BOAS Flashcards
BOAS =
BRACHYCEPHALIC OBSTRUCTIVE
AIRWAY SYNDROME
Congenital disorder of short-nosed dogs and cats. Structural defects in upper airways.
Increased upper airway resistance causing
Respiratory difficulties, heat intolerance,
and other significant health problems.
Brachycephaly can be calculated with…
Cranio-facial ratio < 0.5 (CFR = A/B)
the ratio of the length of the nose to the length of the head
snout length / skull length
+ Craniofacial angle
BOAS - PATHOPHYSIOLOGY
▪Although the bony skull is reduced in length, the soft tissue structures are not.
▪ Especially nasal turbinates, soft palate, tongue
Extreme brachy cat breeds (2)
Persian, Exotic shorthair
BRACHYCEPHALIC dog BREEDS most commonly affected by BOAS
BOAS - PRIMARY structural PROBLEMS (5)
Stenotic nares
Intranasal airway obstruction (edematous mucosa in the nasal cavity & abnormal Turbinate growth)
Elongated and thickened soft palate
Macroglossia
Tracheal hypoplasia
= Increased airway resistance, reduced airflow, Difficulty in breathing, problems in thermoregulation.
What is “RAT”?
abnormal cranially growing
turbinate structure is obstructing
the nasal cavity (rostral aberrant turbinate = rat)
Describe Tracheal hypoplasia
▪ Congenital malformation that causes
the tracheal diameter to be small.
▪ Ends of tracheal cartilage overlap
▪ C-shaped -> O-shaped (in image, left is abnormal)
Tracheal diameter to the thoracic inlet ratio
▪ < 0.2 in normocephalic dogs
▪ < 0.16 in brachycephalic
▪ < 0.12 in English bulldogs
Secondary changes problems in BOAS. (3)
due to the abnormal airflow, increased negative pressure and obstruction:
laryngeal collapse
Enlarged, everted tonsils
Bronchial collapse
(Especially left cranial bronchus, especially pugs)
Laryngeal collapse grades. (3-4)
normal and grades 1-3
the most severe and most difficult secondary problem in BOAS
Laryngeal collapse
Other problems BOAS can bring on?
Sleep disorders
Heat intolerance
Exercise intolerance
Gastrointestinal problems
Vomiting, regurgitation, dysphagia,
choking attacks
Gastroesophageal reflux, esophagitis, hiatus hernia, gastritis, duodenitis
Problems in skin, eyes, ears, bone structures, teeth, reproduction…
Describe sleep disorders in BOAS animals.
▪ Muscles of the upper respiratory tract relax during sleep leading to worsening of upper respiratory tract obstruction.
▪ Hypopnea/apnea episodes during sleep, waking up, snoring, breathing with a toy in the mouth, tiredness during day-time.
SLEEP APNEA HAS A NEGATIVE EFFECT
ON THE QUALITY OF LIFE!
Most affected breeds for BOAS (3)
▪ Pugs, English and French bulldogs are affected most.
▪ There are Differences in the risk of developing BOAS between breeds and individuals.
▪ Clinical signs start commonly when dogs are young, 1-2 years old, and get gradually worse.
▪ Incidence and prevalence estimates differ between studies.
▪ Cambridge: clinically significant problem in little less than half of English and French bulldogs, and in more than a half of pugs.
Diagnosis of BOAS.
Anamnesis: What kind of noises are heard when the dog is breathing?
▪ Exercise tolerance?
▪ Gastrointestinal signs?
▪ How does the dog sleep?
▪ Heat tolerance? Worse in summer.
▪ Remember other diseases and problems
▪ Look, listen, perform a thorough physical exam.
▪ Evaluate for nasal stenosis
▪ Evaluate respiratory sounds
▪ Stertor – nasopharynx, pharynx, nasal cavity
▪ Stridor – obstructed larynx (pugs)
▪ Auscultate also laryngeal area
▪ Evaluate respiratory pattern
▪ Dyspnea, cyanosis?
▪ Evaluate the dog in rest and after exercise.
Rule out other diagnoses with
▪ Blood samples
▪ Diagnostic imaging
Laryngoscopy to evaluate the soft palate
and laryngeal structures, (esophagoscopy,
nasopharyngeal examination).
BOAS surgery
When BOAS stages 2 and 3.
Involves cutting:
nostrils
soft palate
saccules
tonsils
In anesthesia, use a gastric acid blocket preop, avoid stress, avoid full opioids, use inj. corticosteroids, extubate late in a calm, quiet environment.
