Heartworm Disease in Dogs: Causes, Symptoms, Prevention & Treatment Guide
What Every Dog Owner Should Know About Heartworm Disease

Heartworm disease is a serious and potentially fatal condition that affects dogs worldwide. Caused by a parasitic worm, this disease is transmitted through mosquito bites and can lead to severe lung and heart complications if left untreated. As a responsible pet parent, understanding how to prevent, recognize, and treat heartworm disease is essential for your dog’s long-term health.
In this detailed guide, we’ll explore what heartworm disease is, how it spreads, common symptoms, and the best ways to protect your furry friend.
What Is Heartworm Disease in Dogs?
Heartworm disease is caused by a parasitic worm known as Dirofilaria immitis. These worms are transmitted through mosquito bites and primarily target dogs, although they can also infect cats and other mammals.
Once the larvae enter a dog’s bloodstream, they travel to the heart, lungs, and blood vessels, where they mature and reproduce. Over time, these adult heartworms can cause severe damage to the heart and respiratory system.
How Do Dogs Get Heartworms?
The primary cause of heartworm infection is the bite of an infected mosquito. Here’s how the transmission cycle works:
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A mosquito bites an infected animal and picks up microscopic heartworm larvae.
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These larvae develop into the infective stage over 10–14 days inside the mosquito.
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The infected mosquito bites a healthy dog and transfers the larvae.
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Inside the dog, the larvae mature into adult worms over 6–7 months and start reproducing.
Because mosquitoes are the sole carriers, dogs living in mosquito-prone areas are at a higher risk of infection.
Symptoms of Heartworm Disease in Dogs
Early stages of heartworm disease often present no visible symptoms, making regular check-ups critical. As the disease progresses, dogs may show the following signs:
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Persistent coughing
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Lethargy or fatigue
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Difficulty breathing
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Intolerance to exercise
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Weight loss
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Decreased appetite
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Swollen abdomen (due to fluid build-up)
The severity of symptoms depends on the number of worms present and the duration of infection. Some dogs may also develop complications such as heart failure if not treated promptly.
How to Prevent Heartworm Disease in Dogs
Prevention is far easier, safer, and less expensive than treatment. Here are the top heartworm prevention strategies every dog owner should follow
1. Administer Monthly Heartworm Preventives
Veterinarian-prescribed oral or injectable preventives are the most effective way to protect your dog. These medications eliminate heartworm larvae before they mature into adult worms.
💡 Pro Tip: Never skip a monthly dose, as even one missed treatment can leave your dog vulnerable.
2. Reduce Mosquito Exposure
Limit your dog’s exposure to mosquitoes with these simple tips:
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Avoid outdoor walks at dawn and dusk (peak mosquito activity)
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Use dog-safe mosquito repellents
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Install window screens and keep your yard clean and dry
3. Schedule Annual Veterinary Check-ups
Even if your dog is on a preventive plan, annual heartworm tests are essential. Early detection can significantly improve treatment outcomes.
Heartworm Disease Treatment for Dogs
If your dog is diagnosed with heartworm disease, don’t panic—effective treatment is available. However, it’s a multi-step process that should always be supervised by a veterinarian.
1. Diagnostic Testing and Pre-Treatment Medications
Before starting treatment, your vet will perform blood tests, X-rays, and other diagnostics to assess the severity. Medications may be prescribed to reduce inflammation and prepare the body for adult worm removal.
2. Immiticide Injections
The primary treatment involves Immiticide injections, which kill adult heartworms. Depending on the case, dogs may require one to three doses spaced over a month or more.
3. Strict Rest and Recovery
Physical activity can worsen complications. During treatment and recovery, your dog must rest strictly to reduce the risk of heart or lung damage.
4. Post-Treatment Prevention
After successful treatment, your vet will continue your dog on monthly preventives to protect against future infections.
Conclusion: Protect Your Dog from Heartworm Disease
Heartworm disease is a preventable but dangerous condition that all dog owners should take seriously. By understanding how the disease spreads, recognizing the symptoms early, and sticking to a strict prevention routine, you can safeguard your furry friend’s health.
Your dog depends on you for protection. Stay proactive, and consult your veterinarian regularly to keep heartworms at bay.
Schedule Your Pet’s Consultation Today!
Contact Urban Pawz Animal Clinic to schedule your pet’s consultation. Our team is ready to help your pet recover and thrive with our professional, community-centered approach to veterinary care.