The carriage of Pasteurella haemolytica in sheep and its transfer between ewes and lambs in relation to mastitis.

The possible presence of Pasteurella haemolytica in the mouth of lambs and on the skin of the teats of ewes was investigated. The organism was found in the mouth of ewes and lambs and, soon after lambing, on the teat skin of ewes. It was not isolated from the teat skin of pregnant ewes 1-14 days before lambing or from the teat skin one week after the lambs had been weaned. The transfer of P. haemolytica to the teat skin is undoubtedly mediated by the lamb. There is ample opportunity for the teat orifice to be exposed to P. haemolytica during the suckling period and it is known that only a few colony-forming units of virulent organisms are required to initiate mastitis.