Is Heartworm Prevention Medicine Necessary for Your Dog?

Yes, heartworm preventive medicine is recommended for all dogs at risk of becoming infected with heartworms.

Heartworms are parasites to which all dogs are susceptible. Fortunately, we have numerous forms of heartworm prevention medicines that are not only safe and effective but are also extremely easy to administer.

Is Heartworm Prevention Medicine Necessary for Your Dog?

What Are Heartworms and How Can My Dog Get Infected?

Heartworms are parasitic worms that live inside of the heart and blood vessels. A dog can become infected with heartworms when bitten by an infected mosquito. It only takes one mosquito bite to pass the infection to your dog.

Heartworms can cause a variety of symptoms, including heart failure and even death.

Heartworms are fairly easy to diagnose in a dog. Testing for heartworms is done with a small sample of blood and the results can usually be obtained very quickly, often within a few moments.

Why Is Heartworm Prevention Necessary for My Dog?

Though heartworms are fairly easily diagnosed, they can do a lot of damage to your dog’s heart before the infection is found. This damage may not be reversible.

Heartworm preventive medications are readily available. They are quite effective in preventing infection if administered as directed and are also quite safe

It is possible to treat an existing heartworm infection. However, even under the best of circumstances, treatment is risky for your dog and expensive for you. Treatment of heartworms involves using an arsenic-based medication to kill the adult heartworms living in your dog’s heart. Obviously, this medication can have serious side effects for your dog as well.

In addition, dogs with severe infections and serious damage already inflicted by the heartworms may not even be good candidates for treatment. The risk of complications from the treatment may be quite high for these dogs.

Heartworm treatment can result in fatal complications for your dog, as can the heartworm infection itself. As a result, prevention of a heartworm infection is much safer for your dog.

What Forms of Heartworm Prevention Medicine Are Available for My Dog?

There are several forms of heartworm prevention medicines currently available.

  • There are many oral medications that are administered on a monthly basis to prevent heartworms. Examples of these medications include Heartgard Plus®, Interceptor®, Iverhart Plus® and Iverhart Max®, and many others.
  • There are also several topical heartworm prevention medicines that are applied to the skin on a monthly basis. These products include Revolution® and Advantage Multi®.
  • Proheart 6® is an injection that is administered by your veterinarian every six months to prevent heartworms. This medication is still somewhat controversial in the United States and is not as widely used as the oral and topical medications. It is not available through all veterinarians but some veterinarians do offer it as an alternative method of heartworm prevention. There are, however, strict protocols governing its usage at the current time.

Heartworm infections are more common in some areas of the countries than they are in others. For instance, in many of the southern states, the incidence of heartworm infection is quite high. However, heartworm infections have been found in all areas of the United States. As a result, heartworm prevention medicine is recommended for all dogs.

About Lorie Huston, DVM

Lorie Huston, DVM has written 88 posts in this blog.

Lorie Huston is a veterinarian with 20+ years of experience with dogs and cats. She is also a talented free-lance author and blogger and has contributed to numerous publications, including Pet Sitter's WORLD, FIDOFriendly, Dancing Dog Blog, Dawg Business and many others. Lorie is the featured pet care writer at, a contributing writer in Dog and Cat Diseases and Conditions at and the National Pet Health Examiner at In addition, she is a host of the popular podcast/review site, Animal Cafe.



  1. says

    This is a great post. You absolutely need to give heartworm prevention every month regardless of your climate. After working in a Veterinary Clinic for 10 years, I will tell you that heartworm disease is a horrible way to die. I understand that it may become expensive but the prevention is much cheaper than the treatment.

    Another one that we get often — “My dog never goes outside” You still need to give heartworm prevention because mosquitoes can come inside. It only takes one mosquito!


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