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.
Sheldon Rubin, DVM
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.
WHAT CAN YOU DO?
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
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.