Brachycephalic Obstructive Airway Syndrome (BOAS) in cats

BOAS refers to a group of conditions that result from abnormalities in the body commonly found in flat-faced breeds of cats such as Persian, Himalayan and Exotic short-hair. The health problems seen in cats with brachycephalic syndrome are different from the ones seen in dogs.

BOAS stands for brachycephalic obstructive airway syndrome but can also be called brachycephalic respiratory syndrome. Brachycephalic cats have compacted skeletons that change the shape of their noses, throat, and other body parts. Breathing difficulties are the most common problems that can result from these abnormalities compromising the health and welfare of the cat. As such, severely flat-faced cats should not be bred.

BOAS cat 1 compressed
BOAS cat face shape


What is BOAS in a cat?

BOAS is a combination of signs that impair breathing seen in flat-faced (brachycephalic) breeds of cats.

BOAS is a common cause of upper airway obstruction in dogs, but less so in cats.

When present, it is a lifelong progressive disorder, meaning that it will get worse with time.

These anatomical changes that affect short-nose cats impair airflow through the upper airways (nose, mouth, voice box) and windpipe and contribute to persistent eye discharge.

Cats with brachycephalic syndrome may have:

Respiratory problems

  • Narrowed nostrils
  • Compacted nasal cavities and short nose
  • Bigger nasopharyngeal turbinates (ridges of bones in the nose covered by tissue)
  • Overlong soft palate
  • A tongue that is too big for their mouth, acting as an obstructive barrier to airflow
  • Narrow windpipe
  • Throat problems

Eye problems

  • Protruding eyes with reduced lid closure
  • Persistent eye discharge due to blocked tear ducts

Dental/mouth problems

  • Teeth are not aligned properly when the jaws are closed, leading to dental disease

Excessive skin

  • Excessive skin folds on the face contribute to narrower nostrils and make them prone to skin infections


The symptoms of BOAS can be subtle, but the condition can be very serious.

It is very important that you discuss the severity of your cat’s facial conformation and any symptoms that you have noticed with a vet.



Symptoms of BOAS in cats

The signs of BOAS are varied and can range in severity, including some or all of the following:

  • Difficulty breathing
  • Loud, raspy respiratory sounds
  • Snorting
  • Snoring
  • Nasal discharge
  • Sneezing
  • Worsening signs in hot or humid weather
  • Eye discharge



Are some cats more at risk of BOAS than others?

Having severe breathing problems can be life-threatening. The higher the risk factor, the shorter your cat’s life expectancy.

The main risk factors are:

  • Being a