Heartworm preventive efficacy study shows surprising results
Historically, heartworm disease has been effectively prevented
in dogs by using available preventives. However, recent research
indicates that some field isolates and laboratory strains of
Dirofilaria immitis may not be fully susceptible to preventive
medications.1-3 The number of heartworm positive dogs has
increased in certain areas of the central United States, namely
the Mississippi Valley and Delta regions, despite compliant use
of preventives. And other variables, such as testing strategy
changes and increased mosquito vectors, have been ruled out as
potential explanations. The concern is that a subpopulation of
heartworms in these areas has developed resistance to heartworm
preventive medications. Research conducted at Auburn
University’s College of Veterinary Medicine and in collaboration
with others suggests that both biological and genetic changes
have occurred in heartworms in at least some infected dogs. Not
only are there field isolates