April is Heartworm Awareness Month. How Much Do You Know About Heartworms?

Where there are animals and mosquitoes, there are heartworms. Plain and simple. April is National Heartworm Awareness Month, and if you have pets, heartworm prevention is a must. Did you know that heartworm disease is almost 100% preventable? It’s true. And prevention is much easier and more affordable than trying to cure heartworms.

Understanding the basics of heartworms—how they spread and thrive and how to treat them—will help you appreciate why continuous, year-round, uninterrupted prevention is the key to protecting your dog from this deadly disease. So, in honor of National Heartworm Awareness Month, we’ve collected a few frequently asked questions about heartworms:

Heartworm FAQs:

What are heartworms and how are they spread?

In a nutshell, heartworms are just that—foot-long worms that take up residence in the heart (and lungs) of your beloved dog. Over time, they pose serious health risks to your dog, including heart failure, lung disease, and damage to other organs. While dogs tend to be at the highest risk, heartworms can also infect cats and ferrets, as well as foxes, coyotes, and sea lions.

Dogs are natural hosts for heartworms, who can carry out most of their life-cycle inside of a dog and live there for many years. Unchecked, heartworms can that live by the hundreds in a dog’s heart.

You might say the mosquito is at the “heart” of heartworm disease, it serves at the intermediate host for the parasite. When a mosquito bites an infected dog, fox, or coyote, it picks up microscopic baby worms that have been produced by adult female heartworms living in the host animal. Those baby worms develop in the mosquito into infective larvae over the next 10-14 days and can then be passed along when that mosquito feeds again. After migrating through your pets various tissues for about 6 months and going through several larval stages, the larvae finally become mature adult heartworms, and take up residence in the heart.  There they can live 5-7 years in dogs and 2-3 years in cats. Every mosquito brings a new threat, and can lead to ever-increasing numbers of heartworms in your pet.

What is the ideal age to start prevention?

Even an 8-week-old puppy can begin heartworm prevention, so Ambassador encourages you to get your puppy started at that first puppy visit. It is unlikely that a puppy that young has been infected, but even if she has, the preventative medication will kill any migrating larvae in her body.

If you have an older dog that’s either never been on heartworm prevention or whose prevention has lapsed, or if you’ve recently adopted an adult dog with an unknown heartworm prevention program, start with testing. Heartworm preventative can be dangerous if administered to infected dogs. If Buster checks out, then he’s good to go to start prevention immediately.

Technically heartworm prevention meds don’t protect your dog from an infected mosquito spreading larvae to your dog. But the medicine will kill the very young larvae during that critical initial 14-day window following a bite. If you miss a dose or give it late, those larvae can become “teenagers” and are much harder for the preventative to knock out. So treat your dog every month, and don’t miss a dose.

If keeping track of all this is not your strong suit, use those handy calendar stickers included in heartworm prevention packets to remind you. If even that is not good enough (because you forget to use your calendar! It happens.), there are apps for that!

Are heartworms concentrated in specific geographic regions?

The short answer is: Yes. And No. Of course there are climates and environments where mosquitos are more prevalent. If you’ve ever camped out in the hot Low Country, or say, in the Florida Everglades, you know what we’re talking about. Mosquitos are out in droves. And they can be big.

However, shifts in climate, building practices, and relocation of pets all contribute to the spread of heartworm disease in all fifty states. Variations in climate and presence of infected strays and other wildlife carriers can cause dramatic fluctuations in the rate of infection from year to year, even in the same community.

The safest strategy is to keep your dog on heartworm prevention all year, regardless of where you live or what time of year it is. Dogs can even get heartworm in the winter. The American Heartworm Society calls this the “Think 12” approach: 1.) Test your pet every 12 months for heartworm, and 2.) Use heartworm preventative 12 months a year.

Can I tell if my dog is infected?

Early on, or in mild cases, symptoms may not be obvious. As the disease worsens, or if your dog is older, very active, or has other health problems, signs can be more prevalent. Your dog may have a cough and turn his nose up to his usual daily exercise, displaying signs of fatigue and decreased appetite.

As the disease advances, heart failure and excess fluid in the abdomen are risks. Your dog may appear to have a swollen belly. In severe cases where the heartworms are numerous, blood flow can be cut off from the heart and cause cardiovascular collapse. If your dog is suffering from this stage of heartworms, she may struggle to breathe, show pale gums, and have blood in her urine. At this point intervention is difficult.

If my dog gets heartworms, what should I expect?

Our goal and hope is that you never have to experience this disease with your dog. However, if you do, take comfort in knowing that heartworms are highly treatable in most dogs. We’ll start by confirming the disease in our in-house diagnostics lab.

Before actual treatment begins, it is important to stabilize your dog’s condition. We do this because administering treatment to an infected dog poses a health risk to the dog and can be extremely taxing on your dog’s internal systems. We want to make sure that we give your dog the best chance for full recovery.

Once your dog is stable, Ambassador will establish and begin a treatment protocol. The American Heartworm Society provides guidelines for treatment. In milder cases, treatment is highly successful. In more severe infestations, there can be threat of complications, though success is still very hopeful.

Ambassador Animal Hospital will administer treatments that will kill adult and immature worms as well as controlling and closely monitoring side effects. The duration of this process depends on how advanced the disease is. Typically, infected dogs will require at least two treatments to fully eradicate the heartworms. In most cases, we will keep your dog overnight for at least two days after the each treatment to watch for any adverse reactions.

We’ll test again for heartworms 6 months after treatment to confirm that we have eliminated all worms. And of course, we will get you set up with a life-long heartworm prevention plan.

Is your dog on heartworm prevention? If not, don’t lose another valuable day to protect your four-legged friend from heartworms. Call and make an appointment to bring her in for a heartworm test and to start your prevention regimen right away. If you and your pooch are all set, but you just need more medication, check out our convenient online pharmacy. If you’re on track with prevention, but have questions or would like further information about heartworms, we are here to talk with you.


My husband and I love this place. They always love seeing our cat Mango when we bring him in each month for his medicine and to get his nails... read more

Jason R.

The staff are incredibly friendly and knowledgeable! I've taken both my cats there since they were kittens and they are always so good with... read more

Meetra M.

To my Ambassador family, thank you again for taking such great care of Mauser. You have made going to the vet easy and worry free. Great service... read more

Shelly J.

Jason R.

My husband and I love this place. They always love seeing our cat Mango when we bring him in each month for his medicine and to get his nails trimmed. Today we will taking our new puppy Melon for her first visit. I would highly recommend Ambassador Animal Hospital if you are looking for a great place to take your fur babies. 10/10.

Meetra M.

The staff are incredibly friendly and knowledgeable! I've taken both my cats there since they were kittens and they are always so good with them.

Shelly J.

To my Ambassador family, thank you again for taking such great care of Mauser. You have made going to the vet easy and worry free. Great service starting at the door right into the vet room!! Both vets are amazing they take their time with your pet and explain everything . Front desk is quick and efficient and always friendly to you and your pet!!

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