Give examples of viruses that cause rhinitis in pigs
inclusion body rhinitis (porcine cytomegalovirus), swine influenza
Give examples of viruses that cause rhinitis in horses
equine rhinovirus, equine influenza, equine rhinopneumonitis (equine herpesvirus type 1 and type 4), equine viral arteritis (equine arterivirus)
What is atrophic rhinitis?
atrophy of the nasal turbinates of pigs with distortion and shortening of the snout
Aetiology of atrophic rhinitis?
co-infection of the nasal mucosa with Bordatella bronchiseptica and a toxin-producing strain of Pasteurella multocida capsular type D (sometime A)
How does bordatella facilitate the pathology of atrophic rhinitis?
facilitates colonisation of nasal epithelium by the toxigenic Pasteurella. The toxin probably acts directly on bone cells of the nasal turbinates to cause the loss
What is strangles?
haemolytic streptococci of Lancefield group C, which is a common inhabitant of the equine nasopharynx.
Strangles typically is characterised by
suppurative rhinitis, pharyngitis and lymphadenitis of the lymph nodes of the head and neck that drain the upper respiratory tract
Complications of strangles?
metastatic abscesses (often to the mesenteric and mediastinal lymph nodes), retropharyngeal abscesses can rupture into the guttural pouch (gutteral pouch empyema or chondroid formation), purpura haemorrhagica
What is purpura haemorrhagica?
acute vasculitis. urticaria and extensive oedema of ventrum, head and distal limbs. Can be a complication of strangles
Aetiology of glanders?
Rhinitis of glanders is characterised by?
multiple small nodules in the nasal mucosa composed of cores of neutrophils surrounded by a rim of macrophages and granulation tissue. there is fever and head/neck lymphadenitis
What is the most common cause of mycotic rhinitis in the dog?
Infection of Aspergillus fumigatus in the dog causes
chronic necrotising inflammation with friable exudate containing necrotic tissue and fungal hyphae. Can be aggressive and cause destruction of turbinates and nasal septum.
Aetiology of granulomatous rhinitis in cats?
Cryptococcus neoformans in cats is characterised by?
formation of nodules or destructive masses which often result in facial swelling. in severe cases, extension from nasal cavity to involve skin and oral mucosa
Inflammatory disease involving the pharynx, larynx and trachea areas are important because of the potential (2)
to obstruct airflow or to cause aspiration pneumonia
Filaroides osleri forms?
bodules around the tracheal bifurcation - submucesal nodules (up to 1cm diameter)
Filaroides osleri is associated with?
a mild chronic inflammatory reaction when the parasites are alive - subsequently, when the parasites die, an intense foreign body reaction develops
Examples of viral disease which cause inflammation of the larynx and trachea?
IBR (infectious bovine rhinotracheitis) and feline viral rhinotracheitis
Tracheal collapse is more commonly seen in
dogs, especially the miniature dog breeds as well as horses and cattle
Gross appearance of tracheal colapse?
flattened dorsoventrally with a widened, flaccid dorsal tracheal membrane
Examples of non-inflammatory disease of the larynx/trachea?
horses (usually unilateral and causes roaring) and occasionally dogs (usually bilateral) develop paralysis of the larynx
neurogenic atrophy of the left cricoarytenoid muscle causes?
left arytenoid cartilage to sag into the laryngeal lumen during inspiration
laryngeal oedema can occur...
systemic anaphylaxis, associated with trauma (improper endotracheal tubing), irritant gases
laryngeal and tracheal tumours can be of what origin?
cartilage and muscle origin and can occur with squamous cell carcinomas
inflammation of the bronchi
chronic bronchial irritation/injury can result in
Excess production of mucus as a result of goblet cell hyperplasia. Replacement of ciliated epithelium by more resistant but relatively non-functional squamous epithelium (squamous metaplasia). Bronchiectasis
Examples of bronchial inflammatory disease?
kennel cough/infectious tracheobronchitis, chronic bronchitis in dogs, bronchiectasis in cattle
Kennel cough is characterised pathologically by
persistent tracheobronchial inflammation
In severe cases of kennel cough, what happens??
extension to serous/mucopurulent rhinitis or cranioventral brochopneumonia with tonsils and RPLN enlargement
Aetiology of kennel cough
Bordetella brochiseptica but also possibly PI2 (parainfluenza-2) and CAV2 (canine adenovirus 2)
Necropsy findings of chronic bronchitis in dogs?
excess mucoid or mucopurulent exudate within the trachea and lower airways. the underlying bronchial mucosa is thickened, hyperaemic and oedematous (consequence of hypertrophy and hyperplasia of the glands and extensive infiltration of the lamina propria by inflammatory cells.
