**Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
**Replicates in nasal epithelium -> throughout upper respiratory tract -> bronchial tree
**Syncytia form -> shed into bronchioles
**Syncytia form -> shed into bronchioles
−
**Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs - circulatory#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
+
**Complications include [[Lungs Ventilation - Pathology#Emphysema|emphysema]] and [[Lungs Circulatory - Pathology#Pulmonary oedema|oedema]], drop in milk yield in adult cattle
*'''Epidemiology''':
*'''Epidemiology''':
**Subclinical reinfections are important in spreading disease
**Subclinical reinfections are important in spreading disease