By Dr Andrew Tucker, Charles Street Veterinary Consultancy
Oedema disease is caused by enteric infection with E.coli strains which produce a toxin that is absorbed to affect the arterial walls. The damage to the arterial walls results in tissue oedema and central nervous system damage. The disease may affect ten to 30% of recently weaned pigs with up to 100% mortality in the affected animals. Oedema disease is not of public health importance.How do you know if it’s on your farm?
Oedema disease usually occurs within ten days of weaning and often affects the better pigs in the group. The first signs the pigs may show is diarrhoea, however, the most common clinical signs are facial oedema, nervous signs and sudden death. The facial oedema is often most obvious in the eyelids. Pigs will often appear dull and the disease can lead to incoordination and finally recumbency in protracted cases. Affected animals may recover completely except for a check in growth.
Dead animals are normally in good condition with full stomachs. On close inspection oedema can usually be found in the eyelids and certain parts of the gastrointestinal system. The clinical signs, post mortem and histopathology findings are distinctive and the disease can be confirmed by isolating the specific types of E.coli involved.
How do you treat or prevent it?
Treatment involves antimicrobial therapy. This should be done according to the results of antimicrobial sensitivity tests. Reduction in feed intake or increased inclusion of bran in the diet can reduce the E.coli load in the remainder of the group.
Control can be achieved by management alone. The key points that can have an effect are applying very strict hygiene and biosecurity practices post weaning and providing an ideal environment. Further steps that minimise the problem are increasing creep feed pre weaning, reducing the protein in high protein rations and including certain feed additives.
No vaccine is commercially available yet and although some pigs are genetically resistant to this disease it is currently not possible to select resistant pigs on a commercial scale. There have been some success stories in Denmark where herds have remained uninfected after depop-repop projects.