Small animal bronchial dx

What cough receptors are present in larger vs medium airways? Where are they more numerous?

• Mechanoreceptors – larger airways

• Chemoreceptors – medium airways

More numerous in the URT (larynx, trachea, carina)

What are the Ddxs of coughing?

• Compression of mainstem lobar bronchi

• Stimulation of cough receptors (laryngeal, tracheal, bronchial disorders)

  • Foreign bodies

• Excessive mucus / fluid / inflam (pneumonia, bronchopneumonia, pulmonary oedema)

  • usually soft / moist / ineffectual cough

What can cause compression of mainstem lobar bronchi?

• Left atrial enlargement

• Tracheobronchial / Bronchial LN enlargement

• Neoplasia

How do you differentiate between cardiac or respiratory disease in dogs?

What are the components of the hx needed to investigate a resp dx?

• Environ

• Worming history

• Travel history

• Recent events / illnesses / changes

• Any other signs?

• How long coughing?

• Onset?

• Description of the cough. When worse?

• Is the cough really a cough?

• Any change in voice?

  • e.g. laryngeal disorders

• Does the dog sleep normally?

What are the components of the clin exam for a resp case?

• Observe

  • change in breathing pattern / rate

  • dyspnoea?

  • spontaneous coughing?

• Auscultate all lung areas during non-panting resp

  • crackles (normally on insp) caused by fluid/mucus

  • wheezes caused by bronchial narrowing (e.g. feline asthma / bronchomalacia)

• Listen & palpate URT

• Percussion of thorax

• Thoracic compressibility (cats)

• Attempt to induce cough (tracheal pinch)

  • auscultate following cough

What changes are shown on Rx in chronic bronchitis?

• Thickened bronchial walls

  • Donuts and tramlines

What is chronic bronchitis characterised by?

• excessive mucus production

• incr goblet cell numbers

• hyperplasia of submucosal glands

• damage to cilia

• loss of ciliated ep

• squamous metaplasia of mucosa

• 2° infections common

What is the aetiology of chronic bronchitis?

Aetiology often not known

• Environmental factors

• Previous infection

What is the typical presentation of a chronic bronchitis?

• Typically small breed / toy breed dogs

• Chronic cough with attempts @ production

• Worse on excitement

What is the treatment goal of a chronic bronchitis case?

• Manage as can't cure

  • Guarded prognosis bc most changes not reversible

What investigations are indicated in a suspected chronic bronchitis case?

• Thoracic rads

• Haematology

• Bronchoscopy

• BAL to obtain samples for cytology / bacteriology / parasitology

  • eosinophilia?

How is a bronchoscopy carried out and what should be seen on the sample?

• Anaesthetised animal

• Intubated —> bronchoscope passed down ET tube

• Sample should be turbid, cellular & frothy —> alveoli sampled

What changes are seen on bronchoscopy?

Thickened mucosa, inc mucus, can't see vessels

Right bronchus more obvious, left has more of an angle to get down in normal

What is bronchomalacia?

Bronchial collapse (regional to diffuse) w/ associated clinical signs due to airflow limitation

Can cause wheezy cough & may be 2° to other 1° resp conditions

List the respiratory parasites that may be causing a cough?

• Oslerus osleri

• Crenosoma vulpis (fox lung worm)

• Aelurostrongylus abstrusus (cats)

Describe oslerus osleri infestation

• No inter host

• Direct transmission dog to dog, bitch to pups —> in resp excretions, regurg feeding, faeces (dirty environ)

How does oslerus osleri present on bronchoscopy?

• Nodules at bifurcation

• Worms 5-15mm long

• May have associated airway collapse → cough & resp noise

What could this be?

Crenosoma vulpis (fox lung worm)

• Worms readily seen on tracheobronchoscopy (4-16mm)

• Do not form nodules

What is the inter host of crenosoma vulpis?

Slugs / snails

How do you carry out a BAL?

coupage sides of chest before aspirating fluid again

image first before carrying out BAL

What would you see in normal BAL cytology?

• Ciliated columnar epithelial cells (CCECs)

• Goblet cells

• Look at proportions of cells and if bacteria present esp. if phagocytosed

What are the normal BAL cytology values?

• Normal total WBC < 5 x 10⁹/l

• Macrophages (~ 70%)

• Neutrophils (~20%)

• Lymphocytes (~10%)

• Eosinophils (<20 – 25%)

What is present on a BAL sample if there is oral contamination?

Simonsiella

(non-pathogenic)

How does a BAL sample appear on cytology in a chronic bronchitis case?

• Incr mucus ++

• Incr neutrophils, macrophages

• Possibly squamous metaplasia of normal ciliated columnar epithelial cells (CCECs)

• Presence of bacteria / particulate matter

  • Culture normally -ve

What is important when obtaining a bacteriological culture for chronic bronchitis via BAL?

