New Survey Highlights Heartworm Incidence


More than 4,200 veterinarians from clinics and shelters across the U.S. responded to the request for heartworm data, supplying information from some 3.5 million heartworm tests. In addition, veterinarians completed a survey on their perceptions around heartworm disease in their area and factors contributing to it

Heartworm is everywhere

According to the survey, heartworm infections were diagnosed in all 50 states, with 75 percent of veterinarians reporting positive cases of heartworm in their practices. One in three practitioners stated that heartworm is either a “significant” disease problem (18 percent) or  “one of the most serious diseases affecting their patients” (15 percent). Just over half said they see heartworm cases “occasionally” while only 13 percent reported that they never see heartworm-positive patients.

Compliance key to reducing heartworm incidence

If there’s a silver lining to this unwelcome news, it’s that a simple solution is in the hands of veterinarians and pet owners: getting more pet owners to administer heartworm preventives year-round.

  • Of the one-fifth of veterinarians reporting a decreased rate of heartworm infection in their practice areas, three-quarters of these said the decline was due to more pet owners administering preventives, while two-thirds of this group also cited improved compliance (more year-round usage and more doses given on time).
  • Conversely, among the 19 percent of veterinarians reporting an upward trend in the incidence of heartworm, a majority of these saw poor compliance as the leading causative factor.

Other factors contributing to incidence

While of obvious concern to our profession, product lack of efficacy did not emerge as a major contributing factor to heartworm incidence, in the opinion of veterinarians participating in the survey. Among the 19 percent of those who perceived a rise in incidence, less than 6 percent cited it as a factor. Lack of compliance, wet weather conditions that caused an increase in mosquitoes, and the influx of heartworm-positive rescue dogs into practice areas were considered to be of much greater importance.

The vision of the American Heartworm Society is a world without heartworm. While we’re not likely to see that vision fulfilled for years to come, we can take steps to reduce the incidence of the disease. Every time we put a new pet on heartworm prevention or refill a patient’s medication on time, we make a difference.