You’ve noticed that your dog has been lethargic lately and not interested in going for walks; maybe he’s been eating less and losing weight. You take him into your vet, who runs a few diagnostic tests and comes back with bad news – your dog has heartworms.
So now what?
First, don’t panic. A heartworm diagnosis is a scary thing for a pet parent, but with early detection and the right treatment, the majority of healthy dogs will recover from heartworms completely.
After your vet confirms the heartworm diagnosis, your dog will need to be stabilized to ensure that he is healthy enough for the heartworm treatment to be effective. Your main job at this point is to put your dog on bed rest! Physical activity can speed up the damage to your dog’s heart and lungs, so you will need to restrict your dog’s exercise. This may mean crating or otherwise confining your dog, particularly when you aren’t there to monitor him. Bed rest can be frustrating for both you and your dog, but reducing physical activity is an essential step in ensuring your dog’s full recovery from heartworm infection. Providing your dog with some new chew toys and making sure he has plenty of human interaction throughout the day can help prevent boredom!
If your dog has a severe case of heartworm or has other underlying medical conditions, other therapies may be necessary before beginning heartworm treatment. These can include treating heart or lung damage or improving kidney or liver function to ensure that the drugs administered for the heartworms can safely pass through your dog’s system.
The heartworm treatment protocol recommended by the American Heartworm Society involves several steps. Your veterinarian may start by prescribing a course of antibiotics and/or corticosteroids to kill off bacteria commonly released by heartworms into infected dogs’ bodies and to reduce dangerous inflammation. Initial heartworm treatment also often includes a two-month course of heartworm preventive medications to kill off smaller heartworm larvae and to prevent your dog from picking up any new heartworm infection during treatment.
After these initial medications are complete, your dog will begin receiving injections (typically of a drug called melarsomine) to kill the adult heartworms. Injections are given at your vet’s office or at a veterinary hospital, and your dog will often be required to stay overnight to be monitored for any adverse reaction. Treatment of adult heartworms in dogs can take anywhere from one to three months.
Newer heartworm treatment protocols also include a course of drugs to kill off baby heartworms, or microfilarie; your vet will recommend the most appropriate drug based on your dog’s health and prognosis. This phase of the treatment typically begins one month after treatment for the adult worms. As with the injections for adult heartworms, your dog will need to be hospitalized for a day or so for observation.
Finally, after your dog has been treated for heartworms, he will need to be retested for heartworm infection immediately after his treatment ends and six months later to make sure that all of the heartworms – larvae, babies, and adults – have been eliminated. If your dog still tests positive for heartworm six months after being treated, he may need to undergo a second round of treatment. Once your dog tests negative for heartworm infection, he will need to be restarted on a monthly heartworm prevention medication to prevent future infections.
The two most important things you can do if your dog has been diagnosed with heartworm are to follow your vet’s instructions carefully and to keep your dog as calm and inactive as possible, both during treatment and for several weeks afterward. Your vet will let you know when it is safe for your dog to resume his normal active life.
To learn more about the symptoms, diagnosis, treatment, and prevention of canine heartworms, visit our Education page: What Is Canine Heartworm, and How Do I Know If My Dog Has Heartworm?