Research results from the Royal Veterinary College (RVC) show that environmental stress, related to such factors as high temperatures or crowding, can cause Porcine CircoVirus Associated Disease (PCVAD) symptoms without the influence of secondary infections.
RVC researchers were investigating the previously described, post-weaning multi-systemic wasting syndrome, now known as PCVAD, which can lead to diarrhoea, wasting, respiratory distress and death.
It was originally assumed that the development of PCVAD needed porcine circovirus 2 (PCV2), as a secondary infection, for symptoms to occur. However, the RVC work shows, for the first time, that environmental stress can induce PCVAD symptoms, without any secondary infection being present.
RVC’s conclusion is that PCV2-infected pigs, kept in temperatures above the comfort temperatures, or kept in pens smaller than current minimum guidelines were “more likely to show reduced weight gain and had higher viral loads than those kept in cooler temperatures or larger pens”. The college also said that such “risk factors” can occur in herds in the UK.
RVC project leader, Professor Dirk Werling, added: “We were able to confirm that these risk factors really contribute to the severity of clinical signs under experimental conditions.”
He also said the findings showed clearly that “sub-optimal management will have further impact on economic losses”.