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In the News

The American Heartworm Society is the leading resource on heartworm disease, and our mission is to lead the veterinary profession and the public in the understanding of this serious disease. Every year, hundreds of stories are written on the diagnosis, prevention and treatment of heartworm, as well as on the plight of affected pets. These stories are an important way of reaching both veterinary professionals and pet owners with information they need to know about heartworm disease.

The American Heartworm Society is led by a board of directors comprised of veterinarians and specialists in the fields of veterinary parasitology and internalmedicine. As leaders in the fight against heartworm disease, they are available as resources and authors of related stories.

Members of the media are encouraged to contact the American Heartworm Society for information, visuals and interviews about heartworm disease. Please contact Sue O’Brien at [email protected] or call 319-231-6129. All other inquiries, please email: [email protected]



News & Alerts

Heartworm prevalent in South, expanding in other hot spots

By Greg Cima

Heartworm disease became more common in hot spots across the U.S. and remained prevalent in the Southeast, Gulf Coast, and lower Mississippi Valley.

Dr. Chris Duke, president of the American Heartworm Society, said the organization’s 2019 survey showed rising numbers of infections with Dirofilaria immitis in Boston, Chicago, Las Vegas, and Minneapolis, as well as in smaller cities such as Durant, Oklahoma, and Redding, California.

Prevention Amid Uncertainty

Veterinarians are concerned that the limitations of COVD-19 has placed on veterinary services could lead to a decline in preventive health care for pets by Graham Garrison

Pandemic or no, now is not the time for the veterinary community to take its collective eye off the importance of heartworm prevention.  That was the message of the American Heartworm Society (AHS) this spring as it announced the results of the 2019 AHS Heartworm Incidence Survey and unveiled a new incidence map drawn from the data of nearly 6,000 U.S. veterinary practices and shelters last year. 


Laying the groundwork for a canine heartworm vaccine

U.K. researchers are looking to determine whether the proteins that allow filarial parasites to establish infections will have similar protective effects in dogs.

Prevention has always been key to fighting heartworm disease in dogs, but few preventive drug options are available and resistance to available medications continues to grow. But a new study by Morris Animal Foundation–funded researchers at the University of Liverpool may unlock the solution veterinarians and pet owners need.

The other heartworm patient

Brian Calabro, DVM

When it comes to heartworms, cats may be overlooked but they’re certainly not immune. Here’s what you need to know about feline heartworm disease.

As summer arrives and temperatures rise, conversations and quarterly promotions in veterinary clinics shift once again to preventing a difficult and deadly disease. And while dog owners are usually familiar with heartworm disease and the importance of prevention, cat owners may be unaware that the disease can affect their pet at all.

The promise of heartworm prevention: An expert Q&A

Heartworm disease prevention and annual testing are a must for dogs and cats across the United States, says Dr. Stephen Jones. Here’s why.

Stephen Jones, DVM, knows a thing or two about heartworms. A general practitioner and partner at Lakeside Animal Hospital in Moncks Corner, South Carolina, Dr. Jones has treated thousands of heartworm infections in pets over the years and served on the board of the American Heartworm Society for more than a decade.

During a lecture at the 2020 Western Veterinary Conference, Dr. Jones noted that despite the fact that Dirofilaria immitis is increasingly found in both endemic and non-endemic areas across the U.S., questions remain about the need for heartworm disease prevention. He set out to answer those questions.

Feline heartworm disease: A diagnostic dilemma

When using antigen and antibody tests, veterinarians need to be aware of their shortcomings

By Tom Nelson, DVM

Heartworm disease is an elusive diagnosis in feline patients. As such, a thorough understanding of the pathogenesis of feline heartworm disease (FHWD) is needed to interpret test results.

How heartworm disease differs in cats and dogs

Cats become infected with heartworms in much the same way as dogs. However, while cats are susceptible hosts, they differ significantly from dogs in the number of infective heartworm larvae that survive to adulthood.

AHS Announces Findings of 2019 Heartworm Incidence Survey

New incidence map shows nationwide cases, confirming need for improved prevention

Wilmington, DE (April 20, 2020)— The American Heartworm Society (AHS) announced the results of the 2019 AHS Heartworm Incidence Survey and unveiled a new heartworm incidencemap drawn from the data of nearly 6,000 U.S. veterinary practices and shelters last year. The conclusion: in spite of the challenges of the current pandemic, 2020 is no time for veterinary practitioners to deemphasize the importance of heartworm prevention.

