Changes

*Often undetected unless it causes facial deformity or a draining tract onto the skin

*Often undetected unless it causes facial deformity or a draining tract onto the skin

*Seromucous sinuitis in not significant, often an extension of viral infection in [[Nasal Cavity Inflammatory - Pathology#Rhinitis|nasal cavity]]

*Seromucous sinuitis in not significant, often an extension of viral infection in [[Rhinitis#Rhinitis|nasal cavity]]

*Purulent sinusitis tends to obstruct drainage -> chronic purulent sinusitis

*Purulent sinusitis tends to obstruct drainage -> chronic purulent sinusitis

*Most important in horses due to their complex sinuses

*Most important in horses due to their complex sinuses

**Rarely [[Respiratory Fungal Infections - Pathology#In Horses|fungal infections]]  

**Rarely [[Respiratory Fungal Infections - Pathology#In Horses|fungal infections]]  

*'''Secondary''':

*'''Secondary''':

**Most common sequel to [[Nasal Cavity Inflammatory - Pathology#Rhinitis|rhinitis]]

**Most common sequel to [[Rhinitis#Rhinitis|rhinitis]]

**Dental or periodontal disease (maxillary sinus)

**Dental or periodontal disease (maxillary sinus)

**Penetrating infections from dehorning wounds and fractures of facial bones (frontal sinus)

**Penetrating infections from dehorning wounds and fractures of facial bones (frontal sinus)