Evidence that blood-borne infection is involved in the pathogenesis of bovine pneumonic pasteurellosis.
Five calves were inoculated intravenously with 10(8) colony forming units (cfu) of Pasteurella haemolytica A1; the mean score for pneumonic consolidation 3 days post-inoculation was 28%, and the mean clinical score was 7.8. Five calves inoculated intratracheally with 10(9) cfu of the same strain of P. haemolytica had comparable scores (34% and 8.8). Histological lesions of fibrinous pneumonia were similar in all calves. P. haemolytica was recovered from all but one of the affected lungs. From one calf killed in extremis 3 hours after intravenous inoculation, numbers of bacteria recovered from lung were 1,000-fold greater than from liver and spleen. A similar difference in bacterial numbers was also obtained from a gnotobiotic calf killed in extremis, 12 hours after intravenous inoculation of 10(8) cfu P. haemolytica. Evidence from these experiments supports the hypothesis that the blood-borne route is important in the pathogenesis of bovine pneumonic pasteurellosis.
Agricultural and Food Research Council, Compton Laboratory, Newbury, Berkshire, England.
L H
LH
Thomas
R N
RN
Gourlay
S G
SG
Wyld
K R
KR
Parsons
N
N
Chanter
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000097:blood / Q000209:etiology*; D005856:Germ-Free Life; D008168:Lung / Q000382:microbiology / Q000473:pathology; D010326:Pasteurella Infections / Q000097:blood / Q000209:etiology / Q000662:veterinary*; D011014:Pneumonia / Q000097:blood / Q000209:etiology / Q000662:veterinary*; D018805:Sepsis / Q000150:complications / Q000662:veterinary*