Direct microscopic examination of intracellular parasites on stained blood films is the standard for definitive diagnosis in nearly all settings.

The young trophozoite (or "ring" stage, because of its morphology on stained blood films) grows substantially before undergoing schizogonic division.

Haematology investigation revealed no abnormalities, particularly no elevated eosinophil count, and no microfilariae were seen using stained blood films; the filariasis serology was negative.

Wright's stain is a simpler method, whilst Leishman's is also a simple method which is especially suitable when a stained blood film is required urgently or the routine stain is not available (e.g. at night).

With appropriate laboratory equipment, microscopic examination of differential morphological features of microfilariae in stained blood films can aid diagnosis-in particular the examination of the tail portion, the presence of a sheath, and the size of the cephalic space.

During the acute phase of infection, M. haemofelis can be readily identified on stained blood films however M. haemofelis can disappear and reappear in the peripheral blood throughout the course of infection and can be mistaken for stain precipitate or vice versa.