Vector Laboratories secondary antibodies are purified by affinity chromatography, and cross-reactivities that are likely to interfere with specific labeling are removed by solid phase adsorption techniques. This pan-specific, biotinylated universal secondary antibody is specially formulated to recognize IgG (H+L) primary antibodies from mouse, rabbit, or goat. The antibodies are made in horse, and provide the same high sensitivity and low background as that obtained with our species-specific biotinylated anti-mouse IgG (H+L), biotinylated anti-rabbit IgG (H+L), or biotinylated anti-goat IgG (H+L). Use of this pan-specific secondary antibody provides added convenience and is adaptable to automated instrument staining. Biotinylated Universal Pan-Specific Horse Anti-Mouse/Rabbit/Goat IgG (H+L) is supplied as 2.2 ml of solution. With some exceptions the recommended dilution for most applications is 1:20.