Savaging piglets (cannibalism, puerperal psychosis)

Occurrence: Worldwide.
Age affected: Gilts.
Causes: Stress, pain; mismanagement of farrowing; genetic.
Effects: Fear, excitement, piglet injury / death.

Causes

Savaging is most common in gilts with their first litters and is often associated with nervousness or apprehension in the gilt before farrowing. It may occur in some families or breeds and may be associated with fear of the new farrowing environment, especially when the animals have been loose housed prior to crating. The hormonal changes associated with farrowing may contribute to the behaviour.

In some cases, a sick sow may start attacking her piglets or piglets with unclipped teeth may damage the udder and cause pain. Poor relationships with stockpersons may also predispose to savaging as may crating the sow in conditions where the piglets can pass in front of the sow frequently.

Mode of transmission

This condition is not generally transmissible, but where there is a breed or family susceptibility, gilts may behave like their mothers.

Clinical signs

Gilts which savage piglets can often be identified by their nervous appearance and wild eyes. They may be aggressive towards stockpersons and grunt aggressively or swing their heads towards any annoyance. The first two or three piglets of the litter may be seized and bitten or worried or simply be eaten. If the sow remains nervous, the whole litter may be destroyed. This behaviour is normally confined to first litter gilts, but may recur in subsequent litters. Piglets which have been injured may have obvious cuts on head or shoulders and sometimes on the back .These cut and tears dry quickly in the warm farrowing environment and the piglet may recover.

There may be a history of savaging in previous litters, and the record card should be consulted. Sows may be wild and aggressive or fail to settle in a farrowing crate. Savaging may be observed directly during supervision of farrowing or heard as piglets are attacked. Where piglets are killed and left, there are tooth marks on the carcase or triangular tears on the head, shoulders and hindquarters.

Where they are eaten completely, cannibalism can be suspected if the sow is seen to have blood on her face or if a count of piglets born has been carried out and there are animals missing when predators could not be responsible or other workers could not have collected casualties. Post-mortem examination will confirm the presence of crushing injury in life and bleedings into bruised muscle. The condition may have to be distinguished from crushing.

Postmortem lesions

There are usually tooth marks on the carcase or triangular tears on the head, shoulders and hindquarters. Post-mortem examination will confirm the presence of crushing injury in life, indicated by bleeding into bruised muscle. The condition may have to be distinguished from crushing by the sow or damage caused by shutting the animal in a gate.

Treatment and prevention

Piglets should be confined in the creep for 15-20 minutes after birth to stop them walking in front of a newly farrowed sow.  They should be introduced gradually to the sow and allowed to suck. The initial contact should be observed so as to prevent savaging. Azaperone can be injected to tranquilise the sow and reduce her fear. The condition can be prevented by recording incidents and ensuring that sows which have savaged previous litters are closely observed until the litter is safe.

Gilts entering farrowing accommodation should be assessed for signs of nervousness. Newly confined gilts should be given straw and allowed to play with it or eat it. The house should be warm and free from draughts and disturbance should be minimised. The sow’s reaction to the piglets of other sows should be assessed and the piglets to which the sow is exposed rescued if attacked and returned to their mother. As the condition may be familial, consider not retaining the offspring of gilts and sows which savage in the herd and do not use them for breeding.