Part 1: What is a Heartworm?

Aug 17, 2018 by Dr Katie McConnell

Part 1: What is a Heartworm?
          In this 3 part series, I am going to tackle the topic of Heartworms.  There are many aspects of the organism to discuss such as transmission, symptoms, treatment, and prevention to name a few.  I will try to touch briefly on the most important features of Heartworm Disease.  So, stay tuned to Tchefuncte Animal Hospital if you are interested in knowing a little more.  

          What is a heartworm you might ask? Heartworms, or Dirofilaria immitis, are a type of worm that can live in the heart, lungs, and related blood vessels of dogs, cats, ferrets and many other wild species.  Not trying to scare you on this, but Dirofilaria immitis infection has even been reported in humans as well.  Heartworms have been diagnosed in all 50 states of the US and around the globe.  It is considered at least regionally endemic in 48 of the US states. As you can imagine with foot long worms living in your heart, they can cause a serious and life-threatening condition called Heartworm Disease.  

          Heartworm Disease has many stages (ie 1-4) increasing in severity of clinical signs, or symptoms.  The most common stage, or Class, is the first in which the pet is free of symptoms and appears to be perfectly healthy.  The second Class is characterized by mild to moderate signs including cough or increase in tiredness of the pet. This stage progresses to Class three which is when the pet begins to show worrying symptoms, such as exercise intolerance, severe cough, decrease in appetite with weight loss, and heart failure.  Class four is described as Caval Syndrome. At this point, you may see labored breathing, pale gums, and blood tinged urine in addition to the previous mentioned signs. Once in the final stages, it is difficult and can be fatal to treat Heartworm Disease. Our main goal when discussing the disease is to impress a sense of important on prevention.  Understanding prevention of Heartworm Disease means understanding the life cycle, OR trusting in you veterinarian completely. Whichever you prefer.

          The life cycle of a heartworm is long and somewhat complex.  The lifecycle is so important for us to understand because it dictates our methods of intervention, treatment, and prevention.  The vector, or transmitter, of heartworms is the mosquito. If you consider the population of mosquitoes in Louisiana, I don’t need to tell you why we are one of the states with the highest incidence of heartworm infection.  The mosquito bites an infected dog (or cat) and picks up microfilaria, or baby heartworms, from the blood they ingest. The microfilaria go through the “mosquito phase” over 10-14 days to develop into larva. Then the mosquito bites another dog (or cat) and infects them with the larva.  The larva, or more developed baby heartworm, develop into an adult in approximately 2 months, give or take a few weeks. This adult then spends 4-5 months developing into a mature heartworm that can produce microfilaria. And the whole thing starts over again with another mosquito that bites the infected dog (or cat).  Phew!

          The important things to know here are… A) Heartworms are spread by mosquitoes. B) The life cycle is long and complex, meaning it takes 6-7 months from bite to positive heartworm test. C) Prevention is targeted at select stages with a small window of protection. This is why Drs Moores, Ferrara, and McConnell recommend your pets be on prevention year-round.  Year round heartworm prevention ensures proper coverage against heartworm infection. At your next wellness appointment in Madisonville,  ask your veterinarian about which prevention would be best for your fur baby. We can tailor a plan for your needs.

Stay tuned for the next installment of our 3 part series on Heartworms.  And if you have any questions or concerns, call us at 985-845-7484! 

Appointments & Reservations

Our veterinarians, Drs. David Moores, Laura Ferrara, and Adam Brown are now accepting new patients. Bring your dogs, cats, reptiles, pocket pets, and rabbits to Tchefuncte Animal Hospital for veterinary care in Madisonville. 

Contact our office at 985-845-7484 today to schedule an appointment or for more information.

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