Brachycephalic Airway Syndrome (BAS) in Cats

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Last updated on
5 min read

Key takeaways

Brachycephalic airway syndrome (BAS) is a chronic upper respiratory condition that affects certain cat breeds.

  • Short facial and nasal bones characterize brachycephalic cat breeds; they appear to have a "pushed-in" face
  • The shortness of the skull bones alter the animal's soft tissue structure, which, in turn, can cause breathing problems
  • Symptoms of brachycephalic airway syndrome include breathing through the mouth, exercise intolerance, coughing, and noisy breathing
  • Diagnosis involves physical examination, diagnostic imaging, and examination of the respiratory tract
  • Obesity, allergies, and environmental conditions are contributing factors to the severity of symptoms
  • Treatment focuses on weight reduction and environmental control
  • Surgery is the only way to improve the anatomical abnormalities permanently
  • Prognosis depends on the severity of the anatomical abnormalities and the presence of secondary conditions such as allergies
  • In most cases, with surgical treatment the prognosis is good
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A closer look: Brachycephalic Airway Syndrome (BAS) in Cats

Certain cat breeds are predisposed to brachycephalic airway syndrome, due to having short noses. Common brachycephalic cat breeds include:

  • Persian
  • Exotic shorthair
  • Himalayan
  • Scottish fold
  • Burmese

There are a number of structural abnormalities in the face and upper breathing apparatus which contribute to the development of BAS in brachycephalic breeds, including:

Stenotic nares: Cats with from stenotic nares have excessively narrow and small nostrils.

Elongated soft palate: The softest part of the mouth is too long to fit into the mouth. The excess soft tissue partially blocks the entrance to the trachea.

Hypoplastic trachea: Cats suffering from hypoplastic trachea present a small trachea which reduces the total volume of air passing through the tract with each breath.

Everted laryngeal saccules: The laryngeal saccules (small soft tissue masses found inside the voice box) are turned outwards instead of inwards. Everted laryngeal saccules cause airway flow obstruction.

Enlarged tongue (Macroglossia): impedes flow of air through the mouth.

Frequent medical monitoring, weight management, and early surgical treatment are the best ways to manage Brachycephalic Airway Syndrome.

If the animal requires surgical treatment, sexual alteration (spay/neuter) is also advised to prevent passing the condition to the next generation.

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Risk factors

All brachycephalic cats are at risk of BAS. The severity of the condition depends on how many abnormalities are present and how severely they impact the respiratory structures.

BAS is strongly correlated with obesity, which further exacerbates difficulty breathing and increases the amount of effort required to move leading to higher rates of respiration when not at rest.

Cats with BAS may have anatomical abnormalities, but do not always show symptoms during day-to-day life, depending on how well they compensate. Risk factors for showing symptoms of BAS include:

  • Hot and humid environments
  • Excessive weight
  • Use of neck collars

In some cases, brachycephalic airway syndrome can cause severe oxygen deprivation.

Cats showing signs of oxygen deprivation require emergency veterinary attention to improve oxygenation and prevent life-threatening complications.

Possible causes

Brachycephalic airway syndrome is a genetic condition, which results in a collection of anatomical abnormalities affecting breathing, including:

  • Narrow nostrils
  • Elongated soft palate
  • Enlarged tongue
  • Narrow trachea
  • Turned out laryngeal saccules

Main symptoms

Testing and diagnosis

Diagnosis is based on the animal's breed and clinical presentations.

A cat presenting symptoms of Brachycephalic Airway Syndrome generally undergoes the following diagnostics:

  • Physical examination
  • Diagnostic imaging, such as X-rays or CT scan
  • Laryngoscopy
  • Blood tests: to determine CO2 and pH levels

Steps to Recovery

Once the severity of abnormalities have been characterized through diagnostics, management options include:

  • Weight loss: reducing the animal's body weight reduces the chances of severe symptoms
  • Surgical intervention to correct the anatomical abnormalities

Supplemental oxygen therapy, anti-anxiety medications and anti-inflammatory drugs can be used to stabilize cats presenting in severe respiratory distress.

Diagnosis may require the animal to undergo general anesthesia. Since cats suffering from Brachycephalic Airway Syndrome are at a greater risk of complications caused by anesthesia, corrective surgery is typically performed at the same time as diagnosis.

Brachycephalic Airway Syndrome is a life-long condition. Surgery is the only way to improve the anatomical abnormalities permanently. Early surgical correction is recommended as the condition tends to worsen over time.

With surgical intervention, most cats have a good prognosis. Cats managed with weight loss and avoiding risk factors only have a fair prognosis, as symptoms are likely to worsen over time. Cats with BAS are also at risk of severe complications, such as aspiration pneumonia, heatstroke, and cardiac arrest.


Brachycephalic Airway Syndrome is a chronic, non-contagious condition.

Strategies to reduce the severity of symptoms include:

  • Weight control
  • Using a harness in preference to neck collars
  • Ensuring the animal's environment is not excessively hot and humid
  • Avoid heavy exercise, especially in hot and humid weather

Neutering affected animals is recommended, to prevent the condition from passing to the next generation of cats.

Is Brachycephalic Airway Syndrome (BAS) in Cats common?

Brachycephalic Airway Syndrome only affects Brachycephalic cat breeds. It is common in these breeds.

Typical Treatment

  • Surgery
  • Supplemental oxygen
  • Weight management
  • Environmental controls

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