I’ve talked about heartworm prevention a million times, and I’ve heard all of the excuses. Clients say: “not my dog, she’s not at risk for this! She only goes outside to go potty.”
But, heartworm disease IS a risk for your dog, and it can make a huge dent in your pocketbook. In this post, I will explain heartworm treatment and why prevention is a much better option.
Cats can get heartworm disease. For more on this disease and its effect on cats, check out our previous blog post on Feline Heartworm Disease.
What is Heartworm Disease?
Let’s refresh your memories about heartworm disease itself. Heartworm disease is transmitted by mosquitos. All it takes is one infected mosquito to bite your pet and spread the disease. Have you ever had a mosquito in your home? “Inside” pets are still at risk for heartworm!
From the time the infected mosquito bites your dog to the time that your vet can detect the disease is about six months. In the early stages of heartworm disease, there typically are no major outward signs or symptoms. However, during those six months, worms are traveling to your dog’s lungs and heart where they continue to increase in size and number.
What Do Heartworms Do?
As time passes, the worms continue to grow and produce more worms. These worms then affect blood circulation through the heart and lungs. When this happens, your dog may start coughing and may have difficulty with physical activity.
In later stages of the disease, so many worms inhabit your pet’s heart and lungs that her blood cannot flow to these organs properly. This lack of blood flow can cause permanent damage and irreversible damage.
This disease can cause permanent health problems or even death for your dog.
Heartworm Treatment is Difficult
The treatment is neither simple nor quick. We can’t give your dog a pill or a shot to “fix” her. The current treatment protocol recommended by the American Heartworm Society actually lasts 271 days! That time frame translates to nine months!
To begin, we will give your dog an antibiotic to prevent anaphylactic side effects from the treatment. We want to minimize the likelihood of respiratory problems, hives, and other allergic reactions to the medication we use in heartworm treatment.
The actual treatment to kill the heartworms itself involves a series of injections of Immiticide (Melarsomine).
We use a long needle to inject the medication deep into your dog’s lower back muscles, and this can be very painful for your pup.
After the injections of Immiticide, we send your pet home with steroidal medication to prevent inflammation, provide pain relief, and minimize the side effects of the injection.
You will need to keep your dog confined to a kennel or a small room in order to keep her quiet. Keep her on a leash to take her out to go potty. You can’t let her loose around the yard, because she might chase a bird or a squirrel. Any strenuous activity can increase the pet’s blood pressure and blood flow and may cause worm fragments to get lodged blood vessels of the lungs or brain.
Over the course of the treatment, we will perform a blood test to see if there are microfilaria (baby heartworms) in your dog’s bloodstream. If the treatment is going well, she should test negative for microfilaria. That means the adult heartworms are not reproducing.
At another point, later in the process, we will test for both microfilaria and adult heartworms. When your dog is free from both the babies and the adult worms, she can begin to ease into physical activity again.
The Treatment Takes its Toll on You, Too!
Treatment of heartworm disease is hard on your pet, but it can be difficult for your family as well. You worry about the severity of the disease and its effect on your dog. You feel bad seeing her discomfort during the injections.

Photo by Ayla Verschueren on Unsplash
In addition, it is extremely hard to keep your pet quiet for nine months, especially when she starts feeling better and wants to play. This process takes its toll not only on your dog but also on you.
Heartworm Treatment is Expensive
In addition to the emotional stress of this treatment, there is significant financial stress for families going through this process. The cost of the medications, the injections, the tests, and the clinic visits can add up quickly.
Unfortunately, the medications and injections needed for heartworm treatment are costly. The larger the dog, the more expensive the treatment since bigger dogs need more of the medications. The entire treatment process can run well over $1,300, but heartworm prevention for one entire year is $138 (for the largest dose of Sentinel).
Heartworm Prevention is Much Better Than Treatment!
Prevention is always the key to keeping your pet healthy. In comparison, heartworm prevention medicine is far less expensive with far fewer side effects than the treatment for the disease.
Heartworm disease is a true risk for all dogs no matter what their lifestyle is. All dogs in our area have the risk of being exposed to mosquitoes. At our clinic, we see numbers of heartworm-positive pets increasing steadily over the years.
Currently, we already treating three heartworm-positive dogs and it’s only the beginning of May. The next time you hear your vet talk to you about heartworm and heartworm prevention, please listen closely! Get that heartworm prevention refilled to help keep your pet healthy and happy.
Dr. Heintz is a small and exotic animal veterinarian at Countrycare Animal Complex in Green Bay, WI. She earned her Doctor of Veterinary Medicine from the University of Illinois – Urbana/Champaign. Her passion is helping all animals, whether furry, scaly, or feathered, lead long and healthy lives.