Respiratory Noise in Dogs

Overview of Respiratory Noises in Dogs

Dogs can have respiratory problems that cause respiratory noises. A respiratory noise is an abnormally loud sound that results from air passing through an abnormally narrowed pharynx (throat) or larynx (the upper part of the windpipe) as a result of increased resistance arising from a partial blockage to these regions.

The most common respiratory noises described are:

• Stertor – a low-pitched snoring sound arising from the vibration of soft/weak tissue or fluid
• Stridor – a high-pitched sound arising from the vibration of rigid tissue by the passage of air

General Causes of Canine Respiratory Noises

• Brachycephalic syndrome. This is a combination of disorders seen in short nosed wide headed breeds.
• Laryngeal paralysis. This is impaired function of the muscles of the upper windpipe/voice box.
• Airway tumors/middle ear polyps (benign growths)
• Anesthesia/sedation
• Acromegaly. This is an abnormal enlargement of the extremities caused by an overproduction of growth hormone.
• Neuromuscular dysfunction. This is abnormal function of the nervous/muscular systems, such as Myasthenia gravis, polyneuropathy, polymyopathy, hypothyroidism.
• Inflammation or edema (abnormal fluid accumulation) of the palate, pharynx or larynx secondary to coughing, vomiting, upper respiratory infections, hemorrhage or foreign bodies

What to Watch For

• Increased respiratory effort
• Distress
• Blue color to the mucus membranes
• Collapse

Diagnosis of Respiratory Noise

A thorough history and physical examination can help determine the underlying cause of the respiratory noise and help decide which tests are necessary. Some tests may include:

• Baseline blood tests to include a complete blood count (CBC), biochemical profile and urinalysis
• Visual oral inspection/examination may be diagnostic in some cases (certain foreign bodies, laryngeal paralysis).
• Radiographs (x-rays) of the head and neck in cases with masses or foreign bodies
• Dynamic (in motion) fluoroscopy (a type of radiographic evaluation) to assess the function of the throat and trachea (windpipe)
• Pharyngoscopy/laryngoscopy or directly visualizing these structures with the aid of a scope

Treatment of Respiratory Noise

Your veterinarian might recommend several things to treat the patient with respiratory noise symptomatically, prior to instituting a full diagnostic work up. Medical approaches to individuals with respiratory noise are only appropriate for the cases that are secondary to infection, inflammation, edema or hemorrhage. Anatomic (structural) or neurologic causes are usually not amenable to symptomatic medical treatment.

• Keep the patient cool, quiet and calm
• Oxygen therapy and/or surgical intervention may be indicated in some cases
• Anti-inflammatory drugs or diuretics may be indicated depending on the underlying cause, and should only be used as directed by your veterinarian

Home Care and Prevention

A patient with respiratory noise can make the transition from a noisy breather to a patient who has a blocked airway and warrants emergency therapy in seconds. Some of these patients must be monitored continually.

Remove any possible exacerbating (worsening) circumstances to include excessive exercise, high environmental temperatures, and extreme stress or excitement.