WITNESS Lepto detects the primary immune response (immunoglobulin M [IgM] antibodies) which develops within one week of exposure to canine leptospires. WITNESS Lepto was shown to detect four important canine serovars – Canicola, Grippotyphosa, Icterohaemorrhagiae, and Pomona. The WITNESS format is referred to as Rapid ImmunoMigration (RIM™), sometimes referred to as lateral flow or rapid immunochromatography.