The silent killer: How heartworm threatens dogs and how to stop it

Heartworms are a dangerous parasitic infection in dogs that if left untreated, can cause organ damage and death. Preventative medications ensure that mosquitos, fleas, and ticks cannot lay eggs on your dog’s body and, thus, infest it.

Heartworms are a severe condition in dogs that could lead to heart failure, lung disease, or damage to other vital organs. In this health condition, foot-long parasitic worms inhabit the dog’s heart, blood vessels, or lungs. As they grow, they disrupt the functioning and may lead to death.

Unfortunately, this condition is not only deadly but also common. Every one out of 100 dogs in the US is likely to suffer from this disease.

In this post, we’ve summed up all facts and actionable tips every dog owner needs to know to safeguard their dog against this fatal health condition. 

How do dogs get heartworms?


First, let’s explore how dogs get heartworms. It all begins with a mosquito bite.

When a mosquito bites an infected dog, cat, fox, ferret, or any other infected animal, it picks up the eggs of the heartworms. After 10-14 days, the eggs picked up by the mosquito develop into larvae within its own body. So, the larvae are transferred into its body when the mosquito then bites another animal.

The larvae travel directly to the heart via the bloodstream, where they infest. The larvae or the infested eggs do not mature until six months. Beyond six months, they mature and reproduce. These worms can live in a dog’s body for up to seven years. And in a cat’s body, they can live up to 2-3 years.

But bear in mind that they multiply rapidly. Therefore, only after six months of infestation is your dog likely to house a colony of the heartworms. In rare cases, the eggs and larvae can also be transferred to humans via a mosquito bite. Hence, heartworms are not only dangerous for your fur buddy but also for you and your family.

Also, it is worth noting that the risk of heartworms is higher in tropical and subtropical areas.

What are the symptoms of heartworms?

The symptoms of heartworm disease may vary depending on the severity of the infection. In the early stages, dogs may exhibit minimal or no signs. And this is why heartworm disease is also known as a silent killer. It’s challenging to detect the presence of heartworms.

However, as the infection progresses, you’ll witness some prominent indicators, such as the following:


If your dog persistently coughs, especially during or after an exercise session, you should take immediate notice. It is a common symptom of heartworm disease. The worms’ presence in the lungs and airways causes irritation and inflammation, which leads to coughing spells.

Fatigue and exercise intolerance

Infected dogs may experience reduced energy levels and tire more easily during physical activities. It’s because of excessive strain on their cardiovascular system.

Weight loss

Unexplained weight loss can occur as heartworms disrupt the dog’s normal metabolic processes, interfering with nutrient absorption.

Difficulty breathing

As the infection worsens, dogs may experience difficulty in breathing. They may even have visibly rapid or difficult breathing, indicating respiratory distress.

Swollen belly

In some cases, heartworms can cause fluid accumulation in the abdomen. You can witness a swollen or distended belly.

Bulging ribs

Heartworms can also cause fluid accumulation in the lungs, which may lead to bulging ribs in some dogs.

Heartworms can infect dogs, cats, and other animals. They are transmitted via mosquito bites, and can live in the host animal’s body for up to seven years.

How to treat heartworms?

Although heartworms are life-threatening, timely treatment can save your dog effortlessly. So, as soon as you observe even one of the symptoms mentioned above, rush your dog to the vet immediately.

Now, the severity of the infection, the overall health of the dog, and the presence of any additional medical conditions are some factors considered when determining the most suitable treatment plan. So, the same treatment for each dog varies.

But here’s a general veterinary course of action that you can expect:

  • Diagnostic testing: Veterinarians conduct a series of diagnostic tests to confirm the presence of heartworms. These may include blood tests and imaging techniques such as X-rays and ultrasounds.
  • Stabilization: Dogs with severe infections may need stabilization to manage symptoms and improve their overall health before commencing treatment. This may involve medications to reduce inflammation and control respiratory distress.
  • Adulticide treatment: The primary aim is to eliminate adult heartworms in the dog’s heart and blood vessels. This is typically achieved through administering adulticide medications that target the worms directly.
  • Rest and restricted Activity: After the adulticide treatment, dogs are often required to undergo a period of rest and restricted activity to facilitate healing and reduce the risk of complications.
  • Preventive medication: Once the dog has completed heartworm treatment, preventive medications are crucial to prevent re-infection. These medications are administered monthly and act as a safeguard against future heart.

Tips to prevent heartworms

As evident as it is, heartworms are not a positive experience for both dogs and dog owners. So, doing your best to avoid this health condition altogether is highly advisable.

Here are a few tips to help you prevent heartworms in your doggo:

  • Regular vet visits: Take your dog for at least twice-yearly health checkups. Make sure you mention all behavior or diet changes.
  • Administer preventative medications: Give FDA-approved preventive medicines to your dog, like NexGard for dogs 10-24 lbs. These medications ensure that mosquitos, fleas, and ticks cannot lay eggs on your dog’s body and, thus, infest it.
  • Minimize mosquito exposure: Reduce your dog’s exposure to mosquitoes by avoiding outdoor activities during peak mosquito hours. Use mosquito repellents specifically formulated for dogs and ensure proper screens or mosquito nets are in place.
  • Environmental control: Mosquitoes breed in standing water, eliminating potential breeding grounds. Empty or treat stagnant water sources around your home. This can significantly reduce the local mosquito population.
  • Educate yourself: Stay informed about heartworm disease, its transmission, and preventive measures. By understanding the risks, you can proactively safeguard your dog’s health.

Final words on heartworms

By now, we hope you’re aware of how seriously threatening the heartworms can be for our canine friends.

If and when you notice even the slightest of all symptoms, rush to your vet immediately. Do not wait for the symptoms to get stronger, so you can be sure.

This could mean greater infestation and reduced chances of successful recovery.

Arslan Hassan is an electrical engineer passionate about writing, designing, and anything tech-related. His educational background in the technical field has given him the edge to write on many topics. He occasionally writes blog articles for Dynamologic Solutions.

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