Symptoms Of Late-Stage Heartworms In Dogs

Symptoms of Late-Stage Heartworms in Dogs

Heartworm disease is a serious and potentially life-threatening condition caused by parasitic worms that live in the heart and pulmonary arteries of infected animals, primarily dogs. While early-stage heartworm infections may not show obvious symptoms, late-stage infections can lead to severe complications and a range of debilitating symptoms. In this comprehensive article, we will explore the symptoms of late-stage heartworms in dogs, the importance of early detection, and the available treatment options.

Understanding Heartworm Disease

Heartworm disease is caused by the parasitic worm Dirofilaria immitis, which is transmitted by infected mosquitoes. When a mosquito bites an infected animal, it ingests immature heartworms called microfilariae. These microfilariae develop into infective larvae within the mosquito and are then transmitted to a new host during the mosquito’s next blood meal.Once inside a dog’s body, the larvae migrate to the heart and surrounding blood vessels, where they mature into adult worms. Adult heartworms can grow up to 12 inches long and live for 5 to 7 years in dogs.

Symptoms of Late-Stage Heartworms

As the infection progresses, the number of adult worms in the heart and pulmonary arteries increases, leading to more severe symptoms. Late-stage heartworm disease is characterized by the following symptoms:

Coughing and Exercise Intolerance

One of the earliest and most common symptoms of late-stage heartworms is a persistent cough, especially after exercise or excitement. As the worms grow larger and obstruct blood flow, the dog’s breathing becomes more labored, and it tires more easily during physical activity.

Weight Loss and Decreased Appetite

Late-stage heartworm infections can cause significant weight loss and a decreased appetite in affected dogs. The worms place a strain on the dog’s heart and lungs, making it difficult for the body to maintain a healthy weight and appetite.

Swelling in the Abdomen

As the disease progresses, fluid may accumulate in the abdomen, causing a swollen appearance. This condition, known as ascites, is a result of the heart’s inability to pump blood effectively due to the presence of the worms.

Fainting or Collapsing

In severe cases, late-stage heartworm infections can cause the dog to faint or collapse, especially during exercise. This is due to the heart’s inability to pump enough blood to meet the body’s demands, leading to a sudden drop in blood pressure and oxygen supply to the brain.

Difficulty Breathing

As the worms grow larger and obstruct blood flow, the dog may experience difficulty breathing, especially when lying down. This is a result of the increased pressure in the pulmonary arteries, which can cause fluid to accumulate in the lungs (pulmonary edema) or the chest cavity (pleural effusion).

Pale Gums and Rapid Heart Rate

Late-stage heartworm infections can cause the dog’s gums to appear pale or white, and its heart rate may be faster than normal. These symptoms are a result of the heart’s struggle to pump blood effectively due to the presence of the worms.

Diagnosing Late-Stage Heartworms

Diagnosing late-stage heartworms typically involves a combination of physical examination, blood tests, and imaging techniques. A veterinarian may perform the following tests to confirm the diagnosis:

• Blood tests to detect the presence of heartworm antigens or microfilariae
• X-rays of the chest to look for enlargement of the heart and pulmonary arteries
• Echocardiography (ultrasound of the heart) to visualize the worms and assess the extent of damage to the heart and surrounding blood vessels

Treatment Options

Treatment for late-stage heartworms is more complex and carries a higher risk of complications compared to early-stage infections. The treatment process typically involves the following steps:

1. Stabilization: The dog may be given medications to reduce the risk of complications and improve its overall health before treatment begins.
2. Adulticide treatment: The dog is given a series of injections of an arsenic-based medication called melarsomine to kill the adult worms. This treatment is often preceded by a course of macrocyclic lactone preventives to reduce the number of circulating microfilariae and minimize the risk of complications.
3. Surgical extraction: In some cases, particularly when the worms are located in the pulmonary arteries, a veterinary surgeon may attempt to remove the worms surgically.
4. Post-treatment care: After treatment, the dog is monitored closely for any complications, such as blood clots or inflammation in the lungs. The dog may be placed on restricted activity for several months to allow the body to heal and the worms to be cleared from the system.

Preventing Heartworm Disease

The best way to manage heartworm disease is to prevent it in the first place. Veterinarians recommend the following preventive measures:

• Administering monthly heartworm preventive medications to dogs
• Using mosquito repellents and keeping dogs indoors during peak mosquito activity hours
• Having dogs tested for heartworms annually, even if they are on preventive medications

FAQs

Q1: How do dogs get heartworms?

Dogs get heartworms through the bite of an infected mosquito. When a mosquito bites an infected animal, it ingests immature heartworms called microfilariae, which develop into infective larvae within the mosquito.

Q2: Can heartworm disease be cured in dogs?

Yes, heartworm disease can be treated in dogs, but treatment is more complex and carries a higher risk of complications in late-stage infections. Treatment typically involves a series of injections of an arsenic-based medication called melarsomine to kill the adult worms.

Q3: How long can a dog live with untreated heartworms?

The lifespan of an untreated dog with heartworms depends on the severity of the infection. In some cases, dogs may live for several years with untreated heartworms, but the disease will eventually lead to heart failure and death.

Q4: Can a dog survive heartworm treatment?

Yes, most dogs can survive heartworm treatment, but the success rate depends on the severity of the infection and the dog’s overall health. Veterinarians will carefully monitor the dog throughout the treatment process and provide supportive care to minimize the risk of complications.

Q5: How can I prevent my dog from getting heartworms?

The best way to prevent heartworms in dogs is to administer monthly heartworm preventive medications, use mosquito repellents, and have your dog tested for heartworms annually, even if they are on preventive medications.

Table: Stages of Heartworm Disease

Conclusion

Late-stage heartworm disease in dogs is a serious and potentially life-threatening condition that requires prompt diagnosis and treatment. By being aware of the symptoms of late-stage heartworms, such as persistent coughing, exercise intolerance, weight loss, and difficulty breathing, dog owners can seek veterinary care early and improve their dog’s chances of a successful recovery. Regular preventive measures, including monthly heartworm medications and annual testing, are essential to protect dogs from this devastating disease.