The condition is actually a combination of two different changes in the back of affected pigs. The medical names for the changes are lordosis and kyphosis. The exact cause of the conditions is not known, but we do know several things about them. Neither is inherited nor present at birth. Most afflicted animals are eight to 16 weeks old, but the condition can develop at any time between three weeks and 15 months of age.
Occurrences are often in the fastest growing pigs.
Males might be more frequently affected than females. Occurrence is sporadic, but may affect up to 4 per cent in a unit and thus become economically significant. Occurs in intensive, confinement-rearing units with little or no bedding. Slowing the rate of growth by reducing the level of feeding might reduce the effects of the condition and even help in recovery in very severe cases. Linked to management and environmental factors associated with intensively housed, rapidly growing, genetically improved pigs.