So your dog or cat has been diagnosed with heartworm disease, now what? For dogs, there are approved medications and well established guidelines about how to treat depending on the severity of their disease. For cats, things are a bit trickier since there are no approved treatments for heartworm infection in cats. This is why prevention is so critical.
Let’s cover the basics of treatment for each species individually.
Dogs
Once a diagnosis has been made, your veterinarian will want to perform some additional tests to get a better idea of how much, if any, damage has already occurred. The reason behind this approach is that the severity of the changes can help gauge the risk for complications. However, even dogs with mild changes can develop complications and will need to be monitored closely. One the most important things that you can do as a pet parent once your dog has been diagnosed with heartworm disease is restrict their activity. Exertion can increase the risk for further damage and increase the chance of complications either before or during therapy.
Heartworm disease in dogs is typically classified as:
| Mild | No clinical signs or minimal clinical signs |
| Moderate | May have a cough or exercise intolerance, abnormal lung sounds during physical exam |
| Severe | Cough, exercise intolerance, anemia, abnormal lung sounds during physical exam, enlarged liver, or fluid in the abdomen |
| Caval syndrome | Sudden onset of severe weakness, collapse, discolored urine |
Prior to heartworm therapy, your veterinarian will prescribe an antibiotic called doxycycline or minocycline. This medication helps eliminate a bacteria carried by the heartworms that can cause complications during therapy. Your veterinarian may also recommend a medication at this time to begin to kill off any baby heartworms (microfilariae) as well.
Therapy to kill the adult heartworms will involve a medication called melarsomine which is given as a series of 3 injections over the course of 1 month. Your dog will get one injection then another 2 injections, 24 hours apart, 30 days later. In addition to STRICT EXERCISE RESTRICTION, your veterinarian may also prescribe an anti-inflammatory medication during this time to help decrease inflammation that may occur as a result of the dying worms.
About 6 months after treatment, your veterinarian will perform a blood test to confirm that all of the adult worms have been eliminated.
Cats
There are no approved drugs to treat cats with heartworm infections. Unlike in dogs, the goal of therapy in cats is not to eliminate worms, but to manage the clinical signs and try to reduce further damage. For cats with clinical signs such as coughing or wheezing, your veterinarian may prescribe an anti-inflammatory medication called prednisolone to help reduce inflammation in the airways.
Radiographs (x-rays) of the chest will also be important to determine the severity of the changes in the lungs and assess progression.
Cats can sometimes overcome a heartworm infection on their own over time so blood tests should be performed every 6 to 12 months in heartworm-positive kitties to see if the infection has cleared.
