(630) There are usually none because the pig is found dead but the abdomen is grossly distended.

Diagnosis

This is the most common cause of sudden death in the growing pig and it is usually one of the best pigs in the group. The carcase is fresh the pig is very pale and the abdomen is very distended. Post-mortem examination shows the small and large intestines heavily congested and full of blood. The intestinal tract in the pig is suspended from a common point and this makes it liable to rotate and finally twist.

Management control and prevention

• Deaths are usually sporadic although they can be of significance where, for example, whey is being fed and bloat occurs.
• Over-feeding and abnormal fermentation of the contents of both the small and large intestine result in gas formation, increased pressure and a twist.
• Mortality in weaned and growing pigs should normally be less than 3% and up to a third of this may be caused by torsion. If it reaches 1% or more the dietary components should be examined closely to see if there are starch based ingredients that might cause excessive fermentation. In such cases increasing the level of the growth promoter (if allowed) or adding 100g/tonne of penicillin, OTC or tylosin will reduce the bacterial multiplication.
• If torsion's are consistent causes of death collect information about each one that includes weight, age, sex, house, stocking density, environmental temperatures and feed changes. A study of this may give guidance as to contributing causes.