The malaria technique of thick-n-thin slides is applicible. Also, RBC will settle if an equal volume of 6 % dextran is added. Examination of the buffy coat spun in capillary tubes may be the best way to detect mfs. Two percent formalin or paraldehyde will fix mfs suitably for measurements or other tasks. Immunochemistry is not well developed, or not applied, e. g., acid phosphatase test.. Here, there still is enormous room for improvement and much experimental flexibility. Buffy coat as in QBC of B-D can be developed for several diseases.

ELISA is available for detection of adult D. immitis antigen both before and after mfs are found in blood.

DiroCheck (Symbiotics) and PetCheck (IDEXX) are available as microwell ELISAs. Other rapid tests are: Snap (IDEXX), AbboScreen (Abbot), Solo Step (Heska) and Witness (Symbiotics).

These and other serological tests sometimes produce false negatives just as slide examination may produce a false negative. Therefore such tests should be run WITH microscope tests. Might a blood smear be negative during the day and positive at night ? Does this periodicity correlate with the daily cortisol cycle ? Where are the mfs when they are not swimming in the blood stream ? Another direct approach to diagnosis is demonstration of mfs in the blood using Knott’s popular centrifuge concentration test or a filter test.