Survey of heartworm prevention practices among members of a national hunting dog club.

Surveillance data indicate that failures have been reported for virtually all heartworm prevention product categories. Resistance of third and fourth stage larvae of Dirofilaria immitis to macrocyclic lactones, lack of compliance, other unknown factors, or a combination of these reasons may be the cause of failure. A survey of members of a national hunting dog club was conducted to identify practices used to prevent canine heartworm infections. Questionnaires were completed by 708 dog owners. Year-round administration of heartworm preventive medication was reported by 208 (88%) respondents residing north of the 37th parallel. Dosing was based on the estimated weight of the dog by 54 (7%) respondents, 389 (55%) did not record the date prophylaxis was administered, and 89 (13%) observed the dogs spit out pills. Heartworm testing at least once per year was done by 556 (79%) respondents and test dates were spread throughout the year. Only 448 (64%) respondents tested newly acquired dogs for heartworm. These findings suggest that veterinarians should place a greater emphasis on the frequency and timing of heartworm diagnostic tests, the importance of weighing dogs, duration of administration, recording the date monthly heartworm prophylaxis is given, and observing dogs to ensure that oral medication is retained.