Heartworm Disease in Pets Diagnosed Nationwide

American Heartworm Society survey highlights need for year-round prevention

This heartworm incidence map, released by the American Heartworm Society, is based on a nationwide survey of more than 4,300 veterinary practices and shelters. (Graphic: Business Wire)

WILMINGTON, Del.--()--No state is heartworm-free, according to a heartworm incidence survey just released by the American Heartworm Society (AHS). Three out of four veterinarians participating in the nationwide survey diagnosed dogs with heartworm disease in 2013, and the disease was found in all 50 states.

The AHS has surveyed veterinarians every three years since 2001 to track trends in heartworm incidence and inform veterinarians and the public about the need for heartworm prevention. The latest survey, which was conducted in March of 2014, represents 2013 testing data from 3.5 million patients from more than 4,300 veterinary clinics and shelters.

“Our survey determined that heartworm disease continues to be widespread in many parts of the country,” said AHS president Stephen Jones, DVM. “The silver lining to this unwelcome news is that a simple solution is in the hands of veterinarians and pet owners: getting more pet owners to give their pets heartworm preventives year-round.”

The American Heartworm Society recommends heartworm prevention for pets 12 months a year and heartworm testing once a year.

Survey identifies heartworm trends, contributing factors
Along with submitting data from clinic heartworm tests, participating veterinarian were surveyed about the significance of heartworm disease in their practice areas and factors contributing to the disease’s incidence. Findings included:

  • Heartworm is everywhere. While veterinarians from the Gulf Coast and Mississippi Delta states reported the highest incidence rates of heartworm disease in dogs in the country, relatively high rates also were noted in areas less well known for heartworm risk. These included the Upper Midwest—especially the states of Michigan, Illinois, Indiana and Ohio—and the western states of Arizona and California.

    Sixty percent of veterinarians stated that the incidence of heartworm disease in their practice areas has held steady since the last AHS survey was conducted three years ago. A roughly equal proportion of veterinarians said that incidence is up (19 percent) and down (21 percent) in their practice areas.
  • Heartworm disease concerns veterinarians. One-third of veterinarians 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 of surveyed practitioners reported they see heartworm cases “occasionally,” while only 13 percent said they never see heartworm-positive patients.
  • Prevention is key. Veterinarians who witnessed either an upward or downward trend in heartworm disease were asked about multiple factors related to those trends. But whether heartworm rates increased or decreased, the same factor was identified as key to the change: prevention practices. Nearly two-thirds of veterinarians who reported an upward trend in heartworm diagnoses cited “poor compliance”—defined as not administering preventives year-round or skipping doses—as the leading cause. Meanwhile, three-quarters of veterinarians who reported a drop in heartworm rates said the leading reason was “more pet owners administering preventives.”

“Heartworm is a devastating but preventable disease. If we make consistent, year-round prevention in dogs and cats a priority, we will see incidence go down,” concluded Dr. Jones.

For more information on heartworm disease, visit www.heartwormsociety.org.

About the American Heartworm Society

The mission of the American Heartworm Society is to lead the veterinary profession and the public in the understanding of heartworm disease. Founded during the Heartworm Symposium of 1974. The American Heartworm Society aims to further scientific progress in the study of heartworm disease, inform the membership of new developments and encourage and help promote effective procedures for the diagnosis, treatment and prevention of heartworm disease.


For the American Heartworm Society
Sue O'Brien, 612-305-6116

Release Summary

The American Heartworm Society (AHS) has announced the findings of a nationwide Heartworm Incidence Survey. This survey was based on 3.5 million heartworm tests conducted by veterinarians in 2013.


For the American Heartworm Society
Sue O'Brien, 612-305-6116