Caval Syndrome in Dogs

Caval Syndrome in Dogs

Health & Safety

Caval syndrome is a very serious condition that arises as a result of a dog suffering from heartworm. It is a complication that develops due to an overload of the worms dropping into a dog's right ventricle causing a blockage that can end up being life-threatening because it causes such a serious obstruction in a dog’s heart. However, when dogs develop Caval syndrome it can also seriously impact other vital organs too.

Symptoms Associated with the Condition

When dogs develop Caval syndrome there are certain symptoms associated with the condition that are quite different to those connected to heartworm. The signs there is something wrong are as follows:

  • Acute anorexia
  • Difficulty breathing
  • Coughing
  • Loss of appetite
  • Jaundice
  • Fever
  • Pale gums and other mucous membranes
  • Weakness
  • Lethargy
  • Heart murmur
  • Anaemia
  • Haemoglobinuria
  • Liver dysfunction
  • Kidney issues
  • Heart failure
  • Disseminated intravascular coagulation (DIC)

The Causes

As previously mentioned, dogs develop Caval syndrome as a result of suffering from heartworm. The overload of worms drop into a dog's right heart ventricle which then causes a blockage and backflow of blood. It is a life-threatening condition where the parasites can survive for up to seven years in the host. The worms can also then migrate to other organs and to a dog's lungs, their liver and kidneys causing a tremendous amount of damage**.**

Diagnosing the Condition

A vet would ideally need to know a dog's full medical history and how the onset of any symptoms first presented themselves. The vet would then check to see if a dog is suffering from an overload of heartworms. The sort of test a vet would typically recommend carrying out which would help confirm a diagnosis would include the following:

  • A complete blood count
  • A full biochemistry profile
  • X-rays of a dog's chest
  • Echocardiography
  • Electrocardiography
  • Ultrasound
  • A Knott's test
  • ELISA test

The vet would also want to make sure a dog's liver and kidneys are functioning as they should before they would set in place any sort of treatment.

Treatment Options

The treatment options available depend on the severity of a dog's condition. With this said, the more advanced the condition is when first diagnosed, the poorer the prognosis tends to be for dogs when they are suffering from Caval syndrome. Should a dog not be given the necessary treatment, they typically succumb to their symptoms very quickly which can be anything from 24 to 72 hours after they first presented themselves.

A vet would need to surgically remove the worms found in a dog's right ventricle before they could set in place a treatment, but even when the worms are removed, a dog may suffer organ failure which results in their death. Only after the overload of worms have been removed, the vet would need to treat a dog's liver disease, kidney dysfunction and heart condition before they would be able to treat them for the heartworm problem.

Dogs need a tremendous amount of supportive care during their treatment which includes being given vital fluids intravenously both before and after they have had the necessary surgery to remove the worms from their hearts. Dogs need to be hospitalised so their condition can be closely monitored and so they can be given oxygen if their breathing has been compromised.

Once a dog's condition has been stabilised, they would be allowed to go home but would still need to be given a tremendous amount of supportive care during their recovery period. The vet would also want to check on a dog's condition 4 to 6 months later which would be to establish the level of adult heartworms that may still be present in a dog's system and if this is the case to prescribe a necessary treatment to kill them off. In many cases, dogs need to be given medication for the remainder of their lives but this would depend on how severe their condition was when first diagnosed and treated.


The only way of preventing heartworm in dogs is to make sure they are well protected in the first place. As such anyone taking their dog abroad to a country where mosquitoes are a real problem should make sure their dogs are kept away from known infested areas and to use a spot treatment on their dogs to make sure they are as protected as possible. A vet would be able to prescribe heartworm pills that are known to be an effective way of preventing a dog from developing heartworm. The pills need to be given to a dog on a monthly basis and would provide the necessary protection against heartworm and thus reducing the risk of them developing Caval Syndrome.



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