Senecavirus A (SVA), formerly known as Seneca Valley virus, is a nonenveloped, single-stranded, positive-sense RNA virus that belongs to the family Picornaviridae, order Picornavirales, and the prototype species of the genus Senecavirus. The genome is approximately 7.2 kb and is translated into a polyprotein in a host cell. The polyprotein is then cleaved into mature proteins, including 4 structural viral capsid proteins (VP 1–4) and 8 nonstructural proteins (L, 2A, 2B, 2C, 3A, 3B, 3C, and 3D). In 2014 and 2015, vesicular disease was reported in swine herds in the U.S. and Brazil. SVA was identified in serum, vesicular fluids, and swabs taken from ruptured vesicles. Recent experimental work has demonstrated a causative relationship between SVA infection and vesicular disease.