How is chronic bronchitis in dogs connected to cor pulmonale?
smooth muscle hypertrophy in the pulmonary arteries occurs which results in pulmonary hypertension leading to cor pulmonale
What is bronchiectasis in cattle
permanent saccular or cylindrical dilatation of bronchi as a result of the accumulation of exudate within the lumen and partial rupture of bronchial walls
Classical appearance of bronchiectasis
characterised by sac like nodules in the lungs which are filled with purulent exudate.
Why are cattle particularly prone to the development of bronchiectasis?
combination of complete lobular septation and lack of collateral ventilation
Bronchiectasis usually occurs
secondary to chronic bronchitis in which there is a weakening of the bronchial wall
Bronchiolar epithelium is highly susceptible to injury for reasons thought to include (2)
presence of clara cells which contain oxidases that can locally generate metabolites that are toxic. vulnerability to free radical damage
In species with poor collateral ventilation in the lungs (like ruminants), when bronchioles obstruct...
lung tissue supplied by that bronchiole collapses (atelectasis) and becomes non-functional
Bronchiolitis can occur via
an extension of bronchitis or currently with bronchitis and pneumonia. can occur as a distict entity (certain viral infections; pulmonary toxcity)
What is bronchiolitis obliterans
lesion caused by exudate that can't be cleared so infiltration by fibroblasts leads to development of organised polyp-like masses within the bronchiolar lumen
What lung cell are the most susceptible to injury?
type I pneumocytes. irreversible injury results in swelling and sloughing of these cells. Repair possible if underlying basement membrane is intact. type II division occurs.
what is alveolar epithelialisation?
in severe, diffuse form of alveolar injury, the process of type II pneumocyte division after irreversible type I injury leads to the appearance of a gland
what are hyaline membranes?
microscopic eosinophilic bands formed by a combination of pulmonary surfactant and plasma proteins which can leak into the alveoli following type I pneumocytes and alterations in the blood-air barrier.
altered texture of lung (firmer) due to accumulation of exudates
inflammation that takes place in the alveoli and their walls
inflammation focused on bronchi, bronchioles and adjacent alveolar lumens. Originates and extends from terminal bronchioles.
Most common causes of bronchopneumonia
mycoplasma infections or aspiration of foreign material
Supprurative bronchopneumonia characterised by
neutrophils, cell debris and macrophages within the airway and alveolar lumens
Consequences of suppurative bronchopneumonia
Resolution (exudates removed via mucociliary escalator). Progression to chronic suppurative BP in which case any or all of the following may develop (bronchiectasis, pulmonary abscessation, pleuritis and adhesions, atelectasis or overinflation, BALT hyperplasia)
Fibrinous bronchopneumonias compared to suppurative bronchopneumonia
generally more severe and can cause sudden death due to associated toxaemia
Fibrinous bronchopneumonias are sometimes also called
lobar pneumonia due to involvement of entire lobes and pleural surface
Fibrinous bronchopneumonia consequences
due to severity, less likely to resolve completely -> fibrosis and adhesions
Interstitial pneumonia primarily occurs
in alveolar walls rather than in alveolar spaces
During interstitial pneumonia, injury to alveoli may cause
protein and fluid exudation -> hyaline membrane formation. Exudative phase is followed by proliferative phase where type II pneumocytes proliferate to replace the damaged type I cells
Characteristics of acute interstitial pneumonia
may be transient (in some viral infections). May be severe and associated with life threatening pulmonary oedema (ARDS)
Chronic interstitial pneumonia is dominated by
fibrosis of alveolar walls and proliferation of type 2 pneumoncytes
Bronchointerstitial pneumonia is common in
viral infections like RSV
What is embolic pneumonia
lung inflammation by haematogenous spread of infections into the lung
Distribution of lesions of embolic pneumonia
no orientation around airways and can be in any lung region, but most often affects the caudal lobes and inflammation is oriented around pulmonary arterioles or alveolar capillaries
Pulmonary abscesses can be a consequence of
septic emboli lodging in pulmonary vessels; extension from severe focal suppurative bronchopneumonia; aspiration of foreign material; direct penetration
Equine influenza causes
mild bronchointerstitial pneumonia, often complicated by secondary bacterial infection (e.g. strep)
equine viral rhinopneumonitis causes
mild bronchointerstitial pneumonia
rhodococcus equi occurs in
foals and immunosuppressed adelts
Rhodococcus equi causes
severe bronchopneumonia. R equi survives intracellularly causing suppurative bronchopneumonia and abscess formation (abscesses can coalesce to give large areas of confluent necrosis
shipping fever in cows manifests as
per-acute/acute septicaemia or in less acute forms more organ specific pathology can occur
Shipping fever in cows is caused by?
