According to the American Heartworm Society (AMS), it is estimated more than one million dogs have heartworm disease. Spread by mosquitoes, heartworms live in the heart and pulmonary arteries of infected dogs and cats. Left untreated, the disease can lead to heart failure, as well as damage to other organs. To mark Heartworm Awareness Month, we asked Claire Walther, DVM, veterinary specialty operations at Zoetis Petcare, for her take on what veterinarians can do to better convey the need for heartworm prevention to pet owners.
1) What is the single biggest misconception among veterinarians regarding heartworm disease?
Biologically, it is how missing one dose of a preventative medication can lead to the development of heartworm disease. We say it to our clients daily, but many of us couldn’t explain why if a client asked.
In my own practice, I struggled with the answer. Here is a 30-second sound bite I’ve used with my clients to help simplify what is a complex discussion.
“Young heartworms are carried by infected mosquitoes, and it only takes one bite to transmit them to your dog.1 Once in your dog, the young heartworms live just underneath the skin for about a month—this is where prevention products kill the heartworms. After a month, the heartworms mature and move into the bloodstream. Once they enter the bloodstream, they are no longer responsive to heartworm preventatives, so it is critical to give continuous prevention to ensure your dog stays protected from this disease.”
2) Which animals are most at risk, whether according to lifestyle or geography or some other factor?
All dogs and cats are at risk for heartworm disease. It has been diagnosed in all 50 states.1 Mosquitoes aren’t outdoor-only and easily enter homes, apartments, doggie daycare facilities, and kennels. We should focus less on teasing out individual lifestyles and more on making a strong recommendation for year-round heartworm disease prevention because pets of all lifestyles and geographies are at risk.
3) If pet owner compliance is an issue, how else can veterinarians ensure their patients are protected?
Pet owner compliance has been historically low and is a key contributing factor to the rise in incidence of heartworm disease. Only one in three dogs receives heartworm disease prevention nationally. Of those, the average doses purchased are 8.6 monthly doses per year, instead of the necessary 12 months.2 Veterinarians can improve pet owner compliance by owning it. An injectable solution with six months of protection against heartworm disease can improve compliance because it is administered in hospitals by trained veterinary staff. From the pet owner’s point of view, it’s nice to have someone take one thing off your plate in this fast-paced world.
4) What question regarding heartworms or heartworm disease prevention is never asked, but is important to answer?
By far, it’s why have we grown complacent as a profession with heartworm disease. Heartworm disease can be fatal. It lives in everyone’s backyard. We all took an oath to protect pets as a part of the family. And heartworm is, arguably, the most important parasite in North America.
1 American Heartworm Society. Guidelines for the Diagnosis, Prevention, and Management of Heartworm (Dirofilaria immitis) Infection in Dogs and Cats. https://www.heartwormsociety.org/veterinary-resources/american-heartworm-society-guidelines. Accessed April 11, 2019.
2 Drake P, Wiseman S. Increasing incidence of Dirofilaria immitis in dogs in USA with focus on the southeast region 2013-2016. Parasites & Vectors. 2018; 11:39. doi: 10.1186/s 13071-018-2631-0.