Association of the presence of influenza A virus and porcine reproductive and respiratory syndrome virus in sow farms with post-weaning mortality.

Influenza A virus (IAV) and porcine reproductive and respiratory syndrome virus (PRRSV) are among the most important pathogens affecting pigs worldwide. Their effect on post-weaning mortality can be substantial and may be potentiated by other concomitant factors. Here, the objective was to evaluate the association between IAV and PRRSV infection at weaning with post-weaning mortality observed in wean-to-finish farms in order to better quantify the full impact of their presence in breeding herds. IAV and PRRSV presence was assessed by real time reverse transcription (RRT)-PCR on oral fluid samples from suckling piglets in nine sow farms. Production data from 177 batches of growing pigs weaned one week before/after IAV and PRRSV testing were analyzed to measure the association between IAV and/or PRRSV test results and mortality recorded for a given batch through the use of Bayesian mixed effects negative binomial multivariable regression model. The model accounted for potential confounders such as flow, date at weaning, days on feed and batch size. A statistically important association between IAV (incidence ratio (IR)=1.18, 95% posterior probability interval 1.15-1.21) and PRRSV (IR=1.41, 95% PPI 1.30-1.52) with post-weaning mortality was detected, with season and number of days on feed also associated. Our results suggest that infection with IAV or PRRSV in the pre-weaning period is associated with an increase in post-weaning mortality. This association should be taken into consideration when measuring the impact of IAV and PRRSV in breeding herds.

Impact of porcine epidemic diarrhea on performance of growing pigs.

The impact of porcine epidemic diarrhea virus (PEDv) infection on the US pork industry has mainly been attributed to the mortality that it causes in suckling piglets, and, consequently, much effort has been invested in the quantification of its effect in sow farms. However, no information on the performance of surviving pigs that were exposed to the PEDv as piglets is available. Here, a retrospective cohort study to evaluate the impact of porcine epidemic diarrhea virus (PEDv) infection on growing pigs' performance, as indicated by mortality, average daily gain (ADG), average daily feed intake (ADFI), and feed conversion ratio (FCR) was performed using production records from weaned pigs in nursery and wean-to-finish sites from sow farms that became PEDv-infected between May 2013 and June 2014. Production records from the first batch of growing pigs weaned in infected flows after the PEDv outbreak ("infected batches") were compared with those from pigs weaned within the previous 14 to 120 days ("control batches"). Performance records from infected and control batches, paired by flow, were compared using non-parametric paired tests. Mortality, ADG and FCR were significantly different in PEDv-positive (infected) compared with PEDv-negative (control) batches, with a mean increase of mortality and FCR of 11% and 0.5, respectively, and a decrease of ADG of 0.16 lb/day. Our results demonstrate a poorer performance of growing pigs weaned after a PEDv outbreak compared with those weaned within the previous 14-120 days, suggesting that in addition to the mortality induced by PEDv in suckling pigs, the disease also impairs the performance of surviving pig. These findings help to quantify the impact of PEDv infection in the US and, ultimately, contribute to efforts to quantify the cost-effectiveness of disease prevention and control measures.

Mycobacterium bovis infection in a horse with granulomatous enterocolitis.

A 2-year-old dappled Percheron horse had a wasting condition that did not respond to antibiotic treatments and ultimately resulted in death. Thickening of the wall of the large colon and enlargement of the mesenteric lymph nodes were observed at postmortem examination, along with the presence of pinpoint whitish foci in the liver. Microscopic examination of affected tissues revealed diffuse chronic granulomatous enterocolitis, granulomatous mesenteric lymphadenitis, and multifocal granulomatous hepatitis. The DNA extracted from paraffin-embedded intestinal and lymph node samples was analyzed using both a polymerase chain reaction (PCR) assay and PCR-restriction endonuclease analysis and demonstrated the presence of Mycobacterium bovis.