Heartworm disease is a serious and potentially fatal condition caused by parasitic worms that live in the heart, lungs, and blood vessels of affected dogs. The disease is transmitted through the bite of an infected mosquito. Early detection and treatment are critical, as untreated heartworm disease can cause severe damage to the heart, lungs, and other organs. In this article, we will discuss how to know if your dog has heartworm, the symptoms to watch for, and what steps to take if you suspect your dog is infected.

What is Heartworm Disease?

Heartworm disease is caused by a parasitic worm called Dirofilaria immitis. These worms are transmitted through the bite of an infected mosquito. Once inside a dog’s body, the larvae grow into adult heartworms that can live for several years. The worms reside in the heart, lungs, and blood vessels, leading to inflammation, tissue damage, and other serious health problems.

If left untreated, heartworm disease can be fatal. However, it is treatable if caught early, which is why it’s important to understand how to recognize the symptoms and seek veterinary care.

How to Know if Your Dog Has Heartworm: Common Symptoms

Heartworm disease can be difficult to detect in its early stages because the symptoms may not appear right away. As the disease progresses, the symptoms become more pronounced. Here are some common signs that may indicate your dog has heartworm:

1. Coughing

One of the most common early signs of heartworm infection is a persistent cough. The worms can cause irritation and inflammation in the lungs and airways, leading to coughing. If your dog has a cough that doesn’t seem to go away, especially if it worsens after exercise, it could be a sign of heartworm disease.

2. Lethargy or Fatigue

Dogs infected with heartworms may become unusually tired or sluggish. If your dog seems to tire easily during walks or playtime, or if they are sleeping more than usual, this could indicate heartworm disease. The heart and lungs are compromised by the presence of the worms, which reduces the dog’s ability to exercise.

3. Difficulty Breathing

As heartworm disease progresses, it can cause difficulty breathing. If your dog is struggling to breathe, has labored or shallow breaths, or seems to be breathing more rapidly than usual, this could be a sign of heartworm-related damage to the heart and lungs. In severe cases, the dog may exhibit wheezing or a collapse due to a lack of oxygen.

4. Loss of Appetite

Infected dogs may lose their appetite due to the discomfort caused by heartworms. If your dog is refusing food or eating much less than usual, it could be a symptom of heartworm disease. Malnutrition and weight loss can occur over time if the infection is not treated.

5. Weight Loss

Weight loss is often seen in dogs with heartworm disease as the worms damage the body’s organs and the dog’s overall health declines. If your dog has lost weight despite eating normally, this could be a sign of heartworm infection or other underlying health issues.

6. Swollen Abdomen

As the disease progresses, dogs may develop a swollen abdomen, which can be caused by fluid buildup in the abdomen due to heart failure. This is a serious sign and requires immediate veterinary attention.

7. Fainting or Collapse

In severe cases of heartworm disease, the dog may experience fainting or sudden collapse. This can occur when the heart is no longer able to pump blood effectively due to the presence of the worms.

8. Heart Murmurs or Abnormal Heart Sounds

During a physical examination, your veterinarian may detect a heart murmur or abnormal heart sounds, which can be a sign of heartworm infection. The presence of adult heartworms in the heart can interfere with normal blood flow and cause murmurs.

Diagnosis of Heartworm Disease

If you suspect your dog has heartworm, it’s important to visit a veterinarian as soon as possible for an accurate diagnosis. There are several methods your vet can use to diagnose heartworm disease:

1. Blood Test: A blood test is the most common way to detect heartworm infection. The test looks for the presence of heartworm antigens (proteins released by female heartworms) or microfilariae (young heartworms). The test is typically done by taking a small blood sample from your dog and sending it to a lab for analysis.
2. Physical Examination: Your veterinarian will listen to your dog’s heart and lungs for any signs of irregularities such as a murmur or abnormal lung sounds. They may also check for signs of fluid retention or other symptoms indicative of heartworm disease.
3. Chest X-rays: In more advanced stages of heartworm disease, chest X-rays can help assess the damage caused to the heart and lungs. The X-rays may reveal enlarged heart chambers, lung damage, or fluid accumulation.
4. Ultrasound: In some cases, an ultrasound of the heart (echocardiogram) may be used to visualize the heartworms directly and assess the severity of the disease.

What to Do If Your Dog Has Heartworm

If your dog is diagnosed with heartworm, it’s important to follow your veterinarian’s instructions carefully. Treatment for heartworm disease typically involves the following steps:

1. Pre-Treatment: Before starting treatment, your dog may need to undergo tests to evaluate their overall health and determine if they are strong enough for treatment. This may include blood tests, X-rays, and an examination of the heart and lungs. Your vet may also recommend starting your dog on a medication to kill any microfilariae (young worms) in the bloodstream.
2. Treatment Protocol: The main treatment for heartworm disease involves administering a series of injections of a medication called melarsomine, which kills adult heartworms. This treatment can take several weeks and may require your dog to be confined to a quiet environment during the recovery process to minimize stress on the heart and lungs.
3. Post-Treatment Care: After treatment, your dog will need to rest for several weeks to allow the body to recover. The dead heartworms will break down and be absorbed by the dog’s body, but this process can be dangerous, as the debris from the dead worms can cause an embolism (blockage) in the lungs. Follow-up blood tests are needed to ensure that all the heartworms have been eliminated.
4. Prevention: The best way to protect your dog from heartworm disease is through preventative medications. There are several options available, including monthly oral medications, topical treatments, and annual injections. These preventatives kill any heartworm larvae before they have a chance to mature into adult worms.

Prevention of Heartworm Disease

Heartworm disease is preventable with proper care and medication. The American Heartworm Society recommends that all dogs, regardless of whether they live indoors or outdoors, be placed on heartworm prevention year-round, particularly if you live in an area where mosquitoes are prevalent.

Heartworm prevention is available in various forms, including:

• Monthly oral medications (e.g., Heartgard, Interceptor)
• Topical treatments (e.g., Revolution, Advantage Multi)
• Annual heartworm injections (e.g., ProHeart 12)

By maintaining a routine heartworm prevention regimen, you can significantly reduce your dog’s risk of contracting heartworm disease.

Conclusion: How to Know if Your Dog Has Heartworm

Heartworm disease is a serious condition that can cause significant harm to your dog if left untreated. Recognizing the symptoms, such as coughing, lethargy, difficulty breathing, and loss of appetite, is key to catching the disease early. If you suspect your dog may have heartworm, consult a veterinarian for a proper diagnosis and treatment plan. With proper care and preventative measures, you can protect your dog from this dangerous disease and help them lead a long, healthy life.