BOAS: Pathophysiology and Recognition Flashcards
Define brachycephalic.
Shortened skull length to width (width > 80% of length) results in both nasal cavity and pharyngeal compression
With the skull index definition, what breeds are brachycephalic? (13)
Pug,
French Bulldog,
English Bulldog,
Boston Terrier,
Cavalier King Charles Spaniel,
Pekingese,
Japanese Chin,
Dogue de Bordeaux,
Shih-tzu,
Boxer,
Pomeranian,
Griffon,
Lhasa Apso.
Unfortunately, breeding for a particular phenotype (the wide head and flat muzzle) has resulted in accompanying diseases (7)
upper airway obstruction,
skin folds = pyoderma, shallow orbits with protruding globes = corneal ulceration and globe prolapse,
dental overcrowding
malocclusion
hemi vertebrae
Risk factors for BOAS (6)
Breed
Age
Nostril status
Body condition score
Gender (breed specific)
Conformation-breed specific
BOAS is a progressive disease and dogs usually present with BOAS at what age
between 1 and 4 years
How does the neck relate to BOAS?
Neck girth is another risk factor for BOAS
BOAS; what sex in pugs are more likely?
Female
BOAS; what sex in bulldogs are more likely?
Male
Other than nostrils, what external conformational factors in pugs effect BOAS? (2)
wider head
wider set eyes
Other than nostrils, what external conformational factors in English bulldog effect BOAS? (2)
width of head
thick neck
Other than nostrils, what external conformational factors in French bulldog effect BOAS? (2)
short neck length
shorted muzzle.
The turbinates are bony structures covered by mucous membranes, these membranes serve to ? (2)
warm and humidify the air before it moves to the lung
After turbinates where does air pass before going through the back of the mouth, and into the larynx to enter the trachea?
The air then passes over the soft palate,
When the dog is excited or exercising, nasal breathing will switch to open-mouth breathing. Why?
Increase the efficiency of inspiration and reduce heat by panting.
Brachycephalic dogs have a shortened skull and muzzle, the hypothesis is that?
is due to premature closing of the sutures at the base of the skull.
What causes restricted air flow in BOAS?
Increased soft tissue in the pharynx and nasal cavity
The lesion sites that are linked to BOAS include (7)
stenotic nares,
thickened + long soft palate,
hypoplastic trachea,
compressed nasopharynx
bronchial collapse,
hyperplastic tongue
excessive turbinate crowding in the nasal cavity
BOAS lesions can cause secondary areas of collapse and inflammation, such as (3)
laryngeal collapse,
laryngeal ventricle eversion
tonsillar hypertrophy.
Increased thoracic pressures in BOAS may result in:
(6)
pulmonary hypertension
cor pulmonale
reflux
Hiatal hernia
Aspiration pneumonia
Nasal Grading System; when to assess nostril mobility?
After exercise
Nasal Grading System; define grade 0
Clear space dorsally between lateral nasal wing and philtrum, usually mobile.
Nasal Grading System; define grade 1
Mild stenosis - clear but small gap between nasal wing and philtrum, usually mobile.
Nasal Grading System; define grade 2
Nasal wing touches philtrum dorsally, often immobile.
Nasal Grading System; define grade 3
No hole in nostril - dorsally or ventrally, immobile.
Grade 2-3 nasal grading, increases BOAS risk by how much?
4x
What is the effect of an elongated soft palate on breathing ability?
trap the epiglottis of the larynx making it difficult to switch from nasal breathing to open mouth breathing.
if the dog struggles to breathe, how can this further impede airflow?
Soft palate and surrounding tissues can become quite swollen and oedematous
3 stages of laryngeal collapse
1 Everted laryngeal ventricles
2 Deviation of the cuneiform cartilage medially
3 Medial collapse of the cuneiform and corniculate cartilage of the arytenoid obstructing the airway
Which is the most common stage of laryngeal collapse, seen in 50% of cases?
Everted laryngeal ventricles
Where do Laryngeal ventricles (or saccules) sit?