Mississippi and Louisiana lead the country in heartworm infection rates
No state in the U.S. was heartworm-free in 2019, according to the AHS survey, which determined that the top five states in heartworm incidence were Mississippi, Louisiana, South Carolina, Arkansas and Alabama—all states that have been in the top tier since the AHS began tracking incidence data in 2001. In Mississippi, almost 10 percent of dogs tested for heartworms were heartworm-positive in 2019; in Louisiana, just under 8 percent of dogs tested were positive.

Rounding out the top ten states were Texas, Tennessee, Georgia, North Carolina and Oklahoma. Texas and Tennessee both dropped out of the top 5 ranking between 2016 and 2019, with Alabama and South Carolina moving up. Florida, meanwhile, fell off the top-10 list and was replaced by Oklahoma.

“When veterinarians compare the 2016 heartworm incidence map to the 2019 map, it’s clear that the big picture hasn’t changed,” said AHS president Chris Duke, DVM. “The Southeast remains a hotbed for heartworm infection, but states in the Northeast, Midwest and West have continued to see many cases as well.”

Dr. Duke noted that incidence trends typically vary from year to year due to factors such as weather conditions. “Droughts can lead to declines in infections, while weather events such as hurricanes can trigger incidence spikes as a result of exponential growth in mosquito populations,” he noted. “Meanwhile, the movement of pets from heartworm-endemic areas of the country to less-endemic areas can be problematic if guidelines on transport of heartworm-positive animals are not followed.”

AHS survey cites insights behind the numbers
The AHS Heartworm Incidence Survey is conducted every three years, using data from animals tested over the previous 12 months. The 2019 survey reflected data from more than 5.5 million heartworm tests conducted over the course of a year.

Meanwhile, the survey polled veterinarians on trends noted in the previous three years. Findings from that survey included:

  • Eleven percent of veterinary practices and shelters surveyed reported seeing no heartworm cases, compared to approximately 13 percent three years ago.
  • When asked whether they perceived the trend of heartworm incidence to be up or down over the previous three years, 26 percent of veterinarians saw an upward trend, while 16 percent noted a downward trend and 57 percent of practices and shelters saw no change.
  • Respondents who reported an upward trend were most likely to cite “an influx of heartworm-positive patients into their practice area and “poor compliance” (pet owners failing to administer heartworm preventives year-round and/or skipping doses).
  • Respondents who noted decreases in heartworm incidence cited “improved preventive compliance among users” and “more owners giving heartworm preventives” as the leading reasons.
  • 82 percent of veterinarians surveyed stated that they follow the AHS guidelines on heartworm prevention, testing and treatment.

COVID-19 crisis punctuates need for heartworm vigilance
While the COVID-19 crisis has temporarily limited the ability of many veterinary practices to conduct routine patient health screenings, Dr. Duke stressed that a temporary delay in heartworm testing in 2020 should not lead to lapses in heartworm preventive administration.

“The need for heartworm prevention is more important than ever. Prevention continues to be one of the most important recommendations veterinary practitioners can recommend for patient care, and avoiding gaps in year-round prevention is essential,” Dr. Duke concluded.

Veterinarians seeking guidance on adapting protocols for heartworm prevention, testing and treatment during the COVID-19 crisis can access the AHS’recommendationson heartwormsociety.org.

About the AHS
Founded during the Heartworm Symposium of 1974, the American Heartworm Society (AHS) aims to further scientific progress in the study of heartworm disease, inform the membership of new developments and encourage and help promote effective produces for the prevention, diagnosis and treatment of heartworm disease.

American Heartworm Society Recommendations during COVID-19

Posted by  in Animal SafetyBlogPet Health


American Heartworm Society provides guidance on heartworm protocols during COVID-19 crisis

WILMINGTON, DELAWARE—The COVID-19 crisis has created unprecedented disruptions in veterinary practices and animal shelters, making it challenging for many professionals to deliver wellness care, as well as certain medical treatments, to patients. As veterinary practices and animal shelters strive to provide the best possible care for their patients, questions frequently arise about heartworm prevention, testing and treatment.

American Heartworm Society provides new guidance on heartworm protocols during the pandemic

While telemedicine is proving a lifeline for many hospitals during the current crisis, it doesn’t allow for routine heartworm testing and the administration of certain medications.

To address these issues, the American Heartworm Society (AHS) issued new recommendations to help hospitals and shelters better manage heartworm treatment at a time when many have cancelled routine wellness visits, or, worse, closed their doors for the short term.

NEWStat reached out to American Heartworm Society President Chris Duke, DVM, to find out more about the recommendations.

AHS has published recommendations for how animal health professionals can continue to protect pets from heartworms

Conditions under which a veterinarian can delay annual heartworm tests during the COVID crisis is just one of the topics covered in new recommendations released by the American Heartworm Society (AHS).

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