Until the 1990s, defining and maintaining a High Health (HH) Status was relatively straightforward. Organisations such as the Pig Health Control Association were able to define and identify certain diseases such as Enzootic Pneumonia (EP), (Mycoplasma hyopneumoniae) or Swine Dysentery (SD) (Brachyspira hyodysenteriae,) and then establish, by hysterectomy or medicated early weaning (MEW), “clean” units which became the Nucleus units of the breeding companies. These produced “clean” pigs to populate Multiplication units that eventually passed on HH breeding stock to commercial customers. Relatively straightforward laboratory and abattoir monitoring could give reasonable, repeatable assurance to customers. Good biosecurity maintained this HH status and many HH commercial units were established by destocking, cleaning, and restocking with HH pigs from these breeding companies. Then the wheels started to fall off!