What to Do When Your Dog Has Heartworm Disease: Treatment and Management

Heartworm disease, a serious parasitic condition affecting dogs, is transmitted through mosquito bites. The Dirofilaria immitis parasite, once inside the dog, matures and resides primarily in the heart and pulmonary arteries, causing significant damage over time. Understanding the disease, its symptoms, diagnosis, and treatment is crucial for safeguarding your canine companion’s health.

Understanding Canine Heartworm Disease

Canine heartworm disease is caused by the filarial nematode Dirofilaria immitis. After a mosquito ingests microfilariae (larval heartworms) from an infected dog, the larvae develop within the mosquito. When the infected mosquito bites a dog, the infective larvae are injected into the bloodstream. These larvae then migrate to the lungs, where they mature into adult worms over a period of 5 to 7 months. Adult heartworms can live for 5-7 years and reach lengths of up to 12 inches in females and slightly less in males. They reside primarily in the right ventricle and pulmonary arteries, but can occasionally be found in other parts of the body.

Recognizing the Symptoms

The symptoms of heartworm disease often manifest gradually, making early detection challenging. Early signs can be subtle and easily overlooked, including mild lethargy, a persistent, dry cough, or a slight decrease in exercise tolerance. As the disease progresses, more serious symptoms emerge, including:

Persistent cough: This is often the most prominent early symptom, sometimes worsening after exercise.

Difficulty breathing: Shortness of breath, especially during exertion, is a common sign of heartworm disease’s impact on the respiratory system.

Fatigue and lethargy: Infected dogs may exhibit decreased energy levels, reluctance to exercise, and general listlessness.

Weight loss: Despite a normal or increased appetite, dogs with heartworm disease often experience unintentional weight loss.

Fainting or collapse: In advanced stages, the compromised heart function can lead to fainting episodes or sudden collapse.

Swollen abdomen (ascites): Fluid accumulation in the abdomen is a symptom of advanced heart failure, a common complication of severe heartworm disease.

Edema (swelling): Fluid buildup in the legs, especially the lower limbs, indicates advanced heart failure.

Heart murmur: A veterinarian may detect an abnormal heart sound (murmur) during auscultation, indicative of the parasite’s presence and its impact on the heart.

Diagnosing Heartworm Disease

Accurate diagnosis is essential for effective treatment. Your veterinarian will employ various methods, often including:

Physical Examination: A thorough physical exam will assess the dog’s overall health, noting symptoms like cough, respiratory distress, and heart murmurs.

Blood Test (Antigen Test): This test detects the presence of heartworm antigens (proteins produced by adult heartworms) in the dog’s blood. This is the most common and reliable method for detection.

Microfilaria Test: This blood test aims to detect the presence of microfilariae (baby heartworms) in the bloodstream. However, this test may yield a false negative result if the dog is not shedding microfilariae or if the infection is very recent.

Radiography (X-rays): Chest X-rays can reveal changes in the heart and lungs, providing additional evidence of heartworm infection.

Echocardiogram (Ultrasound): This more advanced imaging technique provides detailed images of the heart’s structure and function, helping assess the severity of heartworm-related damage.

Treatment Options for Canine Heartworm Disease

Treatment for heartworm disease is a multifaceted process and requires close monitoring by a veterinarian. The goal is to eliminate adult heartworms while minimizing the risk of serious complications. The treatment typically involves several stages:

Preliminary Assessment: Before initiating treatment, the dog’s overall health is carefully assessed, paying particular attention to the severity of the heartworm infection and the presence of any concurrent health conditions, like kidney or liver disease.

Adult Worm Elimination: The primary treatment involves administering adulticide medication, such as melarsomine dihydrochloride (Immiticide). This medication kills adult heartworms. The administration of this drug should only be done under strict veterinary supervision due to the risk of serious complications, like sudden death. The treatment involves multiple injections spaced out over several weeks.

Microfilaricide Treatment: After the adulticide treatment, medications like doxycycline or ivermectin can help kill microfilariae, thus reducing the number of developing worms in the blood.

Supportive Care: Throughout the treatment process, supportive care is crucial. This might include medications to manage symptoms like cough, pain relievers, and fluids. Dogs might also need supplemental oxygen therapy depending on the severity of the disease. The veterinarian will carefully monitor the dog’s progress, assessing heart and lung function throughout treatment and post-treatment recovery.

Exercise Restriction: Rest is incredibly important during treatment to prevent the death of the heartworms from causing emboli (blockages) in the blood vessels. Strict exercise restriction must be followed for several months after adulticide treatment to minimize the risk of adverse events.

Post-Treatment Monitoring:

Even after successful treatment, ongoing monitoring is essential. Regular blood tests and examinations help ensure the absence of remaining heartworms and monitor the dog’s cardiovascular health.

Prevention of Heartworm Disease

Preventing heartworm disease is significantly easier and less costly than treating it. Prevention involves monthly administration of heartworm preventative medication, typically in chewable or topical forms. These medications are widely available from veterinarians and should be started early in a puppy’s life and continued throughout its adult years. The choice of preventative medication will depend on the dog’s individual health status and age. It’s also important to minimize mosquito exposure by limiting outdoor time during peak mosquito activity, using mosquito repellents, and ensuring proper drainage around the house to reduce breeding grounds.

Conclusion

Heartworm disease is a serious but treatable condition. Early detection through regular veterinary checkups and prompt treatment under the guidance of a veterinarian can significantly improve a dog’s prognosis. Prevention through responsible medication is the most effective strategy to safeguard your dog’s health and well-being. Never attempt to self-treat heartworm disease; always consult a veterinary professional for diagnosis and treatment.