Heartworm Treatment for Dogs

❤️ HEARTWORM TREATMENT FOR DOGS

A positive heartworm test does NOT mean your dog cannot be treated.

Heartworm disease is a serious but treatable disease.

⭐ THERE ARE TWO MAIN TREATMENT APPROACHES

Your veterinarian will determine which option is safest and most appropriate for your dog.

⭐ Our Goal

Our goal is not simply to kill the heartworms.

Our goal is to eliminate the heartworms while minimizing damage to your dog's heart and lungs.

Regardless of the treatment approach, doxycycline and appropriate heartworm prevention are important parts of heartworm management.

💊 Why is Doxycycline Used?

Heartworms naturally carry a bacteria called Wolbachia.

Wolbachia contributes to the heartworm's survival and also plays a role in the inflammation that can occur when heartworms die.

Doxycycline helps by:

• Reducing the amount of Wolbachia inside the heartworms
• Weakening the heartworms
• Helping reduce the inflammatory response when the worms die

Doxycycline is generally given for 4 weeks in newly diagnosed heartworm-positive dogs.

Your veterinarian will determine the appropriate dose and timing.

🥇 FAST-KILL TREATMENT

MELARSOMINE (IMITICIDE®)

Melarsomine is the preferred treatment for killing adult heartworms.

It directly kills adult heartworms over a relatively short period of time.

💉 How does it work?

Treatment consists of 3 injections:

1️⃣ First injection—kills a portion of the adult heartworms.

2️⃣ About 1 month later—two additional injections are given 24 hours apart. These injections eliminate the remaining adult heartworms.

⚠️ Strict exercise restriction is essential throughout treatment and for approximately 6–8 weeks after the final injection.

This is because heartworms can continue to die after treatment, increasing the risk of complications.

🩺 Before Melarsomine Treatment

Before starting treatment, we highly recommend evaluating your dog's overall health and the severity of the heartworm disease.

The recommended testing can help identify possible complications and provide a baseline for comparison if complications develop during treatment.

We recommend:

• 🩸 Blood work ± urinalysis
  • Helps evaluate your dog's overall health and identify underlying problems that may affect treatment.
• 🩻 Chest X-rays—Can help evaluate:
  • Changes in the lungs
  • Changes in the pulmonary blood vessels
  • The severity of the heartworm disease
  • Your dog's risk for complications
• ❤️ Echocardiogram—When necessary
  • Provides additional information about the heart, heartworms, and blood flow through the heart and lungs.
• 🩺 Additional testing or treatment—when needed
  • Depending on your dog's health and the severity of the disease.

⭐ The goal is to make sure your dog is stable enough to begin treatment, identify any problems that may need to be addressed first, and establish a baseline for monitoring your dog's response to treatment.

🐌 SLOWER-KILL TREATMENT

MOXIDECTIN + DOXYCYCLINE

For some dogs, a slower approach may be considered when melarsomine treatment is not possible or is not the best option.

The combination of moxidectin + doxycycline has been studied and can produce a substantial reduction in the adult heartworm burden.

In one important study using topical moxidectin (Advantage Multi®) together with doxycycline, approximately 96% of the heartworms were killed. The reduction in worm burden was similar to what has been reported with melarsomine.

⚠️ The important difference is how fast the worms die:

• Melarsomine ➡️ Kills adult heartworms much more rapidly.
• Moxidectin + Doxycycline ➡️ Kills adult heartworms gradually.

Most of the worms die over approximately 3–6 months, followed by additional time before the heartworm test becomes negative.

⭐ Important

When it can be safely performed, fast-kill treatment with melarsomine remains the preferred option.

However, an appropriate moxidectin + doxycycline protocol can achieve a substantial reduction in adult heartworm burden.

⭐ WHICH MOXIDECTIN PRODUCTS HAVE BEEN STUDIED?

💉 Proheart12®

ProHeart 12 contains moxidectin and has been studied in combination with doxycycline.

In one study: 18 out of 20 dogs were heartworm-antigen negative after one year.

The remaining dogs became negative later.

💧 Advantage Multi®

This is the best-studied product for the moxidectin + doxycycline approach.

The study demonstrating approximately 96% worm reduction used topical moxidectin (Advantage Multi®) together with doxycycline.

💊 Simparica trio®

Simparica Trio contains moxidectin and may be considered in some situations.

However, the evidence specifically supporting its use as part of a moxidectin + doxycycline adult heartworm treatment protocol is less established than the evidence for Advantage Multi.

🦟 HEARTWORM PREVENTION IS STILL ESSENTIAL

A heartworm-positive dog should remain on appropriate heartworm prevention.

Why?

Heartworm prevention helps prevent new infections while the existing heartworms are being treated.

⭐ Heartworm prevention should be given year-round.

Treatment eliminates existing worms, but prevention protects your dog from becoming infected again.

🏃 EXERCISE RESTRICTION

Exercise restriction is one of the most important parts of heartworm treatment.

When heartworms die, they can cause inflammation and may block blood vessels in the lungs.

Exercise increases blood flow through the lungs, which can increase the risk of serious complications while the heartworms are dying.

⚠️ Your dog should avoid:

• ❌ Running
• ❌ Chasing
• ❌ Jumping
• ❌ Swimming
• ❌ Intense play
• ❌ Any strenuous activity

Even if your dog feels good, it is important to follow the exercise restrictions recommended by your veterinarian.

🥇 With Melarsomine

Strict exercise restriction is required throughout treatment and for approximately 6–8 weeks after the final injection.

Heartworms can continue to die after treatment, so the risk of complications does not end immediately after the last injection.

🐌 With Moxidectin + Doxycycline

Exercise restriction may need to continue for approximately 6 months.

This is because the adult heartworms die gradually, and complications can occur while the worms are breaking down.

⭐ Remember:

Keeping your dog calm and restricting exercise can be just as important as the medication itself.

Following these restrictions helps give your dog the safest possible recovery.

⭐ LEARN MORE

The American Heartworm Society provides detailed information about heartworm disease, treatment recommendations, prevention, and a heartworm treatment calculator/treatment-planning tool. Their guidelines are periodically updated based on current research and expert review.

🌐 American Heartworm Society — Heartworm Guidelines

🌐 American Heartworm Society — Heartworm Treatment Calculator & Treatment Plan

❤️ THE TAKEAWAY

A positive heartworm test can be scary, but heartworm disease can be treated.

The goal is to eliminate the heartworms while protecting your dog's heart and lungs from further damage.

Early treatment + strict exercise restriction + year-round prevention = the best chance for a safe recovery.

Your veterinarian will determine the treatment plan that is safest and most appropriate for your dog.

❓HAVE MORE QUESTIONS?

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If you have questions or concerns about your pet, please don’t hesitate to reach out. We’re happy to help. 🐾