*Caused by [[Mannheimia haemolytica|''Manheimia haemolytica'' biotype A serotype 1 (90%)]] and ''[[Pasteurella multocida]]''
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*In young, growing cattle
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*In clinically normal cattle ''Mann. haemolytica'' serotype 2 is present in low numbers, only in nasal cavity and tonsils
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*Clinical signs: depression, anorexia, rapid shallow respiration, crusty nose with mucopurulent discharge, serous ocular discharge
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*Acute [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchopneumonia]] and may progress to [[Lungs Inflammatory - Pathology#Lobar pneumonia|lobar pneumonia]] with toxaemia
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*Pathology
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**Lobar, cranioventral exudative pneumonia with fibrin, [[Pleural Cavity & Membranes Inflammatory - Pathology|fibrinous pleuritis]], areas of coagulative necrosis
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*Histology
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**Large numbers of bacteria are usually associated with necrotic lesions