Understanding Heartworm in Dogs: Causes and Prevention

There’s nothing worse than discovering that your beloved dog is suffering from an illness. And, as far as canine illness goes, heartworm is certainly undesirable. This article will go through the basics of this terrible disease, including the phases that it will cycle through and how it is prevented and treated. By the end, you’ll have a much more comprehensive understanding of this illness and what the dogs who experience it suffer through.

What Is Heartworm Disease in Dogs?

Heartworm in dogs is a serious disease that results in the damage and ultimate failure of many of your dog’s internal organs, including their heart, lungs, and kidneys. This disease is developed through a type of parasite called the Dirofilaria immitis. This parasitic worm is distributed through the bite of a mosquito, where the worms lie dormant until they become infective.

Although it has been reported to occur in all fifty of the United States, it is most prominent along the Atlantic and Gulf coasts. It takes 6-7 months until the worms develop into adults, and once that occurs, the adult heartworms mate and reproduce their children into the dog’s bloodstream. It’s important to note that the disease is not contagious, and can only be spread through mosquitos.

When they become adults, the worms look a bit like spaghetti noodles. They live for 5-7 years, and the females can reach up to a foot in length. The average number of worms living in an infected dog is around 15, but it can be anywhere from 1 to 250.

How to Know When to Get Your Dog Tested for Heartworm

There are a number of factors that can go into when and how frequently you should test for heartworm in dogs. Typically, if your dog is seven months of age or older, you should get them tested before starting any kind of prevention. Even if they look healthy on the outside, that doesn’t mean they aren’t in the beginning phases of infection. Heartworm preventatives don’t kill active worms, so it’s important to check before doing anything of the sort. Annual testing is generally the recommendation. But, have a discussion with your vet about the best method for you and your furry friend.

Symptoms to Look Out For

The symptoms and severity of heartworm in dogs relate to the amount of worms living inside of the dog. This, which is often referred to as ‘worm burden,’ as well as how long the dog has been contaminated determines how bad the illness is. There are phases to how severe the disease is, divided into classes. The higher that the class is, the worse and more intense the presence of the disease becomes.

• Class One: No symptoms, or occasional coughing.
• Class Two: Mild symptoms of coughing, as well as increased tiredness after playing or exercising.
• Class Three: Sickly appearance, persistent coughing, and tiredness even after mild activity. There may also be trouble breathing and signs of heart failure. During this class, the changes in the heart and lungs will be observable on an x-ray.
• Class Four: This class is also called caval syndrome. The worm burden in this class becomes so heavy that blood flow becomes physically blocked by the amount of worms. This is life-threatening, and surgical removal is the only treatment option at this point. Even with surgery, though, dogs at this stage are likely to pass away.

Although not all dogs with heartworm will develop caval syndrome, they will eventually succumb to the disease due to the impact it will eventually have on the rest of their internal organs. It is, of course, best to get the dog treatment at first sign of illness.

Testing For Heartworm in Dogs

The test is fairly simple. A veterinarian will use blood to check for specific proteins, which are called antigens. These tests can, more often than not, accurately predict the presence of one or more adult heartworms. The earliest that it can be detected is roughly five months after it has been bitten by the mosquito that infected it.

There’s another test that detects something called microfilariae. This indicates whether the dog has been infected with adult heartworms, as only mating worms will produce the microfilariae. This test takes a bit longer to be viable, as the worms must be at least six months old before they are of mating age.

Dog Heartworm Treatment

There are two commonly used, FDA-approved treatment drugs for heartworm in dogs. The first is Melarsomine dihydrochloride, which contains arsenic. It is given through a deep injection into the dog’s back muscles. It can treat all three initial classes of the disease. The other common drug is called Advantage Multi for Dogs, which is a topical solution applied to the dog’s skin.

Treatment for this disease is not easy on your dog’s health, and it certainly isn’t easy on your wallet! The very medication that will rid your dog of their heartworm also has the potential to be severely toxic to its body. It could cause life-threatening complications in some instances and requires several visits to the vet. That’s why, as we’ll cover in the next section, the best treatment for this illness is prevention.

Preventing Heartworm in Dogs

There are abundant products to prevent heartworm in dogs. All FDA-approved, they only require a prescription from a licensed veterinarian. Most of these products are given on a monthly basis. They range from topical treatments to oral pills and tablets, both chewable and non. Alternatively, you can get an injection from your veterinarian every six to twelve months. The bonus of these treatments is that, alongside heartworms, the medication can also help prevent other intestinal worms and parasites like fleas and ticks.

According to the American Heartworm Society, there is a simple phrase to help you remember getting your dog tested. This is “Think 12,” which refers to getting your dog tested for heartworm every twelve months! And, of course, providing them with twelve months’ worth of prevention medication every year.