Which heartworm testing method is more sensitive in cats compared to dogs?

Antibody testing is particularly significant in the context of diagnosing heartworm disease in cats compared to dogs due to differences in the host's immune response to the parasite. In cats, the immune response to infection with Dirofilaria immitis often leads to the production of antibodies, which can be detected through this testing method even when the actual adult heartworms are present in smaller numbers or when they are immature.

Cats tend to have a lower worm burden when infected, and antigen tests, which rely on detecting specific proteins produced by adult female heartworms, may not be as effective given the fewer adult females present. Furthermore, many infected cats can have a transient or incomplete infection wherein they do not harbor enough adult female worms to trigger a positive antigen test, making antibody testing a more sensitive method in this species.

The direct blood smear method and radiographic assessments are generally less reliable for detecting heartworm infection as they do not provide the same level of specificity or sensitivity regarding the immune response. Thus, antibody testing stands out as the preferred method in cats, enhancing the likelihood of early and accurate diagnosis of heartworm disease.