Heartworm in Cats (and Ferrets)

Heart worm is caused by footlong worms which live in the heart, lungs and blood vessels, causing damage to organs;   especially the lungs and the heart.   The worms affect cats, dogs, ferrets, wild animals like wolves, coyotes, foxes and even Sea Lions. Humans can be effected also, but rarely. I’m including wildlife, as many foxes and coyotes live near humans and are carriers of the disease.

We hear a lot about heart worm in dogs, but what about cats?  Heart worm is not the same in cats.  Most of the worms don’t survive to the adult stage. Cats may only have two or three adult worms.  Much of the time the disease goes unnoticed.  It’s the immature worms that really affect cat health.  It’s called “HARD” – Heartworm associated respiratory disease.  The medication for dogs can’t be used on cats, so prevention is the best medicine.


In looking at signs of heart worms in cats,  it can be somewhat difficult to detect.  Coughing, asthma-like attacks, periodic vomiting, lack of appetite,and weight lose are the general indications.  Others may be difficulty walking, seizures, fainting or fluid accumulation in the abdomen.  The ultimate first signs are sudden collapse and death, being a very sad ending.


Antigen and antibody tests are the preferred methods in screening cats for heartworm.  X-rays or ultrasounds may also be used.  Cats should be tested before using a preventative and retested per your vet to document continued exposure and risk.  Preventative is crucial to keep cats healthy.

What do I do if my  cat has heartworm?  There is no drug approved therapy for heartworm positive cats.  Sometimes it may “fix” itself.  Good vet care to stablelize  your cat and to determine a long-term management plan is indicated.  Therapy may include fluids, general nursing care, drugs to treat lung and heart symptoms and even surgery to remove the worms.



Like cats, Ferrets have the same parasite that causes heartworm.  Due to their size though, one worm can be devastating to them.  They are very susceptible to the infection more than cats. The diagnosis is difficult and there is no preventative or approved treatment.  Only care and prevention are very important to keep your Ferret healthy.


What are the signs of Heart worm? Being quite small, the ferret’s heart lungs and blood vessels can be seriously damaged with just one worm.  It can cause respiratory distress in a ferret.  Symptoms include, Lethargy  or fatigue and tiredness, Open-mouth and/or rapid breathing, Pale blue or muddy gum color and coughing.  And, of course, death.


Screening is important for Ferrets. but this can be a problem.  Your vet may want to do antigen testing and diagnostic imaging like an echocardiogram to look for worms.

What do I do if my Ferret has heartworm?  The treatment is similar to cats.  Check with your vet as to what can be done and the dosages.  Remember that Ferrets are very small.


“Prevention is the best medicine.”