Pasteurella (P. multocida and P. haemolytica now called Mannheimia haemolytica), stress, and possibly viruses (RSV and PI3)
Enzootic pneumonia in cattle often caused by
viruses (e.g. PI3) or Mycoplasmas (M. dispar, M bovis). Secondary bacterial involvement then causes the elsions to progress (A pyogenes, P multocida)
Enzootic pneumonia in cattle clinically....
usually relatively mild and typified by lesions of bronchointerstitial pneumonia
Sequelae to tuberculosis
primary complex (initial focus of infection at portal of entry plus regional lymph node involvement with 90% exhibiting pulmonary form which can progress to caseous necrosis). Miliary TB if the infection is not contained in primary complex.
Respiratory Syncytial Virus usually occurs
associated with winter housing
Gross pathology of RSV
in severe cases is characterised by cranioventral atelectasis and consolidation. Additional frequent gross finding is interstitial emphysema which is more prominant in the caudal lung lobes
Emphysema in RVS results from
bronchoconstriction which results in airway obstruction, which is though to arise from mast cell degranulation and histamine release
characteristic of bronchiolar response in the formation of syncytial giant cells (formed by proliferating bronchiolar epithelial cells which may contain intracytoplasmic inclusion bodies)
two viruses causing respiratory pathology in dogs?
parainfluenza virus type 3 and canine distemper virus
What does PI3 cause in dogs?
induces acute respiratory disease in a range of species including ruminants, but is a multi-aetiology disease complex
What kind of virus is PI3?
replicates in airway epithelial cells and results in an initial bronchitis causing bronchiolitis which extends into alveoli (exudate is predominantly neutrophilic)
canine distemper virus is
a syndrome of catarrhal oculonasal discharge, pharyngitis, and bronchitis. Since primary site of action is lymphoid tissue, the resultant immunosuppression leads to predisposition of secondary bacterial infection
Maedi visna virus is also known as
lymphoid interstitial pneumonia
Gross findings of maedi visna virus
lungs fail to collapse properly on opening the chest and can weigh more than twice the normal weight. lungs are mottled grey/tan colour - the lesions can vary from irregular grey speckling to homogenous grey consolidation. Associated bronchial and mediastinal ln often enlarged
histology of maedi visna
extensive lymphoid proliferation around perivascular, peribronchial and peribronchiolar sheaths associated with pulmonary lymphatics. many contain germinal centres and smoth muscle hyperplasia (term bronchiole and alveolar walls)
pasteurellosis in sheep usually occurs
in lambs in late spring/early summer with pathology similar to that described for cattle
What is PRRS?
porcine reproductive and respiratory syndrome
PRRS is characterised clinically by
influenza-like illness oserved consisting of a tronsient loss of appetite, slight hyperthermia and respiratory distress
PRRS gross characteristics
lungs of affected piglets there may be an anterior lobe pneumonia however superimposed infections are common
porcine enzootic pneumonia aetiology
porcine enzootic pneumonia causes
lesions of bronchopneumonia which may be suppurative or catharral
Characteristic gross feactures of porcine enzootic pneumonia
confluent consolidation of the cranioventral lung lobes
Importance of porcine enzootic pneumonia
economically highly significant although most infections are moderate to mild unless complicating secondary infection
pasteurellosis in pigs causes
a severe acute fibrinous pneumonia in pigs as described in ruminants however most significant is secondary to underlying mycoplasma pneumonia resulting in suppurative bronchopneumonia with abscessation and pleuritis
aspergillosis is a disease significant in
birds. uncommon in animals
aspergillosis initiated following
inhalation of spores, most likely source is mouldy feed and bedding. immunodeficiency may centribute to colonisation
gross lesions of animals with aspergillosis?
multiple discrete grey-white nodules which develop around fungal colonies. blood vessels can become involved in the lesions leading to invasion, haemorrhage or thrombosis
Pathology of pneumocystis carinii
diffuse interstitial pneumonia in which the alveoli are filled with pale staining acidophilic material
Fog fever aka acute bovine pulmonary emphysema and oedema is usually seen
in adult beef cattle in the autumn and is associated with a change in pasture
pathogenesis of acute bovine pulmonary emphysema and oedema
ingestion of L-tryptophan in the pasture which is metabolised to 3-methylindole -> bloodstream -> lungs
Paraquat poisoning in dogs and cats - lesions?
