Comparison of radiographic and necropsy findings of lung lesions in calves after challenge exposure with Pasteurella multocida.
OBJECTIVE
To test suitability of radiographic evaluation of lung lesions as a substitute for lung lesion scores derived by examination at necropsy in challenge-exposure models of bovine pneumonia.


METHODS
10 calves selected by body weight from 20 multiple-source male Holstein calves approximately 1 to 2 months old enrolled in a Pasteurella multocida challenge-exposure study.


METHODS
Calves were paired on the basis of weight and randomly assigned within pairs to vaccine or control (saline solution) group. By use of deep tracheal cannulation, calves were challenge exposed with a culture of virulent P multocida, observed for 10 days, euthanatized, and necropsied, and the lungs were scored for pneumonic lesions. Radiographic views of the lung fields of the calves were taken before challenge exposure and before necropsy and were evaluated for alveolar disease by a veterinary radiologist. Lung lesion scores were compared with radiographic evaluations.


RESULTS
There was a strong and significant correlation (R2 = 0.91, P < 0.001) between results of the evaluation of postchallenge-exposure radiographs and necropsy results. There also was also strong and significant correlation (R2 = 0.90, P < 0.001) between evaluation of the prechallenge-exposure radiographs and necropsy results.


CONCLUSIONS
Radiographic evaluation of lung lesions correlates well with lung lesions found at necropsy. The findings emphasize the need for caution in interpreting the results of challenge-exposure studies of bovine respiratory tract disease in which small numbers of calves are studied.
Jones
G F
GF
Biological Research & Development, Bayer Animal Health, Merriam, KS 66202-3632, USA.
Feeney
D A
DA
Mews
C
C
D000818:Animals; D001344:Autopsy / Q000662:veterinary; D001428:Bacterial Vaccines; D002417:Cattle; D008168:Lung / Q000000981:diagnostic imaging* / Q000382:microbiology / Q000473:pathology; D008297:Male; D016979:Pasteurella multocida / Q000276:immunology*; D012766:Pasteurellosis, Pneumonic / Q000000981:diagnostic imaging* / Q000382:microbiology / Q000517:prevention & control; D011859:Radiography
D001428:Bacterial Vaccines