndrome in Cats

Health & Safety

Caval syndrome is a nasty condition that's linked to heartworm. The condition affects a certain percentage of cats that suffer from heartworm although more research is needed to establish just how high this percentage actually is. Caval syndrome can turn into a life-threatening condition, but it is not known why at times such a mass of worms manage to fall into the right ventricle of a cat's heart which then causes all the problems.

The Causes

As previously mentioned the condition arises as a result of a cat having developed heartworm. The problem starts when there is an overload of worms and because of the lack of space, a mass of them fall into a cat's right ventricle where they start to wind around the area of the heart called the tricuspid valve apparatus. When this happens, cats show symptoms of there being something wrong which are quite different to those associated with heartworm.

The heartworms cause what is termed as tricuspid regurgitation which is when the heart's valve is unable to close as it should. This means blood can flow backwards into a cat's right upper chamber as soon as the right lower chamber contracts. The fact that blood flow is interrupted causes all the problems and because the worms form an obstruction, it can prove life threatening. The condition is also referred to as liver failure syndrome"" because a cat's liver is often so negatively impacted by the condition.

The Symptoms Associated with the Condition

When cats develop caval syndrome, there are certain signs to watch out for that something is wrong. The symptoms most commonly associated with the condition are as follows:

  • Jaundiced looking eyes
  • Blood in urine - a condition known as haematuria
  • Pale gums and other mucous membranes
  • Low femoral pulse pressure
  • Anaemia
  • Elevated levels of liver enzymes
  • Heart murmur
  • Collapse

Diagnosing the Condition

A vet would ideally need to know a cat's full medical history and how the onset of any symptoms first presented themselves. The vet would thoroughly examine a cat suspected of having developed caval syndrome and would typically recommend carrying out the following tests to confirm a diagnosis:

  • Ultrasound - to establish whether heartworms have caused a blockage in a cat's heart

Treatment Options

When cats develop caval syndrome as a result of having heartworms, they have to be treated quite differently which means the heartworms need to be surgically removed before a treatment can be set in place. When a cat's condition is diagnosed as being ""acute"", the procedure must be done as a matter of urgency and a cat would need to be given general anaesthetic for the surgery to be carried out.

Cats need a lot of supportive care once the worms have been successfully removed from their hearts which means they typically need to remain hospitalised so they can be closely monitored. They would also need to be given fluid therapy to ensure their hearts are able to function properly. Vets would also typically prescribe corticosteroids and a course of antibiotics to fight off the risk of infection or to keep on top of an infection if it has already flared up.


The prognosis for cats suffering from caval syndrome tends to be quite guarded. Sadly, the mortality rate for cats with the condition is high with many experiencing organ failure even after they have been treated sooner rather than later for caval syndrome and the procedure was successfully carried out.


Newsletter icon
Get free tips and resources delivered directly to your inbox.


Pets for StudWanted Pets

Accessories & services


Knowledge Hub


Support & Safety Portal
All Pets for Sale