Key Terminology & Definitions - Respiratory Flashcards
Pulmonary circulation
High flow, low pressure, supplies alveoli (cardiac output)
Bronchial circulation
Low flow, high pressure, supplies bronchi +/-pleura, smaller vessels without external elastic lamina (cardiac output)
Distinct lung lobules
Pig, cow, human
Intermediate lobulation
Horse, small ruminant
Absent lobules
Carnivores
Cat respiratory system
Have very thick tunic muscularis in pul aa.
Rodent respiratory system
Have cardiac muscle in their larger pul vv.
Pig and ruminant lungs
Right cranial lobe bronchus is first branch off trachea = common site of aspiration pneumonia
Marine mammals - differences
Have cartilage in bronchioles - resists pressures of deep diving, other species rely on tension from adjacent alveoli to keep bronchioles open
Classes of pul macrophages
Alveolar, dendritic, interstitial, pulmonary intravascular (PIMs), pleural
Alveolar macrophages
Resident, self-renewing pool - homeostasis and prevent inflammation, recycle surfactant, not very good at recognises inert substances (e.g. C, silicates)
Dendritic macrophages
Same as dendritic cells everywhere else
Interstitial macrophages
Least characterised type, function incompletely described
Pulmonary intravascular macrophages (PIMs)
Phagocytic and pro-inflammatory - involved in acute lung injury, only present in ruminants, horses, pigs, cats, whales + recruited in humans and dogs
Pleural macrophages
Not well characterised
Type I pneumocytes
Have a large SA and low antioxidant levels - prone to oxidative damage, death leads to sloughing and type II pneumocyte regenerative response
BALT
Bronchus-associated lymphoid tissue
Choanal atresia
No communication between nasal cavity and nasopharynx - camelids, forced to mouth breath, interferes w/ nursing and prone to aspiration pneumonia
Nasal amyloidosis
Submucosal in horses, may be associated w/ ulceration (not usually associated w/ systemic amyloidosis)
Epistaxis
Nosebleed - usually unilateral if in the nasal cavity but can come from anywhere in respiratory tract
Waldeyer’s ring
Ring of lymphoid tissues circling pro and nasopharynx
Rhinitis
Irritation and inflammation of the mucous membrane inside the nose - starts with serous exudate and progresses to catarrhal (localised or part of systemic disease)
Types and presentations of rhinitis
Pseudomembranous, Fibrinonecrotic/diphtheric, acute, Chronic: suppurative, eosinophilic, lymphoplasmacytic Idiopathic lymphoplasmacytic Allergic (atopic)
Pseudomembranous rhinitis
Free-layering covering of fibrin on surface with no underlying ulceration (can just remove fibrin)
Fibrinonecrotic/dipheric rhinitis
Fibrin firmly adhered to ulcerated surface - red + haemorrhaging
Acute rhinitis
Loss of cilia, epithelial attenuation, goblet cell hyperplasia, inflammatory cells
Chronic rhinitis
Epithelial attenuation or metaplasia (transformation of cells to squamous/cuboidal), fibrosis, polyps, lymphoid hyperplasia - classified based on inflammatory infiltrate
Suppurative rhinitis
Non-specific - bacteria e.g. salmonella enterica spp diarizonae in sheep, streptococcus canis and streptococcus zooepidermicus in dogs and cats, fungi e.g. Aspergillus sp. in dogs and cats (German shepherds), foreign body etc
Eosinophilic rhinitis
Often allergic + fungal tumours
Lymphoplasmacytic rhinitis
Non-specific + v. common
Idiopathic rhinitis
Important in dogs - inc mucus and turbinate destruction, mostly lymphoplasmacytic
Allergic (atopic) rhinitis
Seen sporadically in most species - type I hypersensitivity, pollen allergy discharge, lacrimation, nasal itching, sneezing, pale, thick, oedematous mucosa - can progress to nasal granuloma in cattle (chronic)
Granulomatous rhinitis
Protozoal agents - cryptococcus spp., rhinpsporidium seeberi, besnotia protozoal cysts
Cryptococcus spp.
