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Diseases of the nasal cavity and sinuses (view source)
Revision as of 16:12, 7 February 2011
, 16:12, 7 February 2011no edit summary
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==Clinical signs and locations of sinonasal pathology==
==Clinical signs and locations of sinonasal pathology==
===Nasal discharge===
===Nasal discharge===
*Bilateral discharge:
*Bilateral discharge:
***Fungal infection
***Fungal infection
*Unilateral discharge:
*Unilateral discharge:
**Lesion is cranial to nasal septum eg: nasal or sinus lesion; pharyngeal or guttaral pouch lesion in horses
**Lesion is cranial to nasal septum eg: nasal or sinus lesion; pharyngeal or guttaral pouch lesion in horses.
===Type of discharge===
===Type of discharge===
**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)
*Prevents dessication of the mucosal epithelium
*Prevents dessication of the mucosal epithelium
*Contains antimicrobial substances
*Contains antimicrobial substances
*Immunoglobulin - IgA
*Immunoglobulin - [[IgA]]
**IgA produced by mucosal plasma cells
**[[IgA]] produced by mucosal plasma cells
**IgA can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance
**[[IgA]] can attach to specific pathogen antigens (viruses, bacteria) trapping them in the mucus for clearance
*Lysosyme
*Lysosyme
**Direct action on bacterial cell walls
**Direct action on bacterial cell walls
===Commensal bacteria===
===Commensal bacteria===
*The normal bacterial flora of the nasal cavity, pharynx, larynx and proximal portion of the trachea compete with potentially pathogenic bacteria and help to prevent their colonisation (competitive exclusion).
*The airway environment distal to the mid-portion of the trachea is effectively sterile.
===Reflexes===
===Reflexes===
*Sneezing
==Pathology of the upper airways==
==Pathology of the upper airways==
===Developmental abnormalities===
*Palatoschisis
*Nasal deviation
*All brachycephalic dog and cat breeds!
**Esp. English Bulldogs - stenotic nares, wide/long soft palate, hypoplastic trachea
===CIrculatory diseases===
*Epistaxis
**Haemorrhage from the nose
**Causes
***Inflammation eg: ulcerative rhinitis
***Neoplasia eg: infiltrating tumour, haemangioma
***Trauma
***Clotting defects
**Horse:
***Haemorrhagic nasal polyp
****'Ethmoid haematoma', 'Progressive haematoma' - arise from the ethmoid region and can extend to fill the nasal cavity. They can be difficult to control as they can recur after surgery.
****Histology - multiple areas of acute to chronic haemorrhage within a fibrous tissue stroma.
***Exercise-induced pulmonary haemorrhage
===Inflammatory disease===
[[Image:URT_mucosal_insult_flow_chart_-_for_resp_lectures.jpg|thumb|center]]
*Inflammation in the URT can be classified on:
**Location
***Nasal cavity - rhinitis
***Paranasal sinuses - sinusitis
***Guttural pouch and eustachian tube - eustachitis
***Pharynx - pharyngitis
**Type
**Type
***Grossly many inflammatory processes (eg: response to viral or bacterial infection) in the URT will begin as a serous discharge, and then progress to a catarrhal exudate, and then to purulent/pseudomembranous/haemorrhagic as neutrophils are recruited
***Grossly many inflammatory processes (eg: response to viral or bacterial infection) in the URT will begin as a serous discharge, and then progress to a catarrhal exudate, and then to purulent/pseudomembranous/haemorrhagic as [[Neutrophils|neutrophils]] are recruited
***Serous - transparent fluid exudate (acute inflammation)
***Serous - transparent fluid exudate (acute inflammation)
***Catarrhal - mucous exudation (acute to subacute inflammation)
***Catarrhal - mucous exudation (acute to subacute inflammation)
***Irritant or allergens
***Irritant or allergens
***Neoplasia
***Neoplasia
====Viral infections====
*Bovine herpesvirus -1
**Causes Infectious bovine rhinotracheitis (IBR)
**Highly infectious URT disease of cattle
**High morbidity, low mortality
**Aerosol transmission - requires close contact between animals
**BHV-1 infects the respiratory mucosal epithelial cells (intranuclear inclusion eosinophilic inclusion bodies)from nasal mucosa down to bronchioles
***leading to neutrophilic inflammation of varying severity.... serous -> catarrhal -> purulent nasal discharge, sneezing, coughing.
***with secondary bacterial infection (eg: Pasturella spp., Mycoplasma spp., Fusobacterium necrophorum) can lead to fibrinous to necrotizing inflammation; mucosal sloughing, ulceration... pyrexia, dyspnoea ... inhalation pneumonia... death.
**Clinical signs include coughing, discharge, lacrimation, and increased respiratory rate.
**Clinical disease most severe in young calves - can develop mucosal ulcerative lesions in the oesophagus and forestomachs and viraemia with multiorgan infection.
**Cause of abortion >5 months of gestation
*Cytomegaloviruses
**Porcine cytomegalovirus
***Causes Inclusion body rhinitis
****Disease of suckling piglets 1-5 wks of age
****Clinical signs: those associated with acute/subacute rhinitis (ie: serous nasal discharge, progressing to catarrhal or purulent discharge with time and secondary bacterial infections; sneezing; pyrexia)
****Morbitity high, mortality low
****Histology: large basophilic intranuclear inclusion bodies in the nasal and sinus respiratory epithelium with lymphocytic infiltration of the mucosa.
****Can develop viraemic stage, with inclusions in other organs eg: renal tubular epithelium. Piglets can die during this phase.
