Upper Respiratory Tract Noise in Companion Animals

M.9, W.3, L.3

List the anatomical causes of obstruction for the following airway spaces:

List the term for abnormally narrow nostrils (common in brachycephalic dogs)

Stenotic nares

list the 6 normal functions of the airways

1. free flow of air into lungs (gas exchange)

2. thermoregulation by panting

3. sense of smell and filtering air (nasal cavity)

4. Phonation (larynx)

5. Protected swallowing (larynx/pharynx)

6. pH balance (CO2 excretion)

List the two classifications of an upper airway obstructions

• Fixed obstruction

• Dynamic obstruction

Define a fixed obstruction

• physical location of narrowing is constant

• intraluminal or extraluminal

• inspiratory and expiratory airflow reduced

What is a dynamic obstruction?

• airway diameter changes based on pressure changes during breathing

• compromised supporting structure of airways

• ± excessive negative pressure on inspiration

List clinical history features of a dog presenting with a URT obstruction

• Exercise intolerance

• cyanosis (severe cases)

• dyspnea

• heat intolerance

• change in phonation

• sleep apnea

What does dyspnoea mean?

difficulty breathing; shortness of breath

list clinical signs of a URT obstruction

Dyspnea, open-mouth breathing, respiratory noises

*examine during/after exercise for diagnosis

Describe STERTOR (definition, localization, typical sign for what disease?)

• Definition:

  • obstructed breathing that produces a snoring/snorting sound

• Localizes to:

  • oro/nasopharynx

• Typical of:

  • Brachycephalic Obstructive Airway Syndrome

Describe STRIDOR (definition, localization, typical sign for what disease?)

• Definition:

  • obstructed breathing causing wheezing

  • harsh or low frequency “roaring” noise

• Localizes to:

  • larynx/trachea

• Typical of:

  • laryngeal paralysis

what noise does a dog make if it presents with tracheal collapse?

goose-honking noise

True or False: the upper airway can’t be examined directly in conscious dogs or cats (only nose)

TRUE

How should the larynx and pharynx be examined for a URT obstruction diagnosis?

Sedation + direct laryngoscopy

How should the nasal cavity be examined for a URT obstruction diagnosis?

• CT

• rhinoscopy

How should the trachea be examined for a URT obstruction diagnosis?

• Radiographs

• CT

• Fluoroscopy

• Endoscopy

What is the etiology of laryngeal paralysis?

• Progressive failure of cricoarytenoideus dorsalis muscles

• failure of arytenoid abduction during inspiration (partial vs. complete)

What nerve is impacted in laryngeal paralysis?

Recurrent laryngeal nerves

What are the clinical signs of laryngeal paralysis?

• Inspiratory stridor

• Dysphonia

• exercise intolerance

• coughing or gagging

• heat intolerance

What does dysphonia mean?

voice disorder caused by raspy, strained voice

How is laryngeal paralysis diagnosed?

Direct observation under light sedation

What does BOAS stand for?

Brachycephalic obstructive airway syndrome

What are the 5 primary abnormalities (congenital) of BOAS?

1. Stenotic nares

2. Long/thick soft palate

3. Hypoplastic trachea (underdeveloped)

4. Aberrant nasal turbinates (abnormal)

5. Macroglossia (big tongue)

What are the secondary abnormalities of BOAS?

1. Laryngeal collapse

2. Bronchial collapse

3. Tonsil eversion

4. Nasopharyngeal collapse

What are the potential gastrointestinal signs of BOAS?

Regurgitation & vomiting

What is tracheal collapse?

Weakening of C-shaped tracheal rings and dorsal membrane

How is tracheal collapse graded?

1 to 4

Which dogs are predisposed to tracheal collapse?

• Middle-aged

• older toy breeds

What are some contributing factors to tracheal collapse?

Obesity, excitement, exercise, heat, airway irritants

How can tracheal collapse be diagnosed?

Radiographs, CT, endoscopy, fluoroscopy

list ways to medically manage URT obstructions in stable patients

• Weight loss

• avoid stress

• avoid high temps

• moderate exercise

• use harness

• medications: steroids, bronchodilators, suppressants

• manage underlying pulmonary disease

list some treatments for patients with URT obstructions that are unstable?

Oxygen therapy, cooling, anti-anxiety medication, fluid therapy, corticosteroids

*last resort = endotracheal intubation followed by surgical intervention

What is the surgical treatment for laryngeal paralysis?

Unilateral cricoarytenoid lateralization (“tie back” cartilage)

What is the surgical treatment for tracheal collapse?

tracheal stent

What are some potential surgical treatments for BOAS?

• Remove excessive tissue - stenotic nares

  • Rhinoplasty

• Removed excessive tissue - overlong soft palate and everted tonsils

  • Staphylectomy (soft palate resection)

  • Tonsillectomy

• Other Procedures

  • laryngeal sacculectomy

  • Laser-assisted turbinectomy

  • Partial laryngectomy

What is a salvage procedure for a URT obstruction if all else fails?

Permanent tracheostomy

What are potential implications of a tracheostomy?

mucus plugs, skin folds, aspiration pneumonia, stoma stenosis, infection