Common Myths about Heartworm Disease

Heartworm disease can be a very serious and potentially lethal illness, but there is a great deal of misinformation floating around about how the disease is transmitted and prevented. Is it really necessary to give heartworm prevention in the winter? What if my pet rarely ventures outside? In order to dispel some of the common misconceptions, let’s explore some heartworm myths and facts.

Myth #1: Indoor Pets are safe from heartworm.

While some dogs may only go outside for a quick bathroom break or walk around the block, there is still potential to contract heartworm disease. Heartworm in transmitted through the bite of a mosquito carrying heartworm larvae, so even indoor pets can be infected if mosquitos get inside the home or the pet is outside for any length of time.

Myth #2: Cats don’t get heartworm.

While dogs are more commonly infected with heartworm, cats are susceptible to the disease, too. Indoor cats have been known to become infected, and unlike dogs, there is no approved treatment for cats. Monthly preventatives are the best way to ensure that your cat is protected from potentially fatal heartworm infection.

Whether indoors or outside, it only takes one bite from an infected mosquito to transmit heartworm. And yes, cats can get heartworm, too!

Myth #3: My dog would be showing symptoms if they had heartworm disease.

There are typically no symptoms during the early stages of heartworm infection. After being bitten by an infected mosquito, it takes about 6-8 months for the heartworm larvae that is injected into your pet’s bloodstream to develop into a form that is detectable by standard blood tests. By the time that symptoms such as cough, fatigue, and weight loss occur, the disease is likely in advanced stages. This is why annual testing and early detection is critical.

Veterinary Assistant, Allison, preforms a routine heartworm test at the SPCA Tampa Bay Veterinary Center. A simple heartworm test can be performed in about ten minutes, and should be done annually. 

Myth #4: Heartworm is not present in my area.

Heartworm disease has been diagnosed in all 50 states. While the prevalence can vary from one geographic location to another, there is potential to contract the disease anywhere. Some areas that had historically low levels of heartworm disease have seen increases in cases due to factors such as increasing temperatures and the transferring of infected dogs from one region to another. 

Image from the American Heartworm Society showing the increased prevalence of heartworm disease by geographic region over time. 

Myth #5: I don’t need to give heartworm prevention in the winter since there aren’t any/as many mosquitos.

It is important to give heartworm prevention year-round for several reasons. Once you stop giving heartworm preventatives, your pet is no longer protected from infection. If you then resume giving prevention without testing first and there are heartworm larvae (microfilaria) present in the bloodstream, the medication can kill the microfilaria so quickly that it can send the pet into shock and cause death. Since we cannot predict when the last mosquito will be out or the first will emerge each season in, year-round prevention is important in all climates. Here in Florida, mosquitos are ubiquitous year round so the danger is even greater.

Myth #6: There is a treatment for heartworm so it is not a big deal.

Heartworm treatment is a long process that can be very hard on your pet’s body. In some cases, pets will succumb to the disease or suffer lasting health concerns even with treatment. It can also be financially prohibitive for many families to pay for heartworm treatment. The cost of monthly preventatives may seem high to some, but it is a drop in the bucket in comparison to cost of treating heartworm disease.

Being able to decipher fact from fiction regarding heartworm disease allows you to provide the best protection for your pet. Even with year-round prevention, annual testing is a critical component of keeping your pet safe since even the most effective medications are not 100% successful in preventing disease. Be sure to speak with your vet to determine the best routine to keep your pet heartworm free. For more information on heartworm disease, visit the American Heartworm Society.

Visit our website for further information on services offered by SPCA Tampa Bay Veterinary Center, or to schedule an appointment call 727-220-1770. 


Blog crafted by Amanda Corzatt, former shark trainer, goat wrangler, and serpent spokesperson, turned Digital Marketing Creator at SPCA Tampa Bay