PWCS: new pig disease, still many questions

Scientists have revealed pathological results and an initial diagnostic investigation to PWCS, a relatively new postweaning wasting disease occurring in Canada.

Pig Progress Editor Vincent ter Beek reports from IPVS, Vancouver

The results were made public at the 21st edition of the International Pig Veterinary Society (IPVS) Congress, held 18-21 July in Vancouver, BC, Canada.
Yanyung Huang, attached to the University of Saskatchewan, Saskatoon, SK, Canada presented the first research data of the disease, which was done together with Prof Dr John Harding and Henry Gauvreau of Warman Veterinary Services.
Persistent and extensive mortality
Porcine Postweaning Wasting/ Catabolic Syndrome (PWCS) has been reported by veterinarians since 2008, noting “persistent and sometimes extensive nursery mortality associated with anorexia and weight loss in PCV2-vaccinated pigs.” It is suggested that the PWCS is 'likely to be infectious'.
The variety Huang and others studies occurred at an anonymous 100 sow farrow-to-finish unit. Necropsy and histology showed the disease caused thymic atrophy, empty gastro-intestinal tracts and bronchopneumonia.
Huang observed that PWCS always comes with:
·  fundic gastritis
·  atrophic enteritis in the small intestine – the length of the villi is reduced or they are even gone, in the duodenum, the jejunum and the ileum
· colitis
· rhinitis (nasal mucosa)
Ruling out pathogens
Tests, in which Brendan O'Connor of Prairie Diagnostic Services has also been involved, ruled out that the disease was caused by a whole series of plausible bacteria, viruses and parasitic pathogens, including e.g. PRRSV, PCV2 and influenza.
Enteric calicivirus was highly present in several of the infected pigs, but is not known to cause any disease in commercial pigs.
More research therefore needs to be done to determine as to what pathogen(s), known or unknown, may cause the disease.
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