Changes

*A syndrome of catharral oculonasal discharge, [[Nasopharynx Inflammatory - Pathology#Infectious causes of pharyngitis|pharyngitis]] and [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchitis]] is relatively common in the initial stages

*A syndrome of catharral oculonasal discharge, [[Nasopharynx Inflammatory - Pathology#Infectious causes of pharyngitis|pharyngitis]] and [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchitis]] is relatively common in the initial stages

*Since one of the primary sites of action of this virus is lymphoid tissue, the resultant immunosuppression -> predisposition to secondary bacterial infection

*Since one of the primary sites of action of this virus is lymphoid tissue, the resultant immunosuppression -> predisposition to secondary bacterial infection

*May cause [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]] where [[General Pathology - Degenerations and Infiltrations#Cellular Inclusions|inclusions]] are found within alveolar macrophages

*May cause [[Lungs Inflammatory - Pathology#Interstitial pneumonia|interstitial pneumonia]] where [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|inclusions]] are found within alveolar macrophages

*Gross pathology:

*Gross pathology:

**Oedematous lungs, diffuse interstitial pneumonia

**Oedematous lungs, diffuse interstitial pneumonia

*Feline calicivirus more frequently infects the oral mucosa -> ulcerative stomatitis

*Feline calicivirus more frequently infects the oral mucosa -> ulcerative stomatitis

*''C.psittaci'' more frequently infects the conjunctival epithelium -> chronic conjunctivitis

*''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 [[General Pathology - Degenerations and Infiltrations#Cellular Inclusions|inclusion bodies]]  

*Infection of the respiratory epithelium by FHV-1 results in a typical neutrophilic rhinitis with intraepitheial intranuclear eosinophilic [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|inclusion bodies]]  

*Uncomplicated cases resolve in 2-3 weeks

*Uncomplicated cases resolve in 2-3 weeks

*FHV-1 remains latent in the trigeminal ganglion, and can reactivate at times of stress

*FHV-1 remains latent in the trigeminal ganglion, and can reactivate at times of stress

*Highly infectious URT disease of cattle  

*Highly infectious URT disease of cattle  

*Spread by movement of animals, aerosol transmission - requires close contact between animals

*Spread by movement of animals, aerosol transmission - requires close contact between animals

*Early stages (only first few days) may show [[General Pathology - Degenerations and Infiltrations#Cellular Inclusions|intracellular inclusions]] in the respiratory mucosal epithelial cells

*Early stages (only first few days) may show [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intracellular inclusions]] in the respiratory mucosal epithelial cells

*Leading to neutrophilic inflammation of varying severity.... serous -> catarrhal -> purulent  

*Leading to neutrophilic inflammation of varying severity.... serous -> catarrhal -> purulent  

*With secondary bacterial infection (eg: [[Pasteurella species and Mannheimia haemolytica|Pasturella spp.]], [[Mycoplasmas|Mycoplasma spp.]], [[Fusobacterium|Fusobacterium necrophorum]]) can lead to fibrinous to necrotizing inflammation; mucosal sloughing, ulceration... pyrexia, dyspnoea ... [[Lungs Inflammatory - Pathology#Aspiration pneumonia|inhalation pneumonia]]... death

*With secondary bacterial infection (eg: [[Pasteurella species and Mannheimia haemolytica|Pasturella spp.]], [[Mycoplasmas|Mycoplasma spp.]], [[Fusobacterium|Fusobacterium necrophorum]]) can lead to fibrinous to necrotizing inflammation; mucosal sloughing, ulceration... pyrexia, dyspnoea ... [[Lungs Inflammatory - Pathology#Aspiration pneumonia|inhalation pneumonia]]... death

*Often part of multi-aetiology disease complex (e.g. [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]), often followed by [[Pasteurella species and Mannheimia haemolytica|''Pasteurella sp.'']] obscuring viral origin

*Often part of multi-aetiology disease complex (e.g. [[Respiratory Bacterial Infections - Pathology#Enzootic pneumonia of calves|Enzootic pneumonia of calves]]), often followed by [[Pasteurella species and Mannheimia haemolytica|''Pasteurella sp.'']] obscuring viral origin

*Replicates in airway epithelial cells and results in an initial [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchitis -> bronchiolitis]] -> extension into [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|alveoli]], causing [[Lungs Inflammatory - Pathology#Bronchointerstitial pneumonia|bronchointerstitial pneumonia]]  

*Replicates in airway epithelial cells and results in an initial [[Bronchi and Bronchioles Inflammatory - Pathology#Infectious causes of bronchitis or bronchiolitis|bronchitis -> bronchiolitis]] -> extension into [[Lungs Inflammatory - Pathology#Infectious causes of pneumonia|alveoli]], causing [[Lungs Inflammatory - Pathology#Bronchointerstitial pneumonia|bronchointerstitial pneumonia]]  

*Early stages may show [[General Pathology - Degenerations and Infiltrations#Cellular Inclusions|intracytoplasmic inclusions]]

*Early stages may show [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intracytoplasmic inclusions]]

*The resulting exudate is predominantly neutrophilic

*The resulting exudate is predominantly neutrophilic

*Positive confirmation lies in a Fluorescent Antibody Test (FAT) to the specific virus on frozen sections of tissue

*Positive confirmation lies in a Fluorescent Antibody Test (FAT) to the specific virus on frozen sections of tissue

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

***Results from bronchoconstriction which results in airway obstruction - this constriction is thought to arise from [[Mast Cells - WikiBlood|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 [[General Pathology - Degenerations and Infiltrations#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 [[Degenerations and Infiltrations - Pathology#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]]

*Gross pathology - catarrhal discharge becoming purulent (secondary infection)

*Gross pathology - catarrhal discharge becoming purulent (secondary infection)

*Histology:  

*Histology:  

**Large basophilic [[General Pathology - Degenerations and Infiltrations#Cellular Inclusions|intranuclear inclusion bodies]] in the surface and subepithelium of nasal and sinus glandular epithelium with lymphocytic infiltration of the mucosa

**Large basophilic [[Degenerations and Infiltrations - Pathology#Cellular Inclusions|intranuclear inclusion bodies]] in the surface and subepithelium of nasal and sinus glandular epithelium with lymphocytic infiltration of the mucosa

**Bursting of nucleus with cell necrosis and sloughing of necrotic epithelium

**Bursting of nucleus with cell necrosis and sloughing of necrotic epithelium

*Can develop viraemic stage, with inclusions and focal necrotising lesions in other organs eg: renal tubular epithelium

*Can develop viraemic stage, with inclusions and focal necrotising lesions in other organs eg: renal tubular epithelium