Heartworm Disease in Dogs: The Top 10 Myths that Dr. Buzby Doesn’t Believe (And Neither Should You)

Our dogs are counting on us to know the facts about heartworm disease.

There are many myths and misconceptions about heartworm disease in dogs. And social media platforms help fan the flames of misunderstanding. As an integrative veterinarian, I have comforted grieving clients who have lost their dogs to this preventable disease and I have read recent information about the growing use of home remedies in place of FDA-approved heartworm preventative. That’s why I want to help you help your dog by sharing the facts about heartworm disease. If you have concerns about heartworm disease in dogs, let’s bust these myths together.

MYTH #1:  Heartworms do not exist. Veterinarians and drug companies made them up.

A heartworm picture is worth a 1000 words. These heartworm pictures of a dog’s heart and lungs post-mortem aren’t easy to look at, but they clearly show that heartworms exist. You can see the mass of heartworms in and around the dog’s heart. These are foot long heartworms that lived in the heart, the lungs, and the associated blood vessels. Left untreated, heartworms can live from five to seven years in dogs. And dogs can get several hundred worms in that amount of time.

MYTH #2:  I don’t need to give a heartworm preventative to my dog during the winter months because it’s cold outside.

Cold temperatures do not safeguard dogs from heartworm disease and the insects that carry it. I’ve seen many sad cases of dogs who have tested positive for heartworms. The dogs’ owners stopped giving preventative during the cooler half of the year—the winter months. Some species of mosquitoes are adapting to colder climates. Heartworm disease exists year-round in the host animal—such as a coyote, fox, wolf, or an infected dog. It is really important to give heartworm preventative year around. The American Heartworm Society has a slogan:

THINK 12. Protect your pet from heartworm 12 months a year. Test for heartworm every 12 months.Click To Tweet

Please help spread the word.

MYTH #3:  We don’t have heartworm disease in our state.

This is a very common misconception. All 50 states (and worldwide) have documented cases of heartworm disease in dogs.  Not only has it been recorded, but it is also on the rise. Here is a true story that illustrates why this is the case: A client came to me with a dog that needed to be treated for heartworm. The dog and owner had moved into the area about three years prior. Not only was I sad for the dog, but I was also sad because that dog, during those three years, had served as a “reservoir of infection” for the area. That means that if a mosquito bit the infected dog, then that mosquito would then become infected and potentially infect other dogs. It is a domino effect.

Secondly, the convenience and ease of travel in today’s world fans the spread of heartworm disease. After hurricane Katrina, for example, over a quarter of a million pets, many of whom were heartworm positive, were shipped around the country in this great concerted rescue effort. As encouraging and uplifting as this was, it also guaranteed the increase of heartworm incidents around the country.

MYTH #4:  My dog is an indoor dog so I don’t need to give a heartworm preventative.

Unfortunately, mosquitoes know no man-made boundaries. Whether it is a house or a fenced in yard, mosquitoes can fly and they’re also blown by the winds, so certainly, they can travel the country. They can get indoors and bite unprotected dogs inside the house. Even an indoor dog who rarely goes outside for more than a walk or potty break is still at risk for heartworms. There are up to 30 different species of mosquitoes that transmit heartworms and they can all slip into a house quite easily.

MYTH #5: My dog’s fecal test is negative so heartworm testing is not necessary.

Many other species of worms (hookworms, roundworms, and tapeworms, for example) are internal parasites that live in the intestines, in the gastrointestinal tract. Heartworms live in the circulatory system—the lungs, the heart, and the associated blood vessels. And because they are found in the heart and the circulatory system (not the intestine), a blood test is needed to detect their presence. Veterinarians administer a separate test (not a fecal test) where they draw a few drops of blood from the dog. Often the lab test results are available in just 10 minutes.

MYTH #6:  A home remedy will protect a dog from heartworm disease.

Essential oils. Lemon juice. Vinegar. Coconut oil. There is no home remedy that a dog owner can mix in any form that will prevent a dog from getting heartworms. While I have a healthy respect for some home remedies when used appropriately (and certainly, it is very important that you use the right ones with caution and wisdom), they are not an appropriate treatment for heartworm disease. (And since I’ve mentioned essential oils, if they are in your consideration set for your dog in any way, it is crucial to do your research. Certain brands of essential oils are dangerous for dogs. There are a few that are safe, but they need to be used judiciously. In all cases, they are not an appropriate treatment for heartworm disease.) Please administer FDA-approved heartworm preventative monthly for your dog.

MYTH #7:  A dog’s thick fur will protect him or her from heartworms.

“My dog has a really thick coat. There’s no way the mosquito can bite through it.” It is a common misconception that a dog’s thick fur protects him or her from getting heartworm disease. The truth is that mosquitoes bite pets where the hair is thinnest. Often the hair, even in a thick-coated dog, is still thin on the legs or the belly. And that’s where the mosquito is going to bite. I have personally treated heartworm positive Pomeranians, huskies, and other breeds that are known for their thick undercoats. It’s not a protection. Mosquitoes will find the dog’s soft inner groin, belly, and skin where the coat is thinnest.

MYTH #8:  Heartworm pills are toxic to dogs.

I understand the concern about what we are putting into our bodies and our dogs’ bodies. But I always tell my clients that with everything in life we have to weigh the benefits versus the risks. I will go on record here that there are certainly many safe FDA heartworm preventatives on the market. I personally give my dogs Heart Guard Plus. It has been around for a long time. And there are other good heartworm preventatives available.  My dogs get a monthly heartworm preventative and I’d never open them up for the risk of contracting heartworm disease.

MYTH #9:  My dog’s on a flea and tick preventative, so heartworms are covered.

Currently, there is no universal medication for flea, tick, and heartworm prevention in the United States. If you live in the U.S. and you are giving your dog a flea and tick preventative and you believe it prevents heartworms, please speak with your veterinarian. Make sure you are giving your dog monthly heartworm preventative faithfully. There’s no room for error, so if you have questions, I encourage you to have a conversation with your vet.

 

MYTH #10:   It’s ok to go without a heartworm preventative. I’ll treat the dog if he ever gets heartworms.

Treatment for heartworms is both expensive for the dog owner and very painful for a dog. An arsenic-based injection is used to treat heartworm disease in dogs. It is not benign stuff. This is a hardcore treatment for a canine companion. It has to be injected deep in the dog’s muscle. This is painful. The dog must be confined and kept quiet because, as the worms die, they could cause clots in the bloodstream—a life-threatening issue. To help mitigate this risk, the dog is kept very still for months during the course of treatment. (Obviously, this is a challenge in and of itself.) Finally, treating a dog who has heartworms is expensive. Typically, treatment is done through multiple injections. Also, additional medications and diagnostic tests are needed as the heartworm disease can cause other permanent changes in the dog’s body. These changes are irreversible and impact the dog’s quality of life.

Let’s bust these myths together. 

If you see these myths about heartworm disease in dogs being propagated in social media, please help set the record straight. Ultimately, dogs are the ones who suffer when we get this wrong. The benefits of a heartworm preventative outweigh the risks. If you are interested in more information, I encourage you to check out my companion podcast episode, 10 Heartbreaking Heartworm Myths, or visit the American Heartworm Society’s website.

What questions or concerns do you have about heartworm disease in dogs? Please comment below.