Research carried out by the British Royal Veterinary College (RVC) has found environmental issues such as stress and overcrowding can lead to PCVAD in pigs, without secondary infections.
PCVAD is a complex group of diseases which causes loss of body condition, visibly enlarged lymph nodes, difficulty in breathing, and sometimes diarrhoea, pale skin, and jaundice. It was believed that PCVAD was a result of Porcine Circo Virus 2 (PCV2), which is a common trait among infected pigs.
However, this is the first time environmental factors have been linked to the group of diseases in pigs, and researchers believe the findings could save the pig industry millions in preventative measures.
Researchers found higher temperatures, crowding, or both, can induce symptoms attributed to PCVAD without any secondary infection from PCV2. Pigs kept in pens smaller than current minimum guidelines and uncomfortable temperatures were found to have reduced weight gain and higher viral loads than pigs in more comfortable conditions.
Professor Dirk Werling, from RVC, who led the project, said: "Within the initial part of this project, we identified specific risk factors on farms that had an impact on disease severity. Now, we were able to confirm that these risk factors really contribute to severity of clinical signs under experimental conditions. These findings clearly show that sub-optimal management will have further impact on economic losses. We are confident that our findings have a really big impact for the pig industry, given the fact that PCV2 is so common.
"These findings clearly indicate that in addition to vaccination against PCV2, changes in the current farming systems can only be achieved in the long term through a more sustainable agricultural approach, which would involve a less stressful rearing of animals for food consumption. As customers’ increasingly prioritise good conditions for livestock, pressure on farmers to produce as cheap and fast as possible might reduce."