From Biology-Online Dictionary | Biology-Online Dictionary

Lo --> lo dose

(Science: pharmacology) The limes nul dose of diphtheria toxin, i.e., the largest amount of toxin that, when mixed with one unit of antitoxin and injected subcutaneously into a 250-g guinea pig, yields no recognizable reaction in the average of a series; actually, the Lod. Is usually recorded as the one that causes a barely perceptible local oedema at the site of inoculation.