A pulmonary abnormality of newborn lambs.

Nineteen pregnant ewes deliberately infected orally with Campylobacter coli/jejuni at either 80 or 120 days gestation and accidentally subjected to a period of heat stress during the latter half of pregnancy produced clinically normal but growth-retarded lambs at term. A group of 7 pregnant ewes uninfected with Campylobacter but subjected to the same heat stress produced lambs clinically and morphologically similar to the lambs of the other 2 groups. Microscopically, the lungs from 11 lambs showed areas of increased cellular density which were interpreted as pulmonary collapse. The cause remains unknown, but the lesion could have its origins in some form of airway obstruction associated with intra-uterine infection and/or heat stress.