Heartworm Disease on the Rise: Is Your Dog at Risk?

Heartworm Disease on the Rise:  Is Your Dog at Risk?

As summer is quickly approaching which means sitting in the sun at the beach, going out on a boat at the lake, or going to a delicious BBQ at a friend’s house.  Unfortunately, summer also brings out the INSECTS!  One insect  in particular that I hate is Mosquitoes.  We are all aware of the itchy red bumps on our legs and arms that these pests create.   As a veterinarian, mosquitoes concern me for another reason – THEY TRANSMIT HEARTWORM DISEASE to our dogs and cats.


I am sure that most everyone has heard about heartworms.  The American Heartworm Society (the leading organization in the country that educates the public on heartworm disease) was founded in 1974, which tells you how long we have recognized this potentially life-threatening disease.   If you have taken your fur baby to a veterinarian, I am sure that you have been educated about heartworm disease.   If not or you forgot what was said I will catch you up.  If you are a heartworm expert, you can skip the next paragraph!

Heartworms are foot long internal parasites that affect the heart, lungs and blood vessels.  These parasites can affect just about any animal, though I am going to focus this article more on dogs since they are a natural host (foxes, coyotes, and wolves are also common hosts).  Infected dogs or wild animals carry microfilaria which are the baby stage of the heartworm.   Mosquitoes ingest the microfilaria when an infected animal is bitten.  The microfilaria then develop into larvae inside of the mosquito  in about 14 days.   The larvae are then transmitted during the next mosquito bite to the new host such as our dogs.  These larvae take about 6 months to develop into an adult heartworm.


Obviously heartworms have been around for a long time and there are many great preventives on the market.  So why did my title say that heartworm disease is on the rise?  Many experts believe that we are starting to see resistance against some of the preventives, while others suggest compliance (not keeping our dogs on a heartworm preventive all year round) is the main cause.  At this point, we do not have the exact answer but the number of heartworm positive dogs across the country has been increasing.

At Fox Creek Veterinary Hospital, we have seen EIGHT dogs in the last 6 months that have heartworm disease  (Just to give you a comparison, we normally see on average 1-2 heartworm positive dogs a year).   The American Heartworm Society (AHS) recently released a newsletter in which they reported that there has been a 21.7% increase in heartworm positive dogs in the last 3 years.


I am not writing this to scare anyone (I apologize if I did), and with the recent rain and flooding mosquitoes are going to be terrible. I really just want to let everyone know that it is more important than ever to make sure our beloved four legged family members are on a heartworm preventive.   An annual heartworm test  is also extremely important to make sure your dog is free from adult heartworms.    I am hopeful that when the AHS releases new heartworm data in the future that we will see a decrease in the number of dogs with heartworm disease!


I would love to hear from you if you have any questions regarding heartworm disease or any other questions about your fur babies. I hope to have more entertaining and educational blog entries in the near future. Please come back soon!

~Dr. Matthew Bechtel

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