There are 26 herds currently enrolled in the Swine Health Monitoring Project’s Time-to-Stability study. Twenty-two of those herds are far enough along to contribute testing results. There are 7 sites that have achieved stability as defined by 4 consecutive rounds of sampling each representing at least 30 litters. Before week 9 post-last-exposure, litters were not required to be sampled. Instead, environmental sampling at each of 6 locations including young piglet mats, weaned piglet mats, load out chutes, farrowing hallways, door knobs, and boot areas were usually requested from weeks 4-9 post-last-exposure in order to gauge environmental hygiene. Since some of the environmental sampling represents 1-2 litters (not enough to provide us with confidence of detection desired for low shedding prevalence), we have included that data in the tracking chart as yellow squares rather than the green squares which denote an adequate testing of at least 30 litters. [Source: SHMP Update 6/13/14]