range from acute (oedema, haemorrhage, hyaline membranes) to chronic (fibroplasia of alveolar septae, replacement of alveolar cells with type II cells)
Extrapulmonary lesions to note following paraquat intoxication?
necrosis of adrenal zona glomerulosa and renal tubular epithelium
larvae are in transit to the lungs and no pulmonary lesions apparent
what is the prepatent phase of dictyocaulus
larvae appear in alveoli causing aleolitis, bronchiolitis and bronchitis. Associated infiltration of neutrophils, eosinophils and macrophages which can plus the airways resulting in collapse distal to the lesion
what is the patent phase of dictyocaulus
lesions: parasitic bronchitis and parasitic pneumonia
due to the presence of large numbers of worms in the bronchi. histologically there is pronounced inflammatory (eosinophil) infiltrate and epithelias hyperplasia
caused by aspiration of eggs and larvae into the alveoli provoking a 'foreign body' type response. Grossly this is evident as dark red collapsed areas
Postpatent phase of dictyocaulus
recovery phase. Alveolar epithelialisation or superimposed bacterial infection occurs
What is alveolar epithelialisation and gross appearance after postpatent phase of dictyocaulus?
type II cells proliferate due to damage of type I cells. grossly evident as pink/rubbery lungs which don't collapse properly. often there is associated interstitial emphysema and oedema
gross pathology of d. arnfieldi
characterised by raised focal over-inflated areas in the caudal lung lobes
histology of d arnfieldi lesions
consist of central parasites and associated chronic catharral bronchitis. there is hyperplastic bronchial epithelium and surrounding lymphoid infiltration
Clinical significance of M capillaris
rarely any clinical significance even with large infestations
Intermediate host of muellerius capillaris
slugs and snails which infective larvae can survive many months in
lesions of m capillaris
firm 'lead-shot' nodules scattered throughout the parenchyma but most obviously in the dorsal regions of the caudal lung lobes
parasites of bronchi-bronchioles of pigs
histological lesions of metastrongylus
similar to dictyocaulus (catharral and eosinophilic bronchiolitis and bronchitis), however the lesions seldom become as extensive as can occur in dictyocaulus infections
cat lungworm seen wherever the intermediate host are found and adults like in respiratory bronchioles and alveolar ducts
gross lesions of aelurostrongylus
evident as multifocal subpleural firm yellow nodules scattered throughout the parechyma although they are more frequent at the periphery.
histology of aelurostrongylus
eggs and larvae in alveolar spaces cause FB reaction. submucosal gland hypertrophy and smooth muscle hypertrophy in airway and vessel walls also occurs
clinical signs of aelurostrongylus
mild although heavy infestations may cause chronic coughing. airway eosinophilia may be detected can be confused with asthma diagnosis
a vasorum in pulmonary arteries and right ventricle of dogs and foxes where they cause a proliferative chronic arteritis and interstitial eosinophilic pneumonia which can cause right sided heart failure
Hydatid cysts are
intermediate stage of echinococcus granulosus found in lungs. little clinical significance. zoonotic!
Name two type I hypersensitivity diseases of the lungs
feline asthma/allergic bronchitis, pulmonary infiltration with eosinophilia
feline asthma is usually dominated by
eosinophils and some affected cats also have circulating eosinophilia
feline asthma causes
recurrent cough/dyspnoea associated with bronchoconstriction
pulmonary infiltration with eosinophilia is dominated by
eosinophils in the airways
Name three type III hypersensitivity diseases in lungs
condition that arises due to repeated inhalation of spores of thermophilic actinmycetes in mouldy hay (occurs primarily in winter)
pathogenesis of bovine farmers lung?
sporse penetrate to the level of terminal bronchioles and alveoli throughout the lung which results from a type III hypersensitivity reaction to the inhaled fungal spores
Macroscopically.. bovine farmers lung...
lungs appear normal however on close inspection, numerous small grey nodules representing lymphoid reaction are evident
histologically... bovine farmers lung...
lymphocytic/plasmacytic bronchitis/bronchiolitis. associated thickening of the alveolar septae is also present. lesions can progress to severe interstitial fibrosis and type II hyperplasia. extreme cases, vascular compromise may lead to pulmonary hypertension and cor pulmonale
What is diffuse fibrosing alveolitis?
a catch all for end stage of a number of different diseases including EAA, reinfection syndrome and fog fever.
