Respiratory Pathology I and II

Question 1

Name the main protective mechanisms of the lungs

Answer 1

• mucociliary apparatus –> for physical filtration
• secretion of defensins, antioxidants, collectins, IgA, lactoferrin –> for the innate and acquired immune systems
• alveolar macrophages and other immune cells
• high P450 enzyme activity, sensitive to toxic metabolites

Question 2

Define choanal atresia

Answer 2

no communication between the nasal cavity and the nasopharynx

Question 3

Nasal bot fact file

Answer 3

Oestris ovis flies
sheep are primary hosts
affected animals lose weight and BCS
may invade through cribiform plate and cause encephalitis

Question 4

Define rhinitis and list common causes. Name the types of rhinitis

Answer 4

inflammation and irritation of the MM of the nose
causes depend on breed, commonly viral, fungal, bacterial, tumours, foreign bodies, etc…

Types of Rhinits :
- pseudomembranous (no ulceration)
- fibronecrotic (firm adheration of fibrin)
- acute (loss of cilia, hyperplasia, inflammatory cells present)
- chronic (epithelial attenuation or metaplasia, polyps, fibrosis. classified based on inflammatory infiltrate)
- allergic (sporadic and seasonal)
- toxic
- atrophic (seen in pigs, caused by strains of Bordetella and Pasteurella

Question 5

Define the guttural pouch in horses and explain why it can be a problem

Answer 5

Guttural pouch is a diverticulum of the auditory tube in horses. can develop empyema (liquid build uo) or tympany (air build up) and affect nearby cranial nerves

Question 6

List possible pathologies of the larynx

Answer 6

laryngeal oedema
laryngitis
laryngeal paralysis in horses
laryngeal paralysis in dogs
laryngeal chondritis (ulceration at rostral margin of arytenoid cartilage)

Question 7

Name common pathological findings of the trachea

Answer 7

[ froth is a common PM finding in the trachea, especially in herbivores ]
brachycephalic airway syndrome
tracheal collapse
tracheal oedema and haemorrhage syndrome

Question 8

Define pneumothorax and list the different types

Answer 8

Air or gas in the pleura that causes atelectasis due to a loss of negative pressure.

spontaneous, may be 1st or 2nd. due to rupture of pulmonary bullae or underlying lung disease
traumatic, accidental puncture of the thoracic wall and visceral pleura

Question 9

Define hydrothorax

Answer 9

clear, watery transudate (colourless to light yellow) in the pleural and thoracic cavity.
low in protein and cell count
caused by increased venous pressure, lymphatic obstruction and hypoproteinaemia
chronically, makes pleura opaque with fibrosis and hyperplasia

Question 10

Define chylothorax

Answer 10

accumulation of milky, high triglyceride lymph fluid in pleura and thoracic cavity, often idiopathic

Question 11

Define haemothorax

Answer 11

blood in the pleura, usually traumatic

Question 12

Define pleuritis and explain the different types

Answer 12

inflammation of the pleura. often caused by infectious agents that arrive in the pleura via blood or from lung penetrating lesions.

fibrinous -> loose strands or large plaques of fibrin with lakes of fluid
pyothorax -> creamy, suppurative exudate
chronic -> lots of adhesions but seldom affects lung function

Question 13

Define pulmonary hypoplasia

Answer 13

reduced lung weight, often also resulting in reduced numbers of alveoli. normally caused by conditions that compress the lungs

Question 14

Define atelectasis

Answer 14

incomplete expansion of the lungs, making it look darker and sunken with a fleshy-firm texture. will not float in water.

may be obstructive (airway obstruction) or compressive (space-occupying lesions)

Question 15

Define emphysema

Answer 15

air filled spaces in the connective tissue and parenchyma, called blebs and bullae respectively. grossly, lung is pale and puffy

alveolar -> abnormal, permanent enlargement of alveoli due to septa destruction. no fibrosis.

interstitial -> subpleural and within interlobular septa. means there is air in the connective tissue and lymphatics

Question 16

Define and describe a lung oedema

Answer 16

air spaces in the lung are filled with liquid. lungs are wet, heavy, collapsed and ooze fluid when cut open.

causes include hydrostatic pressure, increased permeability, etc…

Question 17

Define a pulmonary thromboembolism (PTE)

Answer 17

An embolism that has ended up in the pulmonary tract.

in situ thrombi = microscopic, dissolve by themselves

embolic thrombi = grossly visible, end up in the lungs from veins

Question 18

Define lung infarction

Answer 18

The infarction of a segment of the lung due to blockage of the blood supply. rare, due to dual blood supply acting as a natural back-up.

Question 19

Name the different types of haemorrhages found in the lugns

Answer 19

pulmonary haemorrhage : multifocal to patchy, severe can cause haemoptysis or sudden death, common causes are abscesses eroding into vessels

equine exercise induced pulmonary haemorrhage (EIPH) : common in racehorses, pathogenesis incompletely understood

Question 20

Define pulmonary hypertension

Answer 20

when pulmonary arterial pressure is >30 mmHg, often due to vascular remodelling or an imbalance between dilation and constriction factors

lesions occur with secondary hypertension

Question 21

Define and explain airway disease

Answer 21

airway disease is the specific targeting of airways, due to a combination of necrosis and inflammation.

CS : coughing, impaired defences, failure to ventilate alveoli

Question 22

Define bronchitis and explain the pathogenesis

Answer 22

Bronchitis is the inflammation of the bronchi, caused by viral, bacterial, irritants, allergens, etc…

Pathogenesis : exudate -> sloughing of ciliated cells -> epithelial attenuation -> necrosis -> (fibrosis)

if stimulus is removed, there is healing

Question 23

Define bronchiectasis and describe the pathogenesis

Answer 23

Bronchiectasis is the permanent dilation of bronchi due to chronic obstruction and infection. Bronchi are unable to clear exudates from airways and cannot function.

Pathogenesis : destruction of walls -> luminal obstruction -> proteases from inflammatory cells weaken airway walls -> wall is pulled wider and wider -> may eventually inspissate

Question 24

Define bronchopneumoniaa

Answer 24

An exudative lesion of the broncho-alevolar junction, indicating an airborne entry of pathogens and/or foreign material

grossly : consolidation, lungs are dark red-purple, may ooze fluid, firm texture

lobular = affected and unaffected lobular, slow expansion
lobar = entire lobe consolidated, often with pleuritis

resolves is the agent is destroyed by the immune system

sequestrum includes a mass of necrotic lung, purulent exudate, fibrous capsule presence, foul smell, firm texture and grey-red in colour

Question 25

Interstitial and bronchointerstitial disease definition and causes

Answer 25

Damage and inflammation of the septa with a wide range of lesions

non-infectious causes : anaphylaxis, hypersensitivity, interstitial lung disease, neonatal distress, lipid pneumonia, alveolar filling disorders

Question 26

Name the different patterns of types of interstitial disease

Answer 26

eosinophilic interstitial pneumonia - see lymphoma and carcinoma commonly, seldom fatal, responds to steroids
eosinophilic pulmonary granulomatosis - CS include cough and nodular lesions with eosinophils/macrophages/fibrosis
acute interstitial lung disease of cattle - high fatality, CS includes open mouth breathing and dyspnoea. see lobular lesions in lung, red, rubbery, fail to collapse. cause unknown
donkey pulmonary fibrosis - common, incidental most likely, cause unknown
idiopathic pulmonary fibrosis of cats - uncommon, cause unknown, see patchy lesions of septa thickened by smooth muscle and fibrosis