Changes

===Functional anatomy===

===Functional anatomy===

**Mucosa

*Mucosa

**Mucosal epithelium

**Mucosal epithelium

**Nares and epiglottis- stratified squamous

***Nares and epiglottis- stratified squamous

**Nasal cavity, paranasal sinuses, larynx, trachea - pseudostratified, columnar, cilliated

***Nasal cavity, paranasal sinuses, larynx, trachea - pseudostratified, columnar, cilliated

**Submucosa

**Submucosa

**Submucosal glands

***Submucosal glands

**Lymphoid tissue

***Lymphoid tissue

**Blood vessels, lymphatics and nerves

**Blood vessels, lymphatics and nerves

**Very rich blood supply to nasal mucosa

***Very rich blood supply to nasal mucosa

**Nasal chambers and turbinates

**Nasal chambers and turbinates

**Scrolls of turbinate bone

***Scrolls of turbinate bone

**Arrangements vary with species

***Arrangements vary with species

**Nasal septum

**Nasal septum

**Full length of nasal chamber in horses

***Full length of nasal chamber in horses

**2 openings into pharynx

****2 openings into pharynx

**Partial length in other species

***Partial length in other species

**Single opening into pharynx

****Single opening into pharynx

**Sinuses

**Sinuses

**Size, arrangement and number vary with species

***Size, arrangement and number vary with species

**Poorly developed in carnivores

***Poorly developed in carnivores

**Poor communication of frontal sinus in cats with nasal cavity

****Poor communication of frontal sinus in cats with nasal cavity

**Predisposed to frontal sinus bacterial infections

*****Predisposed to frontal sinus bacterial infections

**Maxillary sinus opening very large - 'maxillary recess'

****Maxillary sinus opening very large - 'maxillary recess'

**Maxillary sinus infections very uncommon in carnivores

*****Maxillary sinus infections very uncommon in carnivores

**Highly developed in horses

***Highly developed in horses

**Slit-like, high openings in horses

****Slit-like, high openings in horses

**Predisposed to bacterial infections

****Predisposed to bacterial infections

**Cheek teeth embedded within the maxillary sinuses

****Cheek teeth embedded within the maxillary sinuses

**Maxillary sinusitis secondary to tooth root abscesses

****Maxillary sinusitis secondary to tooth root abscesses

**Guttural pouch

**Guttural pouch

**Horses

***Horses

**Diverticulum of the eustachian tube with a thin slit-like opening at the rostroventral aspect into the pharynx.

****Diverticulum of the eustachian tube with a thin slit-like opening at the rostroventral aspect into the pharynx.

**Mucous secretions drain out of the pouch when the horse lowers its head

****Mucous secretions drain out of the pouch when the horse lowers its head

**Lined by respiratory epithelium

****Lined by respiratory epithelium

**Bordered by glossopharyngeal, vagus, accessory and hypoglossal nerves; sympathetic trunk; internal and external carotid arteries

****Bordered by glossopharyngeal, vagus, accessory and hypoglossal nerves; sympathetic trunk; internal and external carotid arteries

**Pathology

***Pathology

**Mycotic infections eg: Aspergillus fumigatus

****Mycotic infections eg: Aspergillus fumigatus

**Bacterial infections eg: Streptococcus equi var. equi ('Strangles') or S.equi var zooepidemicus

****Bacterial infections eg: Streptococcus equi var. equi ('Strangles') or S.equi var zooepidemicus

**Tympany - associated with dysfunction of the pharyngotubal opening resulting from thickening (oedema, inflammation) or obstruction by a mucosal fold (eg: foals)

****Tympany - associated with dysfunction of the pharyngotubal opening resulting from thickening (oedema, inflammation) or obstruction by a mucosal fold (eg: foals)

•*Defense mechanisms

 

==Defense mechanisms==

**Particle deposition  

**Particle deposition  

**Coiled nature of turbinates promotes turbulent airflow and impaction of large particles >10 μm in diameter onto the nasal mucosa

**Coiled nature of turbinates promotes turbulent airflow and impaction of large particles >10 μm in diameter onto the nasal mucosa