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November 2016

Pig: Oedema disease (E. coli)

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History:

Weaner pig from a commercial intensified piggery presented for necropsy to the Western Cape Provincial Veterinary Laboratory (South Africa).  The pig showed acute onset of nervous signs which included paddling and convulsions.

Diagnosis:

Oedema disease (E. coli)

Description:

Marked oedema of the mesentery of the spiral colon

Comments:

Oedema disease is due to a Shiga-toxin producing E. coli and tends to occur a few weeks post weaning. The Shiga toxin induces a degenerative angiopathy with lesions most commonly in the spinal cord, cerebellum, eyelid and colon. The resulting oedema tends to be of low protein content with small numbers of erythrocytes and leucocytes. While the endothelium remains often intact, lesions include perivascular haemorrhage, smooth muscle necrosis and hyaline degeneration (fibrinoid necrosis) of the small arteries and arterioles. Focal encephalomalacia is also a feature of this disease.

Picture by: Dr Sophette Gers Dipl ACVP, Charles River Laboratories, Edinburgh

Authored by: Dr Sophette Gers Dipl ACVP, Charles River Laboratories, Edinburgh and Dr Johanna Baily Dipl ECVP, Institute of Aquaculture, University of Stirling