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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

Help Stop Heartworm Travel Plans

The American Heartworm Society announces new “best practices” to help stop heartworm transmission via transported dogs.

(Photo courtesy of the ASPCA)

Transporting and relocating dogs is an increasingly common practice.

Whether the situation is an owned pet accompanying emigrating or traveling caretakers, the relocation of homeless animals for adoption, or the movement of dogs for competition, exhibition, research or sale, this process carries the risk of spreading infectious diseases.This includes the transmission of Dirofilaria immitis when infected dogs have become microfilaremic.

The following practices will minimize the risk of heartworm transmission associated with the transportation and relocation of dogs ( pdfFull Story): 

1. Test all dogs greater than 6 months of age for microfilariae (Mf) and heartworm antigen (Ag) prior to relocation.

a. If testing is not possible, assume transmission is possible and proceed to Step 3b.

2. If dogs test positive for microfilariae or antigen, reconsider relocation at this time and begin treatment in accordance with the American Heartworm Society (AHS) Guidelines.

a. Dogs with clinical signs attributed to heartworm infection should not be transported.

b. Dogs that have been treated with melarsomine dihydrochloride should not be transported for at least 4 weeks after an injection to minimize stress and physical exertion that accompany the relocation process.

3. If dogs test positive and relocation cannot be postponed, clinical decisions should be based on the dog’s heartworm status.

a. If Mf-, Ag+:

i. Administer an approved macrocyclic lactone product. This should prevent the prepatent dog from becoming microfilaria positive.1

ii. Begin doxycycline therapy.
A 4-week course of doxycycline should prevent the pre-patent dog from becoming microfilaria positive.2,3

iii. Repeat Knott’s testing in 7 days; if negative, proceed with relocation. If positive, repeat Knott’s testing in 7 days.
Two negative tests 7 days apart can provide reasonable assurance of a lack of circulating microfilariae and reduced risk of transmission.

b. If Mf+, Ag- or Mf+, Ag+:

i. Apply an approved moxidectin topical product and proceed with relocation.
A single dose of topical moxidectin prior to transport will eliminate most microfilariae.4-6
Administer an approved macrocyclic lactone product along with a topical canine insecticide (containing permethrin + dinotefuran + pyriproxyfen) that is labelled to kill and repel mosquitoes. This will prevent infection of mosquitoes and subsequent transmission of infective larvae during transportation and for 1 month thereafter.7

ii. Begin doxycycline therapy.
Administration of a 4-week course of doxycycline will render microfilariae incapable of normal development to infective larvae in mosquitoes and subsequent development of these larvae in dogs.8,9

Once heartworm-positive dogs have been safely transported, heartworm treatment should be completed according to AHS Guidelines as soon as possible.

4. If dogs test negative for microfilariae and antigen, proceed with relocation.

a. Administer macrocyclic lactone preventive drugs to dogs greater than 6 weeks of age prior to relocation.1

b. Repeat microfilariae and antigen testing in 6 months. If a history of preventive administration is well-documented, repeat testing in 12 months.1

Caring for dogs that undergo relocation is an everyday challenge veterinarians face in today’s mobile society, and one that necessitates the adoption of approaches to mitigate heartworm transmission.

Along with considering the recommendations in this document, veterinarians should ensure that transportation of animals is carried out in accordance with state and/or federal transportation regulations, as well as professional guidelines.10,11

In the case of organized homeless animal relocation programs, veterinarians should work with both source and destination organizations to establish protocols for minimizing transmission of infectious diseases, including heartworm disease.

SKO Transport Guidelines Algorithm

1. American Heartworm Society. Current Canine Guidelines for the Prevention, Management, and Diagnosis of Heartworm Infectionin Dogs. Available online here
2. Hoerauf A, Mand S, Fischer K, et al. Doxycycline as a novel strategy against bancroftian filariasis – depletion of Wolbachia endosymbionts from Wuchereria bancrofti and stop of microfilaria production. Med Microbiol Immunol. 2003; 192:211-216.
3. Rossi MID, Paiva J, Bendas A, et al. Effects of doxycycline on the endosymbiont Wolbachia in Dirofilaria immitis (Leidy, 1856) —Naturally infected dogs. Vet Parasitol. 2010; 174:119-123.
4. Bayer Healthcare LLC. Advantage Multi® Product Label. Available online here
5. Blagburn BL, Dillon AR, Arther RG, et al. Comparative efficacy of four commercially available heartworm preventive products against the MP3 laboratory strain of Dirofilaria immitis. Vet Parasitol. 2011; 176:189-194.
6. McCall JW, Arther R, Davis W, Settje T. Safety and efficacy of 10% imidacloprid + 2.5% moxidectin for the treatment of Dirofilaria immitis circulating microfilariae in experimentally infected dogs. Vet Parasitol. 2014; 206; 5-13.
7. McCall JW, Hodgkins E, Varloud M, et al. Blocking the transmission of heartworm (Dirofilaria immitis) to mosquitoes (Aedes aegypti) by weekly exposure for one month to microfilaremic dogs treated once topically with dinotefuran-permethrin-pyriproxyfen. In Proceedings, 2016 American Heartworm Society Triennial Symposium. Parasites & Vectors, 2017, in press.
8. McCall JW, Genchi C, Kramer L, et al. Heartworm and Wolbachia: therapeutic implications. Vet Parasitol. 2008; 158:204-244.
9. McCall JW, Kramer L, Genchi C, et al. Effects of doxycycline on heartworm embryogenesis, transmission, circulating microfilaria, and adult worms in microfilaremic dogs. Vet Parasitol. 2014; 206(1-2):5-13.
10. American Veterinary Medical Association. Relocation of Dogs and Cats for Adoption: Best Practices. Available online here
11. Association of Shelter Veterinarians. Guidelines for Standards of Care in Animal Shelters. Available online here.

AHS Heartworm Hotline Beyond the Map: The State of Heartworm Incidence in the United States

How many pets in the United States are infected with heartworms? The truth is that no one knows. Because heartworm diagnosis requires one or more blood tests that must be conducted in a veterinary clinic and/or testing laboratory, diagnosis is limited to patients seen in veterinary hospitals and animal shelters. Dogs and cats not seen by veterinarians and/or not tested for heartworms during annual veterinary visits may be infected but go unrecognized.


AHS Heartworm Hotline Turning Up the Heat on Heartworm Diagnosis

Antigen testing for Dirofilaria immitis has been a foundational component of model preventive veterinary care for many years, particularly for dogs. For privately owned pets, the results of such testing guide prevention strategies and, in the event of a positive result, treatment for heartworm disease. In shelter populations, the results are often a key determining factor in the management of a dog throughout its stay in the shelter system, including its likelihood of a live release.

AHS Heartworm Hotline Heartworm Education: It Takes a Team

Heartworm disease is one of the most important diseases threatening companion animals. According to the American Heartworm Society (AHS), disease caused by Dirofilaria immitis has been diagnosed in all 50 states, and, as most veterinarians and veterinary technicians are aware, it can affect both dogs and cats. Veterinary professionals have a wealth of effective, Food and Drug Administration–approved products, including oral, topical, and injectable formulations, that make heartworm disease preventable. One goal of veterinarians and technicians should be to ensure that every pet is protected from heartworm disease for 12 months each year. The key to realizing this goal is effective client education.

Heartworm-Associated Respiratory Disease in Client-Owned Cats

Feline heartworm disease is diagnosed less frequently than its canine counterpart. Several factors likely contribute to this discrepancy, including the inherent resistance of cats to heart worm infection, the limitations of diagnostic testing for cats, and the nonspecific (and frequently absent) clinical signs associated with feline heartworm disease.

AHS Announces Findings of New Heartworm Incidence Survey

Survey of U.S. veterinarians uncovers per-practice increase in heartworm-positive cases

Wilmingon, DE  (April 17, 2017)—While the hotbeds of heartworm disease haven’t changed dramatically in the past three years, the incidence numbers reported by participants in the 2016 American Heartworm Society (AHS) Incidence Survey indicate that the average number of positive cases per veterinary clinic has been inching upwards. The AHS announced its latest survey data, along with unveiling a new heartworm incidence map based on data from veterinary practices and shelters across the country.

New Slideshow on Mosquitoes for Social Media Use

The American Heartworm Society is proud to present  a new slideshow for use on our members' social media pages. This will be the first of several new tools AHS members can leverage now and during heartworm awareness month. Stay tuned for more!

4 Simple Rules to Keep Your Pet Healthy All Year Long (Martha Stewart Living)

One small — but crucial — tip has to do with heartworm medicine.

It's only natural to stop and take stock of your own health at the start of the new year. Here's why — and how — to do the same for your pets. There's certainly no right or wrong time to reassess the care your pet needs to stay heathy and happy. But the beginning of the year — after the hustle and bustle of the holidays, when you're making resolutions to stick to good habits — is an opportune time to give your pet's well-being the attention it needs, too. We've put together a list of the main tasks to keep in mind.


The Back Page: Veterinary Viewpoints The American Heartworm Society Looks Toward the Future An Interview with Dr. Christopher Rehm

Christopher J. Rehm, Sr, DVM, is the incoming president of the American Heartworm Society (AHS). Dr. Rehm graduated from Auburn University College of Veterinary Medicine in 1982 and started Rehm Animal Clinic a year later in Mobile, Alabama. The clinic has grown into four AAHA-certified hospitals in two Alabama counties, employing 13 veterinarians and more than 70 support staff. With a clinic slogan of Caring for pets and people since 1983, Rehm Animal Clinic (rehmclinics.com) has won numerous Best Clinic and readers’ choice awards from local newspapers. In addition to practicing veterinary medicine, Dr. Rehm has written a syndicated pet column and hosted live public service spots and serves as a speaker at veterinary meetings.

Complexity of Heartworm Prevention, Diagnosis and Treatment Detailed at 15th Triennial Heartworm Symposium

American Heartworm Society also announces new officers, board members

NEW ORLEANS (September 22, 2016) — Changes in climate, heartworm vectors, diagnostic challenges, prevention practices and treatment protocols all were cited during during the 2016 American Heartworm Society (AHS) Triennial Symposium as reasons why the persistence of heartworm disease continues to confound veterinarians, researchers and pharmaceutical companies.

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