Skip to Main Content
Ask About Financing

Heartworm in Dogs

Heartworm in Dogs

Heartworm disease is a serious, often fatal condition that can cause severe lung disease, heart failure, organ damage, and other complications in dogs. Our Oak Grove veterinarians explain why preventing heartworm disease is better for your pet and cheaper than treating it after your dog becomes ill.


Heartworm disease is caused by a parasitic worm called dirofilaria immitis which is primarily spread through the bite of an infected mosquito.

Once infected, your dog becomes a 'definitive host' for this parasite, which means the worms mature, mate, and reproduce. Because these worms live in the heart, lungs, and blood vessels of infected pets, this serious condition is known as heartworm disease.

Signs of Heartworm in Dogs

Unfortunately, no early warning signs of heartworm disease exist. Symptoms of this condition appear in dogs only after the disease has progressed to a more advanced stage. When symptoms do appear, they are as follows: fatigue, swollen abdomen, coughing, difficulty breathing, and weight loss.

Diagnosing Heartworm 

Blood tests can be performed at your veterinarian's office to detect heartworm antigens, which are released into the animal's bloodstream. However, these antigens are not detectable until your pet has been infected for approximately 6-7 months. Your veterinarian will also look for clinic signs of heartworm infection, such as fluid buildup in your dog's lungs, a swollen abdomen, coughing (in some cases, coughing up blood), and overall poor health.

Treatment for Heartworm Disease in Dogs

The reason that prevention is so important when it comes to heartworm is that the treatment for this disease can be toxic and may cause serious health complications for your pet. Not only that, treatment is can be expensive because it requires multiple visits to the vet, bloodwork, x-rays, hospitalization, medications, and a series of injections.

If your dog has heartworms, your veterinarian may recommend a 4-week course of doxycycline followed by three doses of melarsomine dihydrochloride (an arsenic-containing drug that kills adult heartworms). In order to kill the parasites, melarsomine dihydrochloride is injected into the dog's back muscles. The vet may also prescribe sedation medication to help your dog remain relaxed during the injection process.

In cases where immature parasites could be present your dog may also be treated with heartworm preventive medication for 2 months before beginning the melarsomine treatment.

Prednisone is also frequently prescribed for dogs during the melarsomine treatment to help prevent complications. Strict crate rest is essential throughout your dog's heartworm treatment.

Heartworm Prevention

Keeping your dog on preventative medication is the most effective way to keep heartworm disease at bay. Even if your dog is already on heartworm prevention medication, it is recommended that dogs be tested for this parasite on an annual basis.

Heartworm prevention is safer, easier, and much more affordable than treating the progressed disease. A number of heartworm preventive medications can also help to protect your dog against other parasites such as hookworms, whipworms, and roundworms.

Note: The advice provided in this post is intended for informational purposes and does not constitute medical advice regarding pets. For an accurate diagnosis of your pet's condition, please make an appointment with your vet.

Find out how to protect your dog against heartworm disease. Contact our Oak Grove vets today to book an appointment for your pet.

We Are Always Welcoming New Patients

Oak Grove Animal Hospital is accepting new patients! Our veterinarians are passionate about animal health and are proud to serve our patients. Contact us today to book your pet's first appointment and to get started.

Contact Us

Contact (270) 439-6110