Induction of pneumonia in gnotobiotic calves following inoculation of Mycoplasma dispar and ureaplasmas (T-mycoplasmas).

Cloned cultures of Mycoplasma dispar and of Ureaplasma sp were inoculated endobronchially into gnotobiotic calves. The resulting pneumonia was estimated to involve 2 to 10 per cent of the lung although no clinical signs were observed. The histopathological lesions consisted of infiltration with mononuclear cells, cuffing (peribronchiolar lympho-reticular hyperplasia), catarrhal bronchiolitis and atelectasis. The results indicate that both M dispar and Ureaplasma sp are capable of causing sub-clinical cuffing pneumonia in calves.