Changes

***Results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from [[Mast Cells|mast cell]] degranulation and histamine release

***Results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from [[Mast Cells|mast cell]] degranulation and histamine release

*Histologically

*Histologically

**[[Bronchi and Bronchioles Inflammatory - Pathology#Acute bronchitis/bronchiolitis|Acute bronchiolitis]], characteristic of the bronchiolar response is the formation of syncytial giant cells  (formed by proliferating bronchiolar epithelial cells which may contain [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intracytoplasmic inclusion bodies]]), alveolar epithelium sometimes affected

**[[Bronchi and Bronchioles Inflammatory - Pathology#Acute bronchitis/bronchiolitis|Acute bronchiolitis]], characteristic of the bronchiolar response is the formation of syncytial giant cells  (formed by proliferating bronchiolar epithelial cells which may contain [[Cellular Inclusions|intracytoplasmic inclusion bodies]]), alveolar epithelium sometimes affected

**Obstruction of bronchioles by exudate - these may later become obliterated by the fibrous tissue of organisation

**Obstruction of bronchioles by exudate - these may later become obliterated by the fibrous tissue of organisation

*May contribute to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]

*May contribute to [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]