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128 Brachycephalic Airway Syndrome

immunosorbent assay, and polymerase chain referral for respiratory (i.e., ventilator) • Complete recovery can occur spontaneously
reaction) exist but have not replaced the support (p. 1185). in moderately affected animals.
VetBooks.ir • Electrophysiologic testing Chronic Treatment PEARLS & CONSIDERATIONS
mouse test.
Long-term physical rehabilitation, frequent
○ Marked reduction in muscle action
potential amplitude evoked by electrical
stimulation of the motor nerve turning, and soft bedding are essential. Comments
• The index of suspicion for botulism increases
○ Normal or only mildly reduced nerve Nutrition/Diet markedly if more than one animal is affected
conduction velocities Important to meet energy requirements through simultaneously.
○ Normal electromyography balanced nutrition (esophagostomy tube or • Referral may be necessary if long-term
percutaneous endoscopic gastrostomy [PEG] supportive care and ventilatory support are
TREATMENT tube) if the patient is not able to eat voluntarily needed.
(pp. 1106 and 1109)
Treatment Overview Prevention
Treatment consists principally of supportive Behavior/Exercise • Avoid carrion/spoiled food.
care during spontaneous recovery. Passive range-of-motion exercises as well as • Thorough cooking of foods
hydrotherapy in the recovery phase of the ○ Botulinal toxin is destroyed by heating
Acute General Treatment disease to 176°F (80°C) for 30 minutes or 212°F
• Antitoxin (type specific) must be adminis- (100°C) for 10 minutes.
tered before the botulinal toxin binds to Drug Interactions
receptors at the myoneural junction. Avoid aminoglycosides (associated with neu- Technician Tips
○ Type C polyvalent antitoxin (dog) romuscular blockade). • Respiratory watch: monitor for signs of
10,000-15,000 IU/DOG IV or IM, 2 doses distress or increased effort.
given 4 hours apart Possible Complications • Recumbency care is essential.
○ Anaphylaxis (p. 54) is a potential risk; • Aspiration pneumonia
intradermal skin testing (inject 0.1-0.2 mL • Decubital ulcers Client Education
intradermally and assess for wheal 30 • Muscle atrophy and fibrosis • Do not allow pets to roam.
minutes later) is recommended before • Ventilatory failure • If your pet is suspected of eating carrion,
administration. seek immediate veterinary care.
○ Antitoxin may be effective to prevent Recommended Monitoring • Full recovery may or may not occur, and there
further toxin binding if ongoing intestinal • Respiratory rate and character +/− pulse may be permanent neurologic impairment.
absorption/circulation. oximetry or blood gas; temperature and pulse
• Antibiotic use is debated; penicillin and • Chest radiographs SUGGESTED READING
metronidazole have been given to reduce • Serial neurologic examinations Barsanti JA. Botulism. In Greene CE, editor: Infec-
potential intestinal growth of C. botulinum, tious diseases of the dog and cat, ed 4, St. Louis,
but disease occurs due to ingestion of pre- PROGNOSIS & OUTCOME 2012, Elsevier, pp 416-422.
formed toxin.
• Antibiotics if secondary infection (e.g., • Good to guarded AUTHOR: Karen L. Kline, DVM, MS, DACVIM
EDITOR: Karen R. Muñana, DVM, MS, DACVIM
aspiration pneumonia) • Recovery usually occurs 2-3 weeks after
• Hypoxemia due to hypoventilation character- regrowth of terminal motor branches; depends
ized by low PaO2 and high PaCO2 warrants on severity of signs and complications

Brachycephalic Airway Syndrome Client Education
Sheet

BASIC INFORMATION ○ < 6 months of age: signs are usually related GEOGRAPHY AND SEASONALITY
only to stenotic nares Signs of respiratory compromise or distress may
Definition worsen in hot weather.
Narrowing of the upper airway secondary to GENETICS, BREED PREDISPOSITION
selective breeding of aesthetic traits; anatomic • Inherently genetic condition: breeds that ASSOCIATED DISORDERS
and functional abnormalities of the upper airway are affected include shih tzus, pugs, French • Gastrointestinal (GI) disorders (e.g., esopha-
found in brachycephalic (short-nosed) dogs bulldogs, English bulldogs, Pekingeses, gitis, hiatal hernia)
Boston terriers, Cavalier King Charles ○ BAS patients often have signs of GI disease
Synonyms spaniels. (regurgitation, vomiting)
• Brachycephalic obstructive airway syndrome • Cats that are affected include Himalayans, ○ High likelihood of esophageal or gastric
(BOAS) Persians, and British shorthairs. ulceration
• Brachycephalic airway syndrome (BAS) • By definition, Chihuahuas and Yorkshire ter- ○ Severity of GI disease may be correlated
• Brachycephalic syndrome riers are considered brachycephalic, although to severity of respiratory signs
they seem to be less clinically affected. • Pharyngeal collapse, laryngeal collapse
Epidemiology • Urethral prolapse
SPECIES, AGE, SEX RISK FACTORS • Chemodectoma
• Most commonly found in dogs but can occur • Obesity can exacerbate clinical signs. • Macroglossia
in selected breeds of cats. Age at presentation • Heat and exercise can exacerbate clinical • Aspiration pneumonia
varies with severity of anatomic abnormalities. signs. • Epidermoid cyst

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