Heartworm in Ferrets

By PetMD Editorial on Aug. 11, 2008

Dirofilaria immitis Parasite

Heartworm disease is a dangerous parasitic infection that is transmitted by mosquitoes. The worm, a Dirofilaria immitis parasite, lodges itself in the pulmonary artery of the ferret's heart and grows, causing the organ to increase in size, high blood pressure and/or blood clots (much like in dogs). It may be seen in ferrets at any age, and is usually more common in tropical and semi-tropical zones. Also, infections consisting of very few worms (one to two adults) is sufficient enough to cause severe heart disease (and death) in ferrets.

Symptoms and Types

Because the heartworm(s) disturbs the normal function of the ferret's heart and circulatory system, these are some symptoms which may be present:

  • Rapid heart beat
  • Weakness
  • Loss of appetite
  • Depression
  • Weight loss and muscle wasting
  • Fluid accumulation in the abdomen or chest

In addition, heartworm disease affects the distribution of blood to the lungs, leading to such breathing difficulties as:

  • Coughing
  • Shortness of breath
  • Rapid breathing
  • Rales or crackles (clicking, rattling, or crackling noises heard during inhalation)


This disease occurs when the ferret becomes infected with D. immitis, usually transmitted through a bite from a mosquito carrying the parasite.


This is not an easy disease to diagnose. However, the heartworm antigen test, which detects adult heartworm skin in the animal's blood, appears to be the most useful. An echocardiogram can produce a picture of the ferret's heart and help identify any heartworms, too.


The veterinarian will be focused on killing off the worms, followed by treatment to increase lung function -- generally done with an anti-parasite and prednisone medication combo. Worm-killing therapy carries the risk of complications from drug toxicity and worm emboli (a blocking of blood vessel). However, treatment with long-term anti-parasite medication and prednisone kills off the heartworms more slowly, making the chances of a worm emboli less likely.

It is important to restrict the animal's activity for at least four to six weeks once the treatment has begun.

If the ferret is suffering from severe heart problems or failure, it will need to be hospitalized and stabilized. The chest may also need to be tapped to remove any fluid that could have accumulated.


Preventative medicine like selamectin or ivermectin should be given to ferrets who live in a high risk area and are allowed outside. In addition, eliminating mosquitoes from the ferret’s environment can help prevent heartworm disease.

Living and Management

After recovery, it is important to follow-up with immunization treatment. The veterinarian will also want to perform an antigen test three to four weeks after the medications are administered, and chest X-rays may be needed periodically to follow the ferret's progress.

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