Editors' Guest: Protecting pets' hearts: Revised heartworm guidelines


Editors' Guest: Protecting pets' hearts: Revised heartworm guidelines

May 01, 2012

Sheldon Rubin, DVM
With all the information, technology, and medications available today to help prevent heartworm disease, one would assume that the prevalence of the disease would be declining. The opposite is true. Heartworm disease has been diagnosed in pets in all 50 states, sales of heartworm preventives are decreasing, and the number of heartworm cases is increasing. Something has to change.

Heartworm disease is deadly—but preventable. That's why the American Heartworm Society (AHS) created canine and feline guidelines, which are peer-reviewed and periodically updated to ensure they include the latest information. Newly revised guidelines were released early this year and are available on the AHS website at http://heartwormsociety.org/. It is our hope that every practicing veterinarian will follow these peer-reviewed procedures.


The foundational recommendations of the AHS guidelines cover heartworm testing and prevention. We emphasize annual antigen testing of dogs and recommend that all antigen-positive dogs be tested for the presence of microfilariae. Our guidelines also underscore the importance of year-around administration of preventives to all dogs and cats. Microclimates and the increased mobility of our pets have created large reservoirs of heartworm in areas that historically were low.

The guidelines also cover treatment and recommend a multimodal approach. Infected dogs should be pretreated with a monthly preventive in combination with doxycycline before administration of melarsomine. The three-dose regimen of melarsomine for treating heartworm disease is recommended for both symptomatic and asymptomatic dogs. We strongly recommend against using macrocyclic lactones as an adulticide (slow-kill).

New this year is a discussion of lack of efficacy. AHS supports continuing research into reports of lack of efficacy to determine if these represent true resistance. Today, however, we believe that most suspected heartworm preventive failures are the result of inadequate compliance with prevention and testing protocols. Macrocyclic lactones continue to be the best—and only—option for preventing heartworm infections. Veterinarians need to make efforts to increase the number of dogs receiving chemoprophylaxis and assist pet owners in purchasing and administering products in compliance with veterinary recommendations.


Along with adhering to AHS guidelines regarding annual testing and year-round prevention, we recommend taking stock of your practice's reminder systems and client education programs. Chances are, you have a system in place to remind clients of the need for annual heartworm testing and heartworm medication refills. However, statistics from the American Animal Hospital Association tell us that less than half of dog owners—and even fewer cat owners—buy protection at all, while most do not buy 12 months of protection.

Education is vital. Visual aids can be compelling, so you may want to retrieve that jar of heartworms gathering dust in your cabinet. Printed handouts and in-clinic videos are also effective. AHS recently initiated a program called "Think 12 in 2012," which includes an online resource center through which you can download free materials for educating both staff and clients. New information will be posted every month at http://heartwormsociety.org/think12/.

The vision of the AHS is a world without heartworms. While eradication of heartworm disease is not yet on the horizon, reversing the present trend is something we can all do now.

Sheldon Rubin, DVM, is director emeritus of Blum Animal Hospital in Chicago and president of Veterinary Consulting, LTD, offering services to practice, industry, government, and media. He is immediate past president of the American Heartworm Society.