Chapter 18 - Brachycephalic syndrome

Question 1

List 7 anatomic features that may contribute to BOAS.

Answer 1

1. stenotic nares
2. elongated & thickened soft palate
3. everted laryngeal saccules
4. hypoplastic trachea
5. prominent nasopharyngeal turbinates
6. increased tongue base thickness
7. laryngeal collapse

Question 2

Briefly describe the phenomenon of ‘habituation’ as it applies to PaO2 and PaCO2 in brachycephalic dogs.

Answer 2

Compared to non-brachycephalics, brachycephalics tend to have lower PaO2 and higher PaCO2 at rest. Habituation occurs when the chemoreceptor threshold for PaO2 and PaCO2 is reset to tolerate this without increasing the drive for increased minute ventilation.

Question 3

What is the proposed reason why dogs with BOAS have an increased risk of aspiration?

Answer 3

Chronic upper airway obstruction and greater subatmospheric pleural pressures may lead to disorders of the oesophagus and stomach, increasing incidence of regurgitation and vomiting.

Question 4

Why do sedative and anaesthetic drugs predispose to acute episodes of upper airway obstruction in dogs with BOAS?

Answer 4

These drugs may further weaken upper airway musculature, worsening laryngeal collapse.

Question 5

At what temperature should active warming of hypothermic brachycephalic patients (e.g., after anaesthesia) be discontinued? Why?

Answer 5

99F; hyperthermia should be prevented because it may create a drive for panting that can promote airway collapse.

Question 6

With regards to corticosteroid use following common surgical procedures for BOAS, studies have demonstrated worse outcomes. True/false?

Answer 6

False. No controlled studies have evaluated effect of post-operative corticosteroid use.

Question 7

List 7 abnormal endoscopic findings described in brachycephalic dogs presenting for upper airway disorders.

Answer 7

1. esophagitis
2. hiatal hernia
3. gastroesophageal reflux
4. pyloric hyperplasia
5. gastritis
6. duodenogastric reflux
7. duodenitis