Changing Trends and Issues in Canine and Feline Heartworm Infections

Canine and feline heartworm diagnostic, treatment and prevention strategies have changed during the previous decade. We experienced an unprecedented increase in the numbers and kinds of available medications and diagnostic aids, and also in the capabilities of pet owners to acquire information. This can be both beneficial and detrimental in our efforts to establish and maintain effective strategies for controlling heartworm infections. Pet owners have become more aware of the potential dangers of heartworm infections. Also, available treatment and prevention products have become more effective and convenient to use. However, much misinformation is communicated through electronic mail and web sites dealing with heartworm. The activities of newer avermectins and milbemycins against microfilaria and larval heartworms, and activity of some against adult stages of heartworms, add additional possibilities for heartworm control. The same can be said for immunologic tests for in clinic use. Discrepancies between microfilaria tests and antigen or antibody test results can lead to confusion about the actual infection status of pets. In the following, I will discuss some of these issues. My purpose is to draw attention to these issues so that veterinarians can better deal with problems that they create.