Figure 1.

Schematic diagram depicting the flow of pigs through the breeding and gestation farm. Replacement gilts were born on the upstream gilt multiplier breeding farm, and were transferred to three different contract grower facilities. When gilts reached the appropriate age, they were then moved to the downstream isolation unit where they were vaccinated against influenza (FluSure XP^® Zoetis) and kept a minimum of 4 weeks. Gilts are then transferred to a breeding and early gestation unit where pigs are inseminated, and this is where the H4N6 index cases were detected. Once pregnancy is confirmed, pigs are transferred to one of two long-term gestation units. Piglets are sold and sows return to the breeding and gestation unit. Dates of clinical sample collection are noted and virologic and serologic results are described. Gilt, female pig that has not produced a litter. Sow, female pig that has already produced a litter.