What are the possible causes of an expiratory bark-like cough in a 17‑month‑old child?

Causes of Expiratory Barky Cough in a 17-Month-Old

The most likely cause of an expiratory barky cough in a 17-month-old is viral croup (laryngotracheobronchitis), which typically presents with the characteristic "seal-like" barking cough, inspiratory stridor, and hoarseness due to laryngeal and tracheal inflammation. 1

Primary Diagnosis: Viral Croup

Viral croup is the most common cause of acute upper airway obstruction in children aged 6 months to 6 years, with peak incidence around 23 months of age. 1, 2, 3 The condition is characterized by:

• Barking ("seal-like") cough – the hallmark symptom that allows bedside diagnosis 1
• Inspiratory stridor (though you note expiratory component, both can occur) 3
• Hoarseness due to laryngeal involvement 3
• Low-grade fever and respiratory distress of varying severity 4

Viral Etiology

The causative pathogens include:

• Parainfluenza viruses (types 1-3) – most common cause 1, 2
• Respiratory syncytial virus (RSV) – second most common, found in 28% of croup cases 5
• Human rhinovirus (HRV) – present in 39% of croup cases 5
• Influenza virus – accounts for 11% of cases 5

Important Differential Diagnoses to Consider

While croup is most likely, a barking cough does not rule out other serious airway conditions and you must consider: 1

1. Tracheomalacia or Laryngomalacia

• Can present with barking cough and stridor 1
• Consider if symptoms are recurrent or persistent beyond typical croup duration 4
• Requires flexible bronchoscopy for diagnosis, especially if severe or atypical presentation 1

2. Foreign Body Aspiration

• Must be excluded in any child with sudden onset respiratory symptoms 1
• May present with cough, stridor, and respiratory distress 1
• Key differentiator: typically no viral prodrome, sudden onset while eating or playing 1

3. Bacterial Tracheitis

• Rare but serious complication 1
• Consider if child appears toxic, has high fever, or fails to respond to standard croup treatment 1

4. Recurrent Croup Considerations

If this is a recurrent episode (≥2 episodes per year), consider: 4

• Underlying structural airway abnormality (laryngomalacia, subglottic stenosis) 4
• Asthma – especially if triggered by exercise, irritants, or family history of atopy 1
• Gastroesophageal reflux – if associated with vomiting or feeding difficulties 1

Clinical Assessment Algorithm

Immediately assess for severity indicators: 1

• Ability to speak/cry normally
• Respiratory rate and heart rate
• Presence of stridor at rest
• Use of accessory muscles (tracheal tug, chest wall recession)
• Oxygen saturation
• Life-threatening signs: silent chest, cyanosis, fatigue/exhaustion 1

Note: Agitation may signal hypoxemia rather than anxiety and requires oxygen therapy 1

When Chronic Cough Evaluation is Needed

If the barking cough persists beyond 4 weeks, this becomes chronic cough requiring systematic evaluation: 6

• Obtain chest radiograph 6
• Consider flexible bronchoscopy to evaluate for structural abnormalities 1
• Assess for protracted bacterial bronchitis if wet cough develops 6

Key Clinical Pitfalls to Avoid

• Do not rely on lateral neck radiographs – clinical assessment is more important and radiographs are often unnecessary 1
• Do not perform blind finger sweeps if foreign body suspected – may push object deeper 1
• Do not discharge within 2 hours of nebulized epinephrine due to rebound risk 1
• Do not give over-the-counter cough/cold medications – they provide no benefit and may cause harm 1

Post-Infectious Considerations

If symptoms began after a viral upper respiratory infection:

• Post-viral cough is the most common cause of chronic cough in children in the community 7
• Acute cough typically resolves within 1-3 weeks, but 10% may cough for >20-25 days 7
• Pertussis should be considered if spasmodic cough or known contact, even if fully immunized 7