The Veterinary Record 162:147-152 (2008)
© 2008 British Veterinary Association
Relationships between clinical signs, pathological changes and tissue distribution of Mycobacterium avium subspecies paratuberculosis in 21 cows from herds affected by Johne's disease
C. Brady, MVB, MVM1,
D. O'Grady, MSc1,
F. O'Meara, BSc1,
J. Egan, MVB, MVM, PhD, FRCVS1 and
H. Bassett, MVM, PhD, MRCVS2
1 Central Veterinary Research Laboratory, Abbotstown, Castleknock, Dublin 15,
Ireland
2 Department of Veterinary Pathology, Faculty of Veterinary Medicine, University
College Dublin, Belfield, Dublin 4, Ireland
Twenty-one cows from eight herds affected by Johne's disease were
assigned to four groups: seven were not thriving and had persistent diarrhoea,
six were not thriving and had intermittent diarrhoea, four were not thriving
but did not have diarrhoea, and four were clinically normal. Postmortem,
macroscopic lesions consistent with Johne's disease were identified in 17 of
the cows and Mycobacterium avium subspecies paratuberculosis
(MAP) was isolated from all of them. However, except for the fact
that diarrhoea was correlated with the presence of lesions in the large
intestine there was little correlation between the presence or absence of
clinical signs and the lesions associated with Johne's disease. The tissue
distribution of MAP was also poorly correlated with either the
clinical signs or the lesions. The organism was widely distributed in 17 of
the 21 cows, including three of the clinically normal animals, and was present
in the mammary tissues of seven cows including two of the clinically normal
animals. Three distinct histopathological patterns were observed in the
affected intestines: infiltration of the lamina propria with giant cells,
tuberculoid lesions, and lepromatous lesions; the lepromatous lesions were
associated with extensive pathological changes.
Copyright © 2008 British Veterinary Association
