IPVS - PWCS Remains a Mystery

CANADA - Two papers presented at the International Pig Veterinary Society Congress (IPVS) have shed a little more light on Postweaning Wasting/Catabolic Syndrome (PWCS) but the condition remains a mystery, writes Jackie Linden from the Congress in Vancouver.
calendar icon 21 July 2010
clock icon 3 minute read

Reports of a new condition, called Postweaning Wasting/Catabolic Syndrome (PWCS) emerged in Canada in 2008. It appeared to be an emerging condition characterised by raised mortality in the nursery. Affected pigs, weaned in good body condition, develop anorexia and most become severely emaciated and die within three weeks of weaning. Mortality rates are reported to rise and fall but they can reach 10 per cent in peak months.

At the IPVS 2010 Congress, Dr Yanyun Huang reported in two papers work carried out by himself and colleagues at the University of Saskatoon on the pathological features of the syndrome and the search to identify the cause(s).

On the pathological changes, Dr Huang reported that the results indicate the principle lesions associated with PWCS are atrophy of the thymus and small intestine villi. He also noted that apparently healthy pigs from the affected herd also suffered villous atrophy, indicating that they may have a subclinical form of the disease or suffering from the early stages or that villous atrophy is a factor pre-disposing these pigs to disease. Dr Huang proposed that villous atrophy may be an indirect result of prolonged anorexia as apparently healthy pigs from the affected herd had no sign of thymus atrophy.

Pigs with PWCS symptoms also showed more colitis than apparently healthy pigs form the farm.

In his second paper, Dr Huang examined the organs of a number of pigs from the PWCS-affected farm for a range of common porcine pathogens. He found no sign of the viruses causing PRRS, influenza, TGE or rotavirus, nor the bacteria, Helicobacter or Campylobacter. The farm regularly vaccinates pigs against PCV so Dr Huang rules out this virus as the cause.

He did highlight that calicivirus was highly prevalent in the intestine of the pigs from the affected farm although it has not previously been reported to cause disease in pigs and calicivirus DNA was found in apparently healthy pigs too.

Dr Huang and his colleagues are continuing their efforts to identify the cause of PWCS, which still remains largely a mystery just now.


Harding J., Y. Huang and H. Gauvreau. 2010. Postweaning Wasting/Catabolic Syndrome (PWCS): pathological features.
Harding J., Y. Huang and H. Gauvreau. 2010. Postweaning Wasting/Catabolic Syndrome (PWCS): the initial diagnostic investigations.
Both in Proceedings of the 21st IPVS Congress, Vancouver, Canada, 18-21 July 2010.

Further Reading

- You can view our previous article on PWCS by clicking here.
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