Heartworm Disease

Heartworms are worms that spread through a pet’s bloodstream and live in the heart chambers. Heartworms usually infect dogs, but cats can also get heartworms. Dogs get infected by mosquitos. Humans can't get heartworms. Heartworms are a serious disease, and they can shorten your pet's life.


When heartworms infect a pet, they can block the flow of blood through the heart. The worms also irritate and damage the heart lining. With enough time, the heart damage can kill a pet. Sadly, heartworms are very common in Georgia, as you can see in the map below. The red areas are those with the most cases of heartworm.


Heartworms can be easy to miss. Your pet may get tired easily and want to play or walk less. Your pet might cough, have trouble breathing, or lose weight. Sometimes, though, your pet will look and act normal before the worms multiply.



There’s good news, though. With a monthly medicine, you can prevent heartworms in your dog or cat. Good prevention medicines for dogs include Heartguard, Interceptor, and Comfortis. Cats can have these medicines or another medicine, Revolution. Some of these medicines are given by mouth each month. Others go on the pet’s skin. By Georgia state law, your pet must be tested for heartworms before receiving these medicines, because they can make an infected dog very sick.



If your pet already has heartworms, your vet will need to give two medicines: doxycycline and Immiticide (aka melarsomine).Sometimes a vet will surgically remove worms to help your pet feel better. If your pet has problems from the disease, your vet may prescribe more medicines to help.



Some people support “slow kill,” which means giving a preventative every month for two years. We do not recommend slow kill because the worms continue to damage the pet’s heart. Also, slow kill may cause drug resistant parasites.


This is the heartworm’s life cycle. Microfilariae is another name for young heartworms.




Additional Resources


**Warning** some of these sites contain graphic images of heartworm infestations.


The American Heartworm Society: Resources for Pet Owners


Web MD: Heartworm Facts and Myths


FDA: Facts About Heartworm disease