Written by: Rachel Holly
Vet-reviewed by: James Reynolds, DVM, Williamson Co. Animal Hospital
Heartworm disease is a serious and potentially fatal condition affecting dogs. It is caused by a parasitic worm called dirofilaria immitis which is transmitted through the bite of an infected mosquito. While heartworm disease poses a significant threat to a dog’s health, understanding transmission, symptoms, prevention, and treatment can help dog owners protect their canine friend from this devastating disease.
How Do Dogs Get Heartworm Disease?
Heartworms are parasitic worms that are transmitted when an infected mosquito bites a dog. The life-cycle of the heartworm involves several stages. First is the introduction of the microfilariae (immature heartworms) into the dog’s bloodstream. These microfilariae mature into the next stage as larvae and travel to the heart and pulmonary arteries. After six months, the larvae grow into adult heartworms, which can measure up to 12 inches.
Symptoms of Heartworm Disease in Dogs
Heartworm disease often progresses slowly, with symptoms developing gradually. Early stages may show no obvious signs, making regular veterinary check-ups crucial. As the disease advances, symptoms become more noticeable and severe. Be on the look out for:
Coughing – persistent and dry
Exercise Intolerance– abnormal fatigue from exertion and activity
Respiratory Distress
Weight Loss
Bloating – caused by fluid buildup
Sudden Collapse – In severe cases, dogs may suddenly collapse or faint
Diagnosis of Heartworms in Dogs
To diagnose heartworm disease, veterinarians perform a series of tests, including:
Blood Tests – The most common test is the heartworm antigen test, which detects proteins released by female adult heartworms. Additionally, a microfilariae test might be conducted for a more definitive diagnosis.
X-rays – can be used to view the impact of heartworms on the heart and lungs.
Treatment for Heartworms in Dogs
If a dog is diagnosed with heartworm disease, veterinary treatment is necessary to eliminate the worms and prevent severe health complications. Without treatment the disease is fatal. The treatment process involves several stages:
Stabilization– Before initiating the primary treatment, your vet may stabilize your dog, especially in the case of severe symptoms like heart failure or respiratory distress. Adulticide Therapy – This is the main treatment for canine heartworm disease. It is an injectable medication called melarsomine. This drug targets and kills adult heartworms residing in the heart and pulmonary arteries. While it may sound simple, this treatment can be hard on the patient due to the high risk of complications, such as an embolism.
Microfilaricide Treatment – After adult heartworms are eliminated with the adulticide treatment, a microfilaricide is used to clear any remaining microfilariae from the bloodstream. Microfilaricide is an important part of the heartworm treatment and
will be used throughout the heartworm treatment.
Exercise Restriction – Dogs must be kept on restricted activity to prevent serious complications and allow the body to respond to treatment.
Regular Checks – Regular monitoring during recovery is required to ensure the complete elimination of the parasites. Re-testing will be needed to confirm the treatment was successful.
Preventing Heartworm Disease in Dogs
Preventing heartworm disease is significantly easier and far less expensive than treating it. There are several effective methods of prevention:
Monthly Preventatives – Heartworm preventatives are available both in oral and topical form. These medications kill heartworm larvae before they mature into adults.
There are also injectable heartworm preventatives in 6 month and 12 month formulations. If you have trouble getting your dog to eat the chewable variety, this may be a good option.
Regular Vet Visits– Annual or semi-annual veterinary check-ups with heartworm tests will help your dog remain heartworm-free.
Controlling Mosquito Exposure– While hard to do in the peak of summer, try reducing your dog’s exposure to mosquitoes. This can include using mosquito repellents designed for pets and eliminating standing water around your home that mosquitoes are attracted to.
Conclusion
Heartworm disease is a potentially deadly condition for dogs but with proper prevention it can hopefully be avoided in your dog. By understanding the life-cycle of heartworms, recognizing the symptoms, and committing to regular preventative measures, dog owners can protect their pets from this serious illness. If you suspect your dog might have heartworm disease or if you’re unsure about their preventive care, consult with your veterinarian to ensure your canine companion remains healthy and heartworm-free.