• Culture normally -ve

• Ensure sample obtained aseptically, avoiding contam from mouth / pharynx

How do you manage chronic bronchitis?

• Weight control

• Harness rather than collar / lead

• Avoid irritants / smoking

• Hydrate so excess mucus is easier to shift

• Avoid very dry environs

• Nebuliser (dogs only)

• Spend time in bathroom during owners shower/ bath

How is chronic bronchitis treated?

• Bronchodilators

• Anti-inflam glucocorticoids (steroids)

• +/- Anti-tussives

What do bronchodilators do?

• Reduce spasm of lower airways

• Reduce intra-thoracic pressures

• Reduce tendency of larger airways to collapse

• Improve diaphragmatic function

• Improves muco-ciliary clearance

• Inhibit mast cell degranulation (reduced     release of mediators of bronchoconstriction)

• Prevent microvascular leakage

Give an example of bronchodilators you can use for chronic bronchitis

• Theophylline (dogs)

• Terbutaline (not licensed for dogs or cats)

What are the effects of glucocorticoids?

• Broncho-dilatory

• Anti-inflam

• 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

• Modulate the immune system

When are ABs indicated for resp dx?

If C&S results +ve or if intracellular bacteria seen on BAL cytology

Can consider tx trial (e.g. doxy in case of mycoplasma)

If sterile NO ABs

What can you add to your tx plan for chronic bronchitis if mucociliary clearance is compromised?

Mucolytic —> e.g. Bromhexine

What can be used as an anti tussive?

• Codeine phosphate

• Diphenoxylate (has atropine so not used if additional heart dx)

Better to treat cause rather than suppress but consider for airway collapse if impacting on quality of life

What is being shown here?

• Bronchopneumonia caused by aspiration pneumonia w/ Mega-oesophagus

  • (Myasthenia gravis —> neuromuscular)

What is being shown here?

Bronchiectasis (thickened bronchi) —> can be end stage of any of the bronchial diseases

• compromised mucocillary clearance → risk of 2° infection

What needs to be considered when choosing an AB for resp dx?

Should be bacteriocidal & needs to be effective against resp pathogens

Need to treat for long enough (2 wks min)

Give examples of an AB you would use for resp infections

• Doxycyline —> if confirmed or suspected Mycoplasma or Bordetella

• Clavulonate —> potentiated amoxycillin (broad spec)

• Cephalexin —> gram -ve

• Fluroquinolones —> broad spc

• Clindamycin —> gram +ve & anaerobes

• Metronidazole —> anaerobic

• Use a combination if life threatening pneumonia/ bronchopneumonia

What is eosinophilic lung disease (ELD)?

• Spectrum of dx from “chronic bronchitis” to pulmonary granulomatous disease

• Usually mixture of bronchial & interstitial pulmonary involvement

• Usually young dogs, large breeds

• Presumed hypersensitivity to inhaled allergens (or parasites e.g. migrating Toxocara canis)

How does ELD usually present on bronchoscopy?

Typically copious amounts of yellow-green mucus

What value is diagnostic for cytology of ELD?

over 25% eosinophils

How is ELD treated?

Prednisolone (2mg/kg/day then slowly tapered once clinical signs controlled)

• (remember to rule out parasites first)

• can consider addition of other immuno-supp agents e.g. azothioprine

What is the most common cause of a cough in cats?

Inflammatory airway disease (IAD)

(also called Allergic Airway Disease or Allergic Bronchitis)

How does feline asthma present?

• Cough

• Can also have bronchoconstriction

  • → air trapping & dyspnoea

  • → expiratory dyspnoea

• Can have exp. wheezes on ausc.

How does feline asthma present on rads?

• Inc bronchial marking (donuts, tramlines)

• If air trapping —> diaphragm flattened, barrel chest on DV view

How do you treat a dyspnoeic cat with feline asthma?

• Minimise stress

• Provide humdified O₂

• Give IV steroids (e.g. dexamethasone 1mg/kg)

• Bronchodilators (terbutaline)

• Consider MDI (meter dose inhaler) admin of salbutamol

• Severe, life threatening —> adrenaline

How can you use the metered dose inhaler (MDI) to manage feline asthma chronically?

• Salbutamol (effective within 5 mins, lasts 4 hrs, give as required)

• Fluticasone (long term control, takes 10-14 days for peak effect)

What general management and oral treatment can be used for feline asthma?

• Keep away from allergens (e.g. soft furnishings, carpet etc.)

• Allow outdoor access to avoid warm, dry environments

• Bronchodilators —> terbutaline / inhaled salbutamol

• Prednis —> consider inhaled fluticasone

• ABs not indicated

How do bronchial FBs present?

• Sudden onset coughing

• Usually gun dog breeds (scenting / sniffing)

• Hx of exercise through fields / crops / woodland

• If long standing, halitosis often marked

• Partial response to ABs