Porcine circovirus 4 (PCV4) is a single-stranded DNA virus that is non-enveloped with an unsegmented circular genome roughly 1.7-1.8 kb in length. PCV4 belongs to the family Circoviridae and represents the fourth member of the genus Circovirus of which there are four known variants. PCV4 was first identified in China in 2019. Pigs were exhibiting serious symptoms, including porcine dermatitis and nephropathy syndrome (PDNS)-like signs