Thick capsule, narrow-based budding
Rhinosporidium seeberi
Polyps with huge endosporulating sporangia (endospore with a capsule)
Besnotia protozoal cysts
Found in many other tissues
Sinusitis
Inflammation of sinuses - secretions build up, predispose to bacterial infection and chronic purulent inflammation, most important in horses - large complex sinuses with poor drainage close to teeth and prone to extension of periodontitis
Mucocele
Seromucous exudate
Empyema
Purulent exudate (accumulation of pus)
Progressive ethmoid haematoma
Horses - arise from ethmoid turbinates, mottled, fibrovascular mass of organising haemorrhages, siderosis, and mineral (thoroughbreds + Arabians, older animals)
Nasopharyngeal polyp
Inflammatory mass arising in middle ear or auditory (eustachian) tube, young cats
Cystic lesions
Paranasal sinus cysts in foals and young horses distort face + teeth, cystic nasal conchae in cattle -> progressive nasal obstruction
Guttural pouch
Diverticulum of the auditory (eustachian) tube in horses -
Laryngeal hemiplegia
Dorsal displacement of soft palate (close proximity to vagus n.)
Guttural pouch tympany
Air build-up in pouch - less common than inflammation, young horses
Larynx in horses
Abnormally short epiglottis predisposes to dorsal displacement of soft palate
Laryngeal oedema
Local or systemic inflammation, irritant inhalation, hyperthermia, anaphylaxis (physical damage)
Laryngitis
Occurs alone or with upper respiratory inflammation e.g. e.g. due to Fusobacterium necrophorum in calves (oral necrobacillosis)
Laryngeal paralysis in horses
Idiopathic degeneration of recurrent laryngeal nerve, almost always affects left side, denervation atrophy of cricoarytenoid muscles, cartilage sags into larynx
Laryngeal paralysis in dogs
Older males, large to giant breeds, predisposes to aspiration pneumonia, may be due to systemic muscular disease
Laryngeal chondritis
Ulceration at rostral margin of arytenoid cartilage - deforms laryngeal cartilage, causes inflammation and necrosis, short-necked sheep (Texels) + horses
Brachycephalic airway syndrome
Mostly dogs - stenotic nares, elongated soft palate, tracheal hypoplasia, tracheal rings overlap and the dorsal tracheal ligament in inapparent, inc airway pressure -> eversion of laryngeal saccules +/- tonsils, oedema, collapse of trachea and/or larynx
Tracheal collapse
Dorsoventral narrowing, coughing and exercising intolerance, wide, flaccid trachealis muscle, cartilage rings are abnormal shapes (tracheal hypoplasia) + bronchioles often collapsed (middle-aged miniature dogs + horses)
Tracheal oedema and haemorrhage syndrome
= ‘Honker syndrome’ - partial obstruction by haemorrhage and oedema of dorsal trachea (dusty environment)
Atelectasis
A complete or partial collapse of the entire lung or area (lobe) of the lung - caused by air or gas in pleura due to loss of negative pressure, fleshy or firmer texture (if foetal, will not float)
Pneumothorax
Air in thorax
Primary spontaneous pneumothorax
Rupture of pulmonary blebs or bullae, especially in dogs
Secondary spontaneous pneumothorax
Due to underlying lung disease e.g. ruptured parasitic cyst
Hydrothorax
Clear, watery transudate, colourless or light yellow, low protein and low cells, due to inc venous pressure, lymphatic obstruction (backflow of fluid in circulation), common in cats w/ cardiomyopathy
Chylothorax
Accumulation of milky, high triglyceride lymph fluid (usually idiopathic)
Haemothorax
Blood in pleura, usually traumatic but also rodenticide toxicity, ruptured tumours, lung lobe torsion, erosion of vessels by tumours of inflammation
Pleura
Continuous layer of mesothelium involved in fluid balance and inflammation
Fibrinous pleuritis
Loose strands or sometimes large plaques with lakes of fluid (from blood vessels)
Pyothorax - pleuritis
Creamy suppurative exudate
Chronic pleuritis
Lots of adhesions but seldom affect lung func - fibrin polymerised, elasticity of lungs compromised
Pleuritis - horses
Aspiration of pharyngeal contents, unilateral/bilateral, usually extends from lung lesion but reaction is so severe it’s hard to find + in septicaemic foals
Pleuritis - dogs
Hunting dogs, bilateral/unilateral, protozoal bacterial infection - Actinomyces spp., Nocardia, Bacteroides with characteristic sulphur granules, usually due to inhaled/migrating grass awns, or bite wounds, oesophageal perforation, bacteraemia
