Risk factors associated with swine dysentery in East-European pig production units

The objective of the present study was to determine the risk factors for swine dysentery in East-European middle-size to large farrow to finish units with separate breeding and grower-finisher facilities. Ten breeding animals (3-10% of the female inventory) and 10 grower tinisher pigs (80-140 days-of age) were sampled in each herd for polymerase chain reaction testing (PCR) for Brachyspira hyodysenteriae (B hyo) in their feces. Of 139 farrow to finish units, 51 (36.7%) were positive, 49 (35,3%) were negative, and 39 (28.1%) were inconclusive for B hyo by PCR. In breeding subunits, twelve variables passed the screening criterion for risk factors (P<.2) for B hyo PCR positivity. The odds of the breeding subunits being B hyo PCR positive were 3.5 times greater when the grower-finisher subunit was positive and the fiber content of the diet was >6%. Use of "all in all out" farrowing policy and having >60% multiparous sows, each reduced the odds of being B hyo PCR positive about fourfold. In growing-finishing subunits, fourteen variables passed the screening criterion for risk factors (P<-2) for B hyo PCR positivity. B hyo PCR positive status of the breeding subunits and higher fiber content of the diet were the most influential variable, with the odds of the grower-finisher subunits being B hyo PCR positive almost eight times greater when the breeding subunit was also B hyo PCR positive. Grower-finisher B hyo PCR positivity was also associated with the percentage of pigs housed on concrete slats, with the odds of being positive 7.5 times higher for subunits where more that 70% of the animals were kept on concrete slats compared to all other floor types. There was a strong association between grower-finisher status and whether the animals were in outdoor lots with the odds of being B hyo PCR positive substantially lower for pigs in outdoor lots compared with all other surfaces