COPD is clinically characterised by
chronic coughing and poor performing
pathogenesis of COPD
involves sensitivity of the airways to environmental allergens - type III sensitivity
Gross appearance of COPD?
affected lungs are often surprisingly unremarkable except in extreme cases in which alveolar emphysema may be present
Histological appearance of COPD?
lesions are consistent with a chronic generalised bronchiolitis. plugging of airways with mucus, lymphoplasmacytic infiltration, goblet cell metaplasia and smooth muscle hypertrophy
Bronchiolitis in COPD is characterised by
a variable neutrophil response
Aspiration pneumonia leads to?
severe necrotising pneumonia and in very severe cases can progress to gangrenous pneumonia
Gangrenous pneumonia can occur following?
severe infections in which tissue becomes necrotic and is then invaded by putrefactive saprophytes (rare)
usual cause of gangrenous pneumonia?
administration of medicines or as a sequel to aspiration pneumonia. dead tissue undergoes liquefactive necrosis forming a cavity which is surrounded by intense hyperaemia and inflammation
endogenous lipid pneumonia?
cats > dogs, subclinical. accumulation of lipids (surfactant) in pulmanory macrophages leading to white nodules
exogenous lipid pneumonia associated with?
inhalation of oil, paraffin, etc.
exogenous lipid pneumonia results in
a reaction dominated by macrophages which fill the alveoli and interstitial thickening (mononuclear cells and fibrosis)
uraemic pneumonia causes
increased permeability of the blood-air barrier and therefore can cause pulmonary oedema. there may also be degeneration and calcification of smooth muscle and connective tissue fibres
incomplete expansion of the lung at birth (congenital) or collapse of previously air-filled lung (acquired)
causedy be complete airway obstruction usually by inflammatory exudate, foreign bodies, parasites or tumours. easier in animals with poor collateral ventilation like ruminants (cats and dogs harder)
caused by pleural intrathoracic or intrapulmonary space-occupying lesions. fluid, blood, exudate can cause compression atelectasis
compressive atelctasis in large animals commonly occurs
below a sharply-demarcated fluid line
complete lung collapse which occurs in pneumothorax
What are the different types of atelectasis
obstructive, compression, massive, recumbency (hypostatic), and defective surfactant production
What is emphysema
increased air in the lungs and is always secondary to some underlying entity or agonal change at slaughter and secondary to obstruction of airflow
sequelae of alveolar emphysema
distension and rupture of alveolar walls leads to formation of air 'bubbles' in the parenchyma
interstitial emphysema is most common in what species and why?
cattle due to pulmonary microanatomy and occurs especially with RSV infection
sequelae of interstitial emphysema?
air leads to interlobular connective tissue and can form bullae leading to bullous emphysema
Mechanisms in place to protect the lung from the entry of circulatory fluid into alveolar spaces
alveolar epithelium and its intercellular junctions are highly impermeable to fluid and seal off alveolar spaces. interstitium of alveolar septa is at lower pressure than intra-alveolar pressure. interstitial pressure becomes increasingly sub-atmospheric toward fascia surrounding vessels and airways toward pulmonary hilus
excessive fluid in the lung which generally begins as interstitial oedema characterised by expansion of perivascular and peribronchial and peribronchiolar fascia and distension of interstitial lymphatics
occurs only when interstitial compartment is overwhelmed and fluid floods the airspaces
Major causes of pulmonary oedema are
Increased capillary or type I epithelial permeability. Increased capillary hydrostatic pressure (cardiogenic oedema) or leftsided/biventricular heart failure. Decreased plasma oncotic pressure
Increased capillary or type I epithelial permeability is caused by
systemic toxins, shock, inhaled caustic gases
Pulmonary haemorrhage is a potential sequel of (4)
septicaemia, bleeding disorders, DIC and severe congestion
EIPH commonly occurs in? haemorrhage is?
horses during racing or training and the haemorrhage is dorsocaudal
Pulmonary infarction is
rare and doesn't follow embolism or thrombosis unless pulmonary circulation is already compromised like during general circulatory collapse or passive congestion of heart failure
Pulmonary hypertension is caused by
left-to-right vascular shunts or increased resistance of the pulmonary vascular system
Pulmonary hypertension is most commonly a sequel of
widespread fibrosis in the lung or chronic bronchitis or bronchiolitis which stimulates hypertrophy in the walls of small arteries