Bronchial Diseases Flashcards
What is the role of the cough reflex?
Protective mechanism
- Assists mucociliary clearance
- Expels inhaled particulate material
- Protects against inhaling particles/irritants
Where are mechanoreceptors and chemoreceptors located?
Mechanoreceptors – larger airways
Chemoreceptors – medium airways
Where are cough receptors most numerous?
Larynx > Trachea > Bifurcation > Bronchi
None in bronchioles or alveoli
What are the 3 main causes of a cough?
Compression of mainstem lobar bronchi
Stimulation of cough receptors
Excessive mucus/fluid/inflammation
What are the DDx for compression of mainstem lobar bronchi -> cough?
- Left atrial enlargement
- Tracheobronchial / Bronchial Lymph node enlargement
- Neoplasia
What are the DDx for stimulation of cough receptors?
Laryngeal disorders
Tracheal disorders
Bronchial disorders
What are the DDx for excessive mucus / fluid / inflammation -> cough?
(usually soft / moist / ineffectual cough)
- Pneumonia
- Bronchopneumonia
- Pulmonary oedema
Describe the presentation of a cough when caused by cardiac disease
- Normal/increased HR
- Regular sinus rhythm, sinus tachycardia or arrythmias
- Occur mainly at night, when resting/sleeping
- Usually a heart murmur present
- Diastolic gallops possible
Describe the presentation of a cough when caused by respiratory disease
- Normal or decreased HR
- Sinus arrythmia
- Occur mainly when excited/exerted
- No murmur
- No diastolic gallops
What information would you need to gather from the history of a coughing patient?
- Environment
- Worming history
- Travel history
- Recent events / illnesses / changes
- How long coughing? Onset?
- Description of the cough. When worse?
- Is the cough really a cough?
- Any change in bark?
- Does the dog sleep normally?
What information would you need to gather from the clinical exam of a coughing patient?
- Observation (respiratory rate / pattern / any dyspnoea / any spontaneous coughing)
- Listen to all lung areas during normal quiet (non-panting) respiration. Identify adventitious respiratory sounds.
- Listen to and palpate URT
- Percussion
- Thoracic compressibility (cats)
- Attempt to induce a cough – auscultate following cough
Cats rarely cough due to what kind of disease?
Cardiac
If the animal is in left sided heart failure, the following triad of signs will be present on thoracic radiographs…?
- LA enlargement
- Pulmonary venous distension
- Pulmonary infiltrate (usually predominantly perihilar)
What is seen on a radiograph which indicates bronchial wall thickening?
‘Doughnuts’ and ‘Tramlines’
What are the characteristic changes seen in the airways due to chronic bronchitis?
- Excessive mucus production
- Increased goblet cell numbers
- Hyperplasia or submucosal glands
- Damage to cilia
- Loss of ciliated epithelium
- Squamous metaplasia of mucosa
- Secondary infections
How does chronic bronchitis present?
- Typically small breed / toy breed dogs
- Chronic cough with attempts at production
- Worse on excitement
Describe the prognosis of chronic bronchitis
Prognosis is guarded, since most mucosal changes are not reversible
What is the goal of treatment for chronic bronchitis?
To manage the condition, not to cure
What is the definition of chronic bronchitis?
Coughing for more than 2 of the last 12 months
How is diagnosis of chronic bronchitis confirmed?
Bronchoscopy and bronchoalveolar lavage fluid cytology (+/- bacteriology).
How would a patient with chronic bronchitis present on bronchoscopy?
- Loss of the normal appearance of a glistening mucosal surface
- Thickened mucosa: can be irregular with a cobble-stone appearance
- Excess mucus
Describe the typical cytology of a patient with chronic bronchitis
Mixed inflammatory infiltrate
- pulmonary alveolar macrophages
- neutrophils
- occasional eosinophil
- plasma cells
Describe the general management tips for chronic bronchitis
- Reduce weight if obese
- Avoid stimulating a cough (as vicious cycle): use harness rather than collar / lead
- Avoid irritants e.g. smoky environment
- Keep airways moist
Bronchomalacia is another term for?
Bronchial collapse
Define bronchomalacia
Regional to diffuse dynamic airway collapse of segmental and/or subsegmental bronchi with associated clinical signs due to airflow limitation.
What is chondromalacia?
Bronchial cartilage degeneration
Name the lungworm of dogs
Oslerus osleri
Describe transmission of oslerus osleri
Direct transmission dog/dog, bitch to pups (in respiratory excretions, regurgitant feeding, or via faeces (dirty, environment).
How do oslerus osleri affect the airways?
Produce nodules in the airways e.g. at the bifurcation
What are the presenting signs of a lungworm infection?
Cough and respiratory noise
Name the lungworm of cats
Aelurostrongylus abstrusus
What is the volume used when carrying out a BAL?
0.5ml/Kg
How much of the lavage fluid should you be able to aspirate?
Around 50%
What is the aim of a BAL?
To sample from the most terminal part of the airways as possible
What is normal to see on a BAL cytology?
Ciliated columnar epithelial cells (CCECs)
Goblet cells
Treatment of chronic bronchitis usually involves a combination of which two drugs?
