Heartworm Disease: What It Is & How to Prevent It

February 23, 2023

Ticks and fleas are some of the most common pet parasites, but there’s another parasite that dog parents need to know about: heartworm. Left untreated, it can make your pups very unwell and can even lead to death, but by knowing the signs of heartworms in dogs, as well as ways to prevent it, you can make sure your dog lives a happy and healthy tail-wagging life. 

What Is Heartworm?

Heartworm, also known as Dirofilaria immitis, is a type of parasitic worm. They’re spread by infected mosquitoes that bite animals, and occasionally people. However, canines, foxes, wolves, and coyotes are the most infected animals. 

Once an infected mosquito has bitten an animal or person, the heartworm enters the bloodstream. Heartworms travel to the lungs and heart — hence the name — and can cause serious harm, including lung disease, heart failure, and organ damage. Adult heartworms can live up to seven years and reach a full length of roughly 12 inches.

What Does Heartworm Disease Do to Dogs?

Heartworm disease can result in multiple symptoms, depending on how many worms are in the dog, how long the infection has been present, and how the dog is coping overall. Typically, pups that have been infected for a long period of time show the greatest number of symptoms. 

It’s important to remember that heartworm disease can affect dogs in different ways. The most common signs of heartworm in dogs include:

  • A persistent cough
  • Lack of energy
  • Tiredness
  • Weight loss
  • Changes in appetite
  • Difficulty breathing
  • Fainting or collapsing 
  • Distended belly
  • Increased urination or drinking

Unfortunately, these symptoms can easily be confused with other ailments and there isn’t a tell-tale sign that your dog has been infected with heartworm. For this reason, it’s important that your pup is treated to regular check-ups with a trusted veterinarian.

How Do Dogs Get Heartworms?

Heartworm disease is spread solely through mosquito bites. It’s not contagious and cannot be passed from dog to dog, or dog to human. After an infected mosquito bites an animal, the larvae develop into adult heartworms — living in a dog’s heart, mating, and reproducing. The offspring, which are called microfilariae, then live in the dog’s bloodstream. If another uninfected mosquito bites that dog, the mosquito will then become infected with the microfilariae, and it starts the whole infectious process again. 

The heartworm larvae take up to seven months to become fully developed and can live in a dog’s system for as long as seven years. Adult heartworms have a similar appearance to cooked spaghetti, and female heartworms, in particular, can grow up to 12 inches in length. A dog can have more than one heartworm, and the number of heartworms in a system is known as the worm burden. The average number of heartworms found in dogs is 15, but in some severe cases, as many as 250 heartworms have been found. 

How to Prevent Heartworm in Dogs

The best way to protect your dogs against parasites like heartworm is to prevent them from being infected in the first place. While heartworm disease can be serious, you can rest easy knowing that you’re doing the best for your pup by following a few simple steps as shown below.

Preventative Medicine 

Your vet can advise on your dog’s risk and recommend the best course of action to suit your needs and budget. There are various types of medicine available that will not only ward off infections but also kill any heartworm larvae. Some pet owners choose a monthly chewable, while others opt for a vaccine that covers pups for up to 12 months. There’s also a type of topical cream available that is spread on your dog’s back. 

A white little dog being fed a treat by its owner.

Regular Vet Visits

As mentioned above, it’s not always easy to tell whether your dog has been infected. The heartworm larvae live in your pup for up to seven months before becoming an adult heartworm. For this reason, annual vet visits are important to help you stay on top of your pet’s health. Not only will a professional vet check for the signs and symptoms of a heartworm infection but also any other parasites that you might have missed. 

A relaxed-looking Husky at the vet.

What to Do If Your Dog Gets Heartworm

No one wants to hear that their furbaby has heartworm, but if it occurs, there are effective treatments available. The first step is to get a diagnosis from a veterinarian. An antigen blood test looks for certain heartworm proteins in a dog’s body. Your vet will also likely use another blood test to determine whether there are microfilariae in your dog’s system. Both tests can show positive results around five to seven months after a dog has been bitten by an infected mosquito. 

Next, your dog’s condition and disease need to be stabilized with restricted exercise and a quality diet. Physical activity can increase the speed at which the heartworm causes damage. Once your dog is stable, a vet can administer treatment. 

The most common type of heartworm disease treatment is a drug administered by an injection, which works to kill any adult heartworms present in your dog’s system. Your vet will determine how many injections your dog needs, depending on their condition. Your pup will then need to be retested six months later to determine whether the treatment worked. 

Take Care of Your Pup

Heartworm disease should be taken very seriously. It can be detrimental to a dog's health when left untreated, not to mention expensive to manage. Taking steps to prevent heartworm in dogs is the best way to make sure your best fur friend maintains a happy and healthy life.

Regular grooming sessions are another great way to take care of your pup. The professional grooming experts at Barkbus have been helping pet parents pamper their dogs and keep their coats fresh and healthy for years. Get in touch with our team today and give your four-legged companion the “spaw” day they deserve.


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