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AHS Survey Finds Increase In Heartworm Cases

Q. What did the new AHS survey reveal about heartworm incidence in the U.S.?

A. About 4,500 veterinary practices and shelters from across the U.S. participated in the AHS Incidence Survey in early 2017, with the surveyfocusing on data from the 2016 calendar year. Approximately 24 percent of respondents noted an increase in heartworm incidence since 2013, while 19.8 percent noted a decrease.


Q. What about the distribution of heartworm incidence? Has that changed in the past few years?

A. Heartworm cases are on the rise in the most endemic areas. The states with the highest heartworm incidence continue to be in the Southeast, Mid-South and Mississippi Delta regions. The top five states of Mississippi, Louisiana, Arkansas, Texas and Tennessee have been in the top ten states since we began conducting this survey in 2001. On a brighter note, certain areas of the country—in particular, California, Nevada, Arizona and New Mexico—saw incidence rates drop. The long-term drought in the West may have been a factor; however, recent relief from this drought means that the risk of heartworm transmission may increase in the future.

Q. What advice do you have for veterinarians?

A. We hope practitioners in areas with decreases in heartworm incidence will be inspired to continue their hard work, while veterinarians in areas with higher incidence will redouble their efforts. As the president of an organization devoted to heartworm education and research, I urge veterinarians to use the many free resources on heartwormsociety.org and to follow the AHS guidelines on annual testing and year-round prevention. Working together, we can ensure that the next incidence map paints a less colorful picture.


AHS Survey Findings

  • Heartworm was diagnosed in all 50 states.
  • The average number of heartworm-positive dogs per clinic increased by 21.7 percent.
  • Among veterinarians who noticed an increase in heartworm diagnoses over the past three years, almost half cited failure to give preventives, skipping doses or failing to give preventives year-round as contributing factors. Other factors included weather that contributed to heartworm transmission and the influx of heartworm-positive dogs from areas of the country with high heartworm incidence
  • Among veterinarians who saw a drop in diagnoses since 2013, two-thirds attributed the increased usage of heartworm preventives and improved owner compliance.
  • Three quarters of respondents follow the AHS guidelines on heartworm prevention,diagnosis and treatment


For more information on this and other heartworm topics, visit heartwormsociety.org.


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