*Equine herpesvirus - 1, 4
*Feline herpesvirus -1
**One of the causes of Feline viral rhinotracheitis
***Viruses and bacteria are involved in the complex. The most frequent aetiologic agent is FHV-1, and less frequently feline calicivirus and/or ''Chlamydophia psittaci'' (NB: previously called Chlamydia psittaci var felis)
***All three agents infect URT respiratory epithelium, although FHV-1 has the highest affinity for this epithelium
***Feline calicivirus more frequently infects the oral mucosa -> ulcerative stomatitis
***C.psittaci more frequently infects the conjunctival epithelium -> chronic conjunctivitis
***Infection of the respiratory epithelium by FHV-1 results in a typical neutrophilic rhinitis with intraepitheial intranuclear eosinophilic inclusion bodies, with expected clinical signs
***Resolution of clinical signs usually occurs by 7-14 days.
***FHV-1 remains latent in the trigeminal ganglion, and can reactivate at times of stress. Can infect the cornea -> ulcerative keratitis.
****Pasturella multocida
***Occasional mortality in kitten or immunocompromised animals usually associated with secondary bacterial infection.
====Bacterial infections====
*''Pasturella multocida''
**Atrophic rhinitis in pigs
**Pigs aged 4-12 weeks old show clinical signs
**Catarrhal nasal discharge (due to an acute rhinitis), sneezing, coughing, can progress to dyspnoea and anorexia.
**Shortening and distortion of snout, secondary to nasal turbinate bone loss (histological evidence of osteolysis)
**2 forms of the disease
***'Progressive' atrophic rhinitis
****Due to infection of the nasal turbinates by P.multocida strains carrying the toxA gene that encodes for an osteolytic toxin. ''P.multocida'' adheres poorly to mucous membranes, and therefore requires a predisposing nasal insult to assist colonisation eg: co-infection with ''B.bronchiseptica''; or Porcine cytomegalovirus (inclusion body rhinitis)
****Turbinate bone atrophy is permanent and progressive
***'Non-progressive' atrophic rhinitis
****Due to infection of the nasal turbinates by ''Bordatella bronchiseptica'' strains alone, that carry a gene that encodes for a dermonecrotic toxin.
****Turbinate bone can regenerate by the time of slaughter
****Streptococcus equi
**'Snuffles' in rabbits
*****Streptococcus equi subsp. equi
****Most often ''P.multocida'' and/or ''B.bronchiseptica'' infection of the nasal mucosa
****Clinical signs (nasal discharge, sneezing) result from an acute to chronic rhinitis.
[[:Category:RVC]], [[:Category:R(D)SVS]], [[:Category:CUVS]], [[:Category:PG]],
*''Streptococcus equi''
**''Streptococcus equi subsp. equi''
[[Image:Purulent_nasal_discharge_horse.jpg]]
***Cause of 'Strangles' in horses
****Streptococcus equi subsp. zooepidemicus
***Infection with ''Streptococcus equi'' occurs after contact with contaminated feed, water bowls or an infected carrier horse
***Organism remains viable in environment for months
**URT infection can be indistinguishable clinically from Strangles, but does not cause suppurative lymphadenitis (cf: S.equi subsp. equi)
***Possibility of other sources of infection - in pharynx of in-contact dogs?
***Colonisation of nasopharynx causing:
***Chronic purulent rhinitis, sinusitis, eustachitis
**Aspergillus fumigatus
***Can progress to development of nodular masses in the guttural pouch consisting of inspissated pus and viable bacteria (guttural pouch empyema) - 'carrier' state
**Guttural pouch infections in horses - fungal plaques form on the adventitia of the carotid arteries can lead to catastrophic haemorrhage following erosion of carotid arteries!
***Regional suppurative lymphadenitis - can rupture onto skin of neck
**Nasal infection in dogs and cats - plaques develop on the nasal or paranasal sinus epithelium. Result in severe neutrophilic rhinitis/sinusitis. Can occur secondary to areas of mucosal compromise eg: adjacent to a space-occupying lesion.
***Bacteraemia with abscess formation in other organs (eg: liver, kidneys) - Bastard Strangles!
**Mucor spp.
**''Streptococcus equi subsp. zooepidemicus''
***Can infect the respiratory tract (nasal cavity, paranasal sinuses, trachea and bronchi/bronchioles)
**Cryptococcus neoformans
***URT infection can be indistinguishable clinically from Strangles, but does not cause suppurative lymphadenitis (cf: ''S.equi subsp. equi'')
**Most commonly in cats and dogs
**Chronic granulomatous rhinitis
====Fungal infections====
**Can invade through adjacent structures, eg: through the cribiform plate into the brain! These cases therefore can present as a primary neurological disease.
*Filamentous fungal organisms
**'' [[Aspergillus spp.|Aspergillus]] fumigatus''
**Insecta
***Guttural pouch infections in horses - fungal plaques form on the adventitia of the carotid arteries can lead to catastrophic haemorrhage following erosion of carotid arteries!
***Nasal infection in dogs and cats - plaques develop on the nasal or paranasal sinus epithelium. Result in severe neutrophilic rhinitis/sinusitis. Can occur secondary to areas of mucosal compromise eg: adjacent to a space-occupying lesion.
**''Mucor'' spp.
*Yeast-like fungal organisms
**''Cryptococcus neoformans''
***Most commonly in cats and dogs
***Chronic granulomatous rhinitis
***Can invade through adjacent structures, eg: through the cribiform plate into the brain! These cases therefore can present as a primary neurological disease.
====Parasitic infections ====
*''Oestrus ovis'' larvae in the nasal cavity of sheep and goats = Nasal bots
==Test yourself with the Respiratory System Pathology Flashcards==
[[Respiratory_System_Flashcards_-_Pathology|Respiratory System Pathology Flashcards]]
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