In the larynx, between the vestibular and vocal folds
Laryngeal ventricle lies medial to the A) cartilage and lateral to the B) (2)
A) thyroid
B) vocal and vestibular folds
CARE - remember that static images on endoscopy, radiography or CT may be affected by (4)
endotracheal tube,
phase of respiration,
head position
degree of mouth opening
BOAS primary lesions (6)
- Stenotic nares
- Elongated/thickened soft palates
- Macroglossia
- Reduction in the nasopharyngeal area
- An obstructed nasal cavity
- Tracheal hypoplasia
BOAS secondary factors (5)
- Laryngeal Collapse (8-53%)
- Tonsillar hypertrophy
- Hiatal hernia
- Oesophagitis
- Pulmonary hypertension
The upper airway obstruction may manifest as (7)
respiratory noise,
dyspnoea,
exercise intolerance,
heat sensitivity,
sleep disorders,
cyanosis,
collapse
BOAS GI signs? (4)
Regurg
V+
Oesophagitits
Reflux
Which of the following is not important when assessing nostrils?
Any skin flaring behind the nostril
The ventral space
The dorsal space
The ventral space
Some dogs, particularly what breed, that appear to have reasonable respiratory function until stressed or exercised when they then show marked dyspnoea. Clinical signs are exacerbated by heat and exercise.
Pugs
Respiratory functional grading; how long do we exercise?
3 mins
Respiratory functional grading; what is noted? (4)
refusals,
airway noise,
effort,
extreme respiratory signs pre- and post-exercise
Define Respiratory functional grading; Grade 0
Not present
Define Respiratory functional grading; Grade 1
Mild (only audible with a stethoscope)
Define Respiratory functional grading; Grade 2
Moderate (intermittent and heard without a stethoscope)
Define Respiratory functional grading; Grade 3
Severe (easily audible without a stethoscope and constant)
What is Respiratory functional grading assessing?
Airway noise
Any dog that is severely affected at rest should not be exercised! What grade are they?
3
Respiratory functional grading; where do we auscultate these patients?
directly over the larynx, with the stethoscope held gently against the side of the larynx
What 2 sounds are we listening for with Respiratory functional grading and what do they mean?
- stertor- the soft palate vibrating (too long or because the nasal cavity is obstructed.
- stridor; larynx is collapsing due to high pressures when breathing in
Laryngeal collapse is more common in which BOAS breed?
Pug
Stertor is best described as a low-pitched noise most likely originating from the:
nasopharynx
Which Respiratory functional grading is “clinically unaffected”
0 and 1
Which Respiratory functional grading is “clinically affected”
2 and 3
what Respiratory functional grading are surgical candidates?
3
What does a grade 2 Respiratory functional grading mean in terms of surgery?
likely surgical candidates but if obese, weight loss could be initiated prior to surgery.
What else can we use the grading system for in addition to our objective respiratory function test?
Monitoring
The Respiratory Functional Grading Scheme (RFG Scheme) was launched by?
Kennel Club/University of Cambridge i
Other than using RFG. Other signs of nasal obstruction (3)
- flaring of the skin just behind the nasal planum,
- lack of nasal wing mobility
- excessive panting on the edge of obstruction .
How does whole body barometric plethysmography (WBBP) happen?
dogs are placed in a sealed chamber with biased airflow moving across it.
What parameters are measured with whole body barometric plethysmography (WBBP)(7)
breathing frequency;
total inspiratory volume,
insp time and peak flow;
total expiratory volume,
Exp time and peak flow;
lags between breath cycles (if any)
minute respiration volume.
How many dogs dont give a usable result with whole body barometric plethysmography (WBBP)?
Why (3)
10 - 20%
- Pant, bark, move
Why is BOAS index important?
bjective measurement with which to evaluate risk factors for BOAS and the effectiveness of our surgical treatments, looking at the whole upper airway rather than individual sections.
What BOAS index “should be” bred?
0, 1, 2
