The Journal of Medical Microbiology, Vol 14, Issue 1 89-95, Copyright © 1981 by Society for General Microbiology
Ovine systemic pasteurellosis caused by Pasteurella haemolytica biotype T
D. A. Dyson, N. J. Gilmour and K. W. Angus
A detailed study was made of lambs aged 5--7 months naturally infected with
Pasteurella haemolytica biotype T. In addition to the well known features
of such infections, previously unreported necrotic lesions of the tonsil,
oesophagus, pharynx and adjacent areas were consistently seen. Large
numbers of P. haemolytica were present in the tonsil, oesophageal lesions,
lung, liver and spleen, but few or none in other tissues. The evidence
indicated that the disease was not a true septicaemia. It is postulated
that P. haemolytica biotype T already present in the tonsils multiplies and
invades the adjacent tissues of the upper alimentary tract; groups of
organisms from this site enter the blood stream as emboli, most of which
lodge in the capillary beds of the lung and liver; rapid multiplication of
organisms in these tissues leads to death from the effects of endotoxin.