Pleuritis - cats
FIP common (multifocal pyogranulomas on pleura), pyothorax relatively common, variety of bacteria, most cases idiopathic
Pleuritis - pigs
Actinobacillus sp., Streptococcus suis, Haemophilus
parasuis, Mycoplasma hyorhinis
Pleuritis - cattle
Mannheimia haemolytica, Histophilus somni, traumatic reticuloperitonitis, Pasteurella multocida
Pulmonary hypoplasia
Reduced lung weight + often reduced no. alveoli e.g. hernias, thoracic masses, effusions, ribcage malformation, impaired foetal breathing movements (nervous/muscular deficits)
Bronchial atresia
Accumulation of mucus in lung (lack of patency)
Partial bronchial obstruction
Air trapping after birth (congenital lobar emphysema)
Lungs - lobe torsion
Right middle lobe in large, deep-chested dog breeds, cats
Left cranial lobe in small breed dogs
Obstructive atelectasis
Due to complete airway obstruction
Compressive atelectasis
Due to space-occupying lesions (hydrothorax, pleuritis, tumours etc), abdominal distention (bloat, ascites - mostly cranial lobes), pneumothorax, recumbent large animals develop on the ‘down’ side
Alveolar emphysema
Abnormal permanent enlargement of alveoli due to destruction of septa - imbalance between proteases and antiproteases
Interstital emphysema
Subpleural and within interlobular septa - air in the connective tissues and lymphatics, common in cattle
Blebs
Air-filled spaces in the connective tissue of the pleura, common cause of pneumothorax in dogs
Bullae
Air-filled spaces in the parenchyma that bulges into the pleura, common cause of pneumothorax in dogs
Overinflation of alveoli
(Not emphysema, but grossly resembles it) - due to airway obstruction or spasm (air trapping + failure to deflate), can be congenital in dogs
In situ thrombi
Usually microscopic + dissolve quickly after death (absence of microthrombi doesn’t rule out DIC)
Embolic thrombi
Usually grossly visible in diff organs
Lung infarction
Uncommon - due to dual blood supply
Septic emboli
Lots of bacteria, can cause acute oedema/interstitial disease
Fat emboli
Uncommon - can result from hepatic lipidosis, bone fractures or subcutaneous necrosis in diabetes or pancreatitis
Siderophage
Haemosiderin-containing macrophages
Equine exercise-induced pulmonary haemorrhage (EIPH)
Racehorses - lesions usually present in caudodorsal lung (pleural discolouration +/- fibrosis + siderophage accumulation)
Equine exercise-associated fatal pulmonary haemorrhage
Common cause of acute sudden death in racehorses, wide spread haemorrhage and oedema on histology, haemorrhage in all lung components - not necessarily severe EIPH as it is a diffuse process
Pulmonary hypertension
When pul arterial pressure >30 mmHg - due to vascular remodelling, imbalance between vasodilatory and vasoconstrictive factors
Pulmonary venous hypertension
Due to left heart failure + can eventually lead to arterial hypertension
Pulmonary veno-occlusive disease
Rare - rapidly progressive respiratory distress, firm lungs
Pulmonary vasculitis
Uncommon - septic vasculitis can arrive haematogenously or from adjacent pneumonia, specific causes e.g. heartworm, viral vasculitides
Uraemic pneumonopathy
Dogs - acute or chronic renal failure, similar lesions in hypercalcaemia, vit D toxcitiy
Eosinophilic bronchopneumopathy
Uncommon steroid-responsive disease of young dogs
Bronchiectasis
Permanent dilation of bronchi due to chronic obstruction and infection - bronchi are unable to clear exudates + can’t function, usually secondary to bacterial bronchopneumonia or bronchitis, sometimes immune-mediated or congenital
Primary ciliary dyskinesia (PCD)
Diverse array of problems involving cilia throughout the body and sperm, half of affected individuals have Kartagener’s syndrome
Kartagener’s syndrome
Sinusitis, bronchiectasis and situs inversus due to abnormal embryologic development
Pneumonia
Caused by bacterial or viral infection, in which the air sacs are inflammed
Bronchointerstitial pneumonia
Necrosis affecting bronchiolar and alveolar epithelium, bronchioles more commonly obstructed than bronchi - much smaller and less dilated
Bronchiolitis obliterans
Histological syndrome - sequel to chronic bronchiolar damage, fibrous polyps occlude lumen, severe impact on alveolar ventilation, may cause widespread hypoventilation and secondary hypertension, common in cattle with chronic pneumonia
