The older story went like this: the Komodo dragon's mouth harboured such a foul bacterial culture that a bitten buffalo would die of sepsis days later, and the dragon merely followed it. The idea rested on oral swabs taken from captive animals fed on carcass meat, and on the absence of any known venom apparatus in monitor lizards.
Magnetic resonance imaging of a preserved head revealed paired mandibular glands with multiple compartments and ducts opening between the teeth. Extracted secretions contained proteins that reduce blood pressure and interfere with clotting. The bite mechanism is not a hypodermic injection; the serrated teeth open long lacerations and the secretion enters as the jaws pull.
Surveys of wild dragons found oral bacteria broadly typical of what a carnivore picks up from its prey, rather than a uniquely cultivated arsenal. Venom explains the persistent bleeding and shock seen in bitten prey better than sepsis does, though how much of the kill is owed to venom versus straightforward trauma from a very large lizard remains argued.