Spontaneous pustular dermatitis in a newborn piglet associated with a poxvirus.

Poxvirus was recovered from pustular skin lesions in a newborn piglet. The lesions were present at birth, suggesting transplacental infection had occurred. The lesions were circular, 1 cm in diameter, and were found over the entire skin surface, bulbs of the heels, coronets, tongue and buccal mucosa. Histologically, cells in the stratum intermedium were undergoing ballooning degeneration and necrosis, coalescing to form vesicles. The lumen of vesicles was filled with fluid and inflammatory cells. Degenerating epithelial cell nuclei were often vacuolated and eosinophilic intracytoplasmic inclusions were in many ballooned cells. The size and morphology of the virions recovered from vesicular fluid, place them in the poxvirus group.