Lobular bronchopneumonia
Affected and unaffected lobules, slow lesion expansion, most common in species with prominent septa (cattle)
Lobar bronchopneumonia
Consolidation of entire lobe, often accompanied by pleuritis
Chronic suppurative bronchopneumonia
If infection remains active, often secondary pathogens, primary cause not identifiable, may cause fibrosis, bronchiectasis, abscesses, sequestra
Sequestrum
Mass of necrotic lung, often separated by purulent exudate and fibrous capsule, firm, grey-red, friable, foul smell, permanent, non-functional nidus of infection
Aspiration pneumonia
Inhalation of any foreign material (usually fluid)
Bronchiointestinal disease
Epithelial necrosis in bronchioles and alveoli
Diffuse alveolar damage
Most common form of interstitial disease - damage to type I pneumocytes or endothelium
Anaphylaxis
Mostly in cattle, bronchoconstriction, alveolar and interlobular oedema
Hypersensitivity pneumonitis
Confinement-raised cattle, rarely horses, chronic inhalation of mould spores in hay, lesions centred on airways
Granulomatous interstitial penumona
TB, Rhodococcus, Nocardia, yeasts, parasites, some viruses
ARDS
Acute respiratory distress syndrome (interstitial lung disease in dogs), rapid progression, may see pneumothorax + gastro-oesophageal intussusception due to dyspnoea
Neonatal respiratory distress syndrome
Common in foals - herpesvirus septicaemia, meconium aspiration (in calves) -. failure of type II pneumocytes to secrete functional surfactant -> inc surface tension -> alveoli collapse, shear stress injures epithelium
Interstitial + bronchointerstitial pneumonia in foals
Often concurrent Rhodococcus lesions
Lipid pneumonia
Aspiration of oil droplets - foamy macrophages try to resorb oil and fill alveoli
Alveolar filling disorders
Buildup of abnormal material in alveoli - incidental, indicate airway obstruction, excess production and/or impaired removal of substances (foamy macrophages)
Alveolar proteinosis
Granular eosinophilic or amphophilic material made of surfactant proteins and phospholipids
Pulmonary hyalinosis
Macrophages and giant cells with hyaline material
Pulmonary alveolar microlithiasis
Laminated concretions in alveoli and sometimes septa, rare in animals + cause clinical signs if extensive
Multifocal osseous metaplasia
Well demarcated small nodules of bone
Pneumoconiosis
Lung disease due to inhalation of inorganic dusts (silicates), persist in macrophages, which trigger fibrosis
Anthracosis
Carbon - when animals exposed to pollutants, around airway bifurcations (branches) (migration of macrophages)
Direct interstitial disease, non-infections (toxic)
Toxic gas exposure NO2
Metabolites interstitial disease, non-infections (toxic)
Cause damage to cells with high P450 enzyme activity e.g. Perilla mint, mould beans, brassicas, pyrrolizidine alkaloids, crotalaria, paraquat (herbicide), fumonisin B1
Fog fever (3-methylindole toxicity)
L-tryptophan is metabolised to 3-MI in the rumen which is further metabolised to a substance that damages cell mems
Embolic pneumonia
Haematogenous arrival of agents - multifocal rounded foci of necrosis, inflammation, abscessation
Abscesses
Via emboli or from chronic bronchopneumonia -> cranioventral distribution +/- bronchiectasis or aspirated foreign material, can erode through pleura to cause empyema, into vessels + cause haemorrhage/into bronchi -> bronchopneumonia
Inflammatory airway disease (IAD)
Mild-moderate end of equine asthma syndrome, no clinical signs at rest, exercise intolerance and poor performance, excess mucus and coughing, doesn’t necessarily progress to RAO
Recurrent airway obstruction (RAO)
Severe equine asthma, AKA heaves, airway hyper-responsiveness + episodes of reversible airway obstruction due to bronchospasm in response to allergen exposure, often seasonal (dust exposure), genetic predisposition + previous viral injury, grossly unremarkable, changes most prominent in caudodorsal lung
Feline asthma syndrome
AKA feline allergic bronchitis - recurrent episodes of bronchoconstriction, cough, dyspnoea, excess mucus and smooth muscle hyperplasia in chronic cases, not fatal - self-limiting and responds to steroids
BAL
Bronchoalveolar Lavage Fluid Cytology
