• Expertise article
• McDowell et al.

Swine disease elimination programs for Mycoplasma hyopneumoniae are commonly applied in the North American swine industry and may include the aerosolization of medium containing lung tissue to achieve population exposure prior to start.

• 10 minutes
• Expertise article
• T Kusk, A Priebe, PH Rathkjen, K Havn

PRRSV can be transmitted through aerosols. It travel associated with particles and has been detected in air as far as 9.1 km from swine herds. Growing pigs represents the absolute majority of PRRSV infected pigs in an area. Growing pigs have a longer duration of viremia and shed PRRSV for a longer period than the adult breeding stock the control of PRRSV circulation in growing pig populations is essential. This can be achieved through a combination of correct biosecurity, pigflow, management and immunization.

• Expertise article
• R Philips, G Haiwick, D Whiteman, J Hermann, B Fergen

The objective of this study was to evaluate the efficacy of Ingelvac PRRS MLV, Prevacent PRRS and a novel experimental PRRSV MLV vaccine in a pig respiratory challenge model.

Ingelvac PRRS MLV group demonstrated a significant improvement in ADWG and reduction in the level of viremia compared to both the Prevacent PRRS and non-vaccinated control groups during the post-challenge period.

• 3 minutes
• Expertise article

Three-week-old cesarean-derived colostrum-deprived (CD/CD) pigs were inoculated with porcine circovirus type 2 (PCV2, n 19), porcine reproductive and respiratory syndrome virus (PRRSV, n 13), concurrent PCV2 and PRRSV (PCV2/PRRSV, n 17), or a sham inoculum (n 12) to compare the independent and combined effects of these agents. Necropsies were performed at 7, 10, 14, 21, 35, and 49 days postinoculation (dpi) or when pigs became moribund. By 10 dpi, PCV2/PRRSV-inoculated pigs had severe dyspnea, lethargy, and occasional icterus; after 10 dpi, mortality in this group was 10/11 (91%), and all PCV2/ PRRSV-inoculated pigs were dead by 20 dpi. PCV2-inoculated pigs developed lethargy and sporadic icterus, and 8/19 (42%) developed exudative epidermitis; mortality was 5/19 (26%). PRRSV-inoculated pigs developed dyspnea and mild lethargy that resolved by 28 dpi. Microscopic lesions consistent with postweaning multisystemic wasting syndrome (PMWS) were present in both PCV2- and PCV2/PRRSV-inoculated pigs and included lymphoid depletion, necrotizing hepatitis, mild necrotizing bronchiolitis, and infiltrates of macrophages that occasionally contained basophilic intracytoplasmic inclusion bodies in lymphoid and other tissues. PCV2/ PRRSV-inoculated pigs also had severe proliferative interstitial pneumonia and more consistent hepatic lesions. The most severe lesions contained the greatest number of PCV2 antigen–containing cells. PRRSV-inoculated pigs had moderate proliferative interstitial pneumonia but did not develop bronchiolar or hepatic lesions or lymphoid depletion. All groups remained seronegative to porcine parvovirus. The results indicate that 1) PCV2 coinfection increases the severity of PRRSV-induced interstitial pneumonia in CD/CD pigs and 2) PCV2 but not PRRSV induces the lymphoid depletion, granulomatous inflammation, and necrotizing hepatitis characteristic of PMWS.