The knowledge and behaviors of a group of dog owners, trainers, and kennel owners about heartworm prevention in dogs were evaluated in this online study. A total of 364 responses were analyzed. Although most respondents (98%) knew that mosquitoes transmit heartworm, 10% thought there were other methods of transmission as well. About equal proportions believed it is more important to give heartworm preventive for 1 month prior to heartworm transmission season than 1 month after (46% and 45%, respectively). Respondents felt the most important drawbacks to giving heartworm preventive were that dogs get heartworm anyway (41%), the cost (33%), and owners remembering to administer it each month (26%). Almost half (49%) did not realize that cats could get heartworm disease. Many respondents (34%) believed that the drugs used for heartworm prophylaxis also killed adult heartworms. More than 40% believed that heartworm preventives could be delayed in puppies until the start of heartworm transmission season or until the puppy was 3 months of age if it was born during the transmission season. If these puppies have a heartworm-positive result a year later, it might be attributed to product failure rather than to faulty timing. The survey concluded that dog owners lack confidence in the accuracy of heartworm tests, the efficacy of preventives, and the effectiveness of treatment to eliminate adult heartworms from infected dogs.

Commentary: It is estimated that more than 1 million dogs are infected with heartworm in the U.S. The results of this survey indicate that we still need to spend time educating our clients about heartworm disease. April is Heartworm Awareness Month, so this is a good time to get the word out: the American Heartworm Society ( has resources for both veterinarians and pet owners.—Patricia Thomblison, DVM, MS

Attributes, knowledge, beliefs, and behaviors relating to prevention of heartworm in dogs among members of a national hunting dog club. Rohrbach B, Lutzy A, Patton S. Vet PARASITOL doi:10.1016/j.vetpar.2011.01.017.


Read Clinician's Update

(supplement, February 2011) for more about preventing heartworm disease. Available at