Person giving heartworm treatment to small white dog

Heartworm treatment

Heartworm is a parasite that can be very dangerous to your dog. Here’s what you should know.

Heartworm larvae, transmitted by the bite of a mosquito, travel the bloodstream to lodge in the heart and pulmonary arteries of dogs, causing a potentially fatal disease.1

If your dog has been diagnosed with heartworm, there are steps you can take.

Heartworm disease is difficult to treat2

Steps in diagnosing and treating heartworm disease:

1. Clinical signs: The dog may have symptoms such as coughing, distended abdomen, listlessness, weight loss, and difficulty breathing.

2. Testing: Blood and serum tests can confirm the presence of heartworms.

3. Evaluation: A thorough medical exam is required, including radiographs and potentially ultrasound, to determine the extent of the disease.

4. Medication: In separate appointments, medication is administered to kill adult heartworms. Treatment protocols vary, so your veterinarian will advise on what’s best for your pet.

5. Hospitalization: During heartworm treatment, hospitalization may be necessary to ensure the dog’s complete inactivity and close monitoring. This allows for proper management of the body’s inflammatory reaction as the worms die and break down in the lungs.3

6. Surgery: In some cases, surgery may be required to remove extensive heartworm buildup. This is costly and dangerous.

7. Confinement: To avoid the possibility of dead heartworms causing blood clots or other serious complications, strict exercise restriction is required during treatment.

8. Survival: Subsequent blood tests and other tests are required to confirm the success of the treatment. Not all dogs will survive this grueling treatment regimen.

Prevention is key

Like so many animal health issues, the best way to control heartworm disease is to prevent it from happening in the first place. Talk to your veterinarian about monthly heartworm medication, such as SENTINEL® Spectrum® Chews (milbemycin oxime/lufenuron/praziquantel), SENTINEL® Flavor Tabs® (milbemycin oxime/lufenuron), or Tri-Heart® Plus Chewable Tablets (ivermectin/ pyrantel).

Get your dog tested for heartworm

Before starting a preventive program, all dogs that could possibly be affected by mature heartworms should be tested, as preventive medicines may cause severe reactions in dogs that are already hosts to adult heartworms. A dog that is on preventive medicine should be tested routinely to ensure ongoing protection — especially when a dose has been missed or forgotten.4


  1. Heartworm Basics. American Heartworm Society.
  2. Atkins, Clarke E. Heartworm Disease in Dogs, Cats, and Ferrets. Merck Manual Veterinary Manual.,-cats,-and-ferrets
  3. Heartworm Disease. American Veterinary Medical Association.
  4. An Ounce of Prevention is Worth a Pound of Cure: Protect Your Pet from Heartworms Year-Round. U.S. Food and Drug Administration.


SENTINEL® SPECTRUM® Chews (milbemycin oxime/lufenuron/praziquantel). Dogs should be tested for heartworm prior to use. Mild hypersensitivity reactions have been noted in some dogs carrying a high number of circulating microfilariae. Treatment with fewer than 6 monthly doses after the last exposure to mosquitoes may not provide complete heartworm prevention. For complete product information refer to the product insert.
SENTINEL® FLAVOR TABS® (milbemycin oxime/lufenuron). Dogs should be tested for heartworm prior to use. In a small percentage of treated dogs, digestive, neurologic, and skin side effects may occur. For complete product information refer to the product insert.

Tri-Heart® Plus Chewable Tablets (ivermectin/ pyrantel). All dogs should be tested for existing heartworm infection before starting treatment with Tri-Heart® Plus which is not effective against adult D. immitis. Infected dogs must be treated to remove adult heartworms and microfilariae before initiating a program with Tri-Heart® Plus. For complete product information refer to the product insert.

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