Why heartworm prevention messaging is becoming more urgent: full analysis
Communicating the value of heartworm prevention is becoming more urgent as heartworm risk expands beyond the regions many pet parents still think of as the traditional danger zones. In a dvm360 interview published April 29, 2026, Marisa Ames, DVM, DACVIM, president of the American Heartworm Society, said practices should prepare the entire veterinary team, not just veterinarians, to answer questions about preventives, explain why year-round use is recommended, and push back on myths about indoor pets, cold climates, and “seasonal” risk. (dvm360.com)
The timing matters. Earlier this spring, AHS released its latest heartworm incidence map, based on heartworm antigen testing data collected during 2025 and surveyed in early 2026. The organization said cases continue to cluster in Gulf Coast and southeastern states, but the map also identified new and growing hot spots outside those historic centers, with Texas leading the nation in incidence. AAHA’s coverage of the map highlighted increasing infection density in places such as East Texas, the Florida Panhandle, southwest Florida, the central Carolinas, and southern Illinois. (heartwormsociety.org)
Against that backdrop, Ames’ core message was straightforward: the recommendation itself hasn’t changed. AHS has recommended year-round, nationwide prevention since 2010, and its current guidelines remain living documents updated with new science and expert review. In the dvm360 discussion, Ames said teams should be ready to explain that it’s difficult to predict mosquito seasonality, that year-round administration may improve adherence by avoiding stop-start routines, and that indoor-only status doesn’t eliminate exposure. She also pointed to overwintering mosquitoes and protected environments such as barns and urban microclimates as reasons risk can persist longer than pet parents assume. (aaha.org)
Other parasite experts are broadly aligned. CAPC states that all dogs, regardless of lifestyle, should receive year-round heartworm prevention, and it extends the same advice to cats. CAPC also notes that 25% to 30% of heartworm-infected cats in cited studies were described by their pet parents as strictly indoor, a useful point for teams trying to counter one of the most common objections in the exam room. (capcvet.org)
The compliance challenge is well established, and it helps explain why communication keeps coming up in expert guidance. In AHS educational materials, poor compliance, either not giving preventives or not giving them on time, is cited by veterinarians as a major reason incidence rises. Another AHS resource advises discussing heartworm prevention at every visit and explicitly comparing the lower cost of prevention with the higher cost and burden of treatment. (heartwormsociety.org)
Published research adds more weight to that argument. A 2021 pharmacoeconomic analysis in Frontiers in Veterinary Science said lack of compliance is believed to be the most common explanation for dogs developing adult heartworm infections and cited record-review data showing insufficient preventive purchases in 81% of heartworm cases examined. A newer retrospective analysis reported that average annual coverage with monthly preventives was 7.3 months, not 12, and found dogs with no preventive purchases in the prior six to 24 months were 6.7 times more likely to test positive than dogs with lapses in purchases. (frontiersin.org)
Why it matters: For veterinary professionals, this is a reminder that heartworm prevention is not just a prescribing decision. It’s a communication workflow. If the front desk, technicians, assistants, and doctors all deliver the same clear message on year-round prevention, annual testing, and realistic mosquito exposure, practices may have a better chance of closing the gap between recommendation and real-world adherence. That matters clinically, because expanding geographic risk and inconsistent dosing can turn a preventable disease into a chronic cardiopulmonary problem with lasting consequences. (dvm360.com)
What to watch: The next step is likely less about new guidance than about implementation: how practices use the 2026 incidence map, AHS client tools, and team training to personalize risk conversations, address cost and safety concerns early, and make year-round prevention feel routine rather than optional. (heartwormsociety.org)