Bronchodilators
Anti-inflammatory glucocorticoids (steroids)
What are the functions of bronchodilators?
- Reduce spasm of lower airways
- Reduce intra-thoracic pressures
- Reduce tendency of large airways to collapse
- Improve diaphragmatic function
- Improves muco-ciliary clearance
- Inhibits mast cell degranulation
What are the functions of glucocorticoids?
- Broncho-dilatory
- Anti-inflammatory
- Inhibit both prostaglandin & leukotriene synthesis
- Potentiate beta-2 adrenergic activity
- Reduce leukocyte accumulation
- Induce lymphopenia & eosinopenia
- Reverse increased vascular permeability
- Alter macrophage function
- Inhibit fibroblast growth
Name the bronchodilator licensed in dogs
Theophylline
When are antibiotics indicated in chronic bronchitis cases?
- Most chronic bronchitis cases do not have bacterial infection as a causal agent
- Secondary infection is possible (e.g. Mycoplasma)
- Antibiotics indicated if C&S results +ve, or if intracellular bacteria seen on BALF cytology
What are the desired traits of antibiotics used for respiratory tract infections?
- Selected based on C + S
- Needs to concentrate in the lung
- Needs to be effective against respiratory pathogens
- Bacteriocidal
- Need to treat for long enough
List some antibiotic options for respiratory tract infections
- Clavulonate potentiated amoxycillin (broad spectrum)
- Cephalexin: mainly effective against G-ve
- TMP sulphonamides (broad spectrum)
- Fluoroquinolones (e.g. Enrofloxacin, Marbofloxacin) (broad spectrum)
- Doxycycline (if confirmed or suspected Mycoplasma or Bordetella)
- Clindamycin: mainly used for G+ve (and anaerobes)
- Metronidazole (anaerobic, some bronchopneumonias)
Describe the antibiotic therapy used for life-threatening pneumonia / bronchopneumonia
Four-quadrant antibiotic treatment
Potentiated amoxicillin, fluoroquinolone, metronidazole
What are the two other names given to describe Eosinophilic lung disease?
Eosinophilic Bronchopneumopathy
Pulmonary Infiltrate with Eosinophils
What is eosinophilic lung disease?
- Spectrum of disease from “chronic bronchitis” to pulmonary granulomatous disease
- Usually a mixture of bronchial and interstitial pulmonary involvement
- Presumed hypersensitivity to inhaled allergens (or parasites e.g. migrating Toxocara canis)
How does eosinophilic lung disease present?
Coughing is the major presenting sign
Also dyspnoeic, exercise intolerant and generally unwell.
Mainly seen in young, large breed dogs
How is eosinophilic lung disease treated?
- Prednisolone
- Immunosuppressive doses usually required
- Taper doses once clinical signs controlled - Wormer to exclude parasitic causes (need to address migrating L3s, so fenbendazole).
- Antibiotics if secondary bacterial infections (not common)
- Bronchodilators (especially if bronchospasm suspected)
What is feline asthma?
Allergic airway disease
or due to reactive bronchoconstriction
Describe the two major manifestations of feline asthma
- Chronic cough. Despite the frequent coughing, cats are not dyspnoeic, and they respond to treatment with glucocorticoids (oral or inhaled).
- Dynamic (reversible) bronchoconstriction (true asthma). Cats may show severe expiratory dyspnoea and distress. They may be severely hypoxic and cyanotic.
Which cats are most at risk of feline asthma?
Indoor
How is feline asthma investigated/diagnosed?
Radiography
Bronchoscopy
BALF cytology
How will feline asthma present on radiography?
- Increased bronchial markings.
- Air-trapping may result in a barrel chest and a flattened diaphragm.
- May have collapse of their right middle lung lobe.
- Chronic asthma with multiple dyspnoeic episodes may have rib fractures evident.
- A pneumothorax may be a sequel in some severe cases.
BALF cytology of feline asthma shows a predominance of?
Eosinophils
Describe the (emergency) treatment of the Dyspnoeic Cat with Feline Asthma
- Minimise stress
- Provide humidified oxygen (in incubator; oxygen cage)
- Give IV steroids (e.g. dexamethasone 1 mg/kg)
- Bronchodilators e.g. Terbutaline (0.01 mg/kg IM or IV)
- Severe, life-threatening distress: Adrenaline
How is feline asthma managed in chronic cases using Metered-dose Inhalers?
- Salbutamol (VentolinR): 1 puff bid or as required, effective within 5 minutes, lasts ~ 4 hours
- Fluticasone (Flixitide): 2 puffs bid, long term control of inflammation, takes 10 – 14 days for peak effect
What are the other methods for management of chronic feline asthma patients
- Try and keep cats away from environmental allergens (e.g. soft furnishings, bedrooms, carpeted rooms etc.).
- Allow cats outdoor access if possible
- Bronchodilators: e.g. Terbutaline
- Prednisolone
How do bronchial foreign body cases present?
- Sudden onset coughing
- Usually gun dog breeds (scenting / sniffing)
- History of exercise through fields / arable crops / woodland
- If long standing, halitosis often marked
- Partial response to antibiotics
