A case of "reversed cannibalism": the piglets damaging the sow.

Sows introduced to a new housing system containing farrowing pens with slatted floor showed increased occurrence of lesions of the vulvar region, caused by the piglets during the later stages of the lactation period. An investigation was undertaken in which the activity of the piglets, particularly rooting and investigatory behavior, was examined and compared to that of piglets kept on straw. Although the occurrence of vulvar lesions disappeared spontaneously before the conduction of the investigation, the results revealed that piglets on slatted floor spent significantly more time chewing on inappropriate objects such as other group members or the vulva of the sow, whereas the rooting and investigatory behavior of piglets raised on straw was almost exclusively directed towards the straw. The results confirm previous observations that piglets living in a relatively poor environment show a greater tendency to direct their activity towards inappropriate objects. If the housing system is otherwise healthy, the change in behavioral activity remains insignificant. If, however, other minor disturbances occur in the system, in the present case clinically insignificant lesions on the vulva of the sow caused by the new slatted floor, aggravation of the lesions can occur due to this change in piglet activity.