Blood sample collection from experimental animals must be less stressful and painful. Blood collection from tail vein will be appropriate for ELISA. Before collecting blood, local anesthetic cream must be applied on the surface of the tail 30 mins before the procedure. If the vein is not visible the tail can be dipped in warm water at around 42 degree C for about 20 secs to dilate the blood vessel . Use 25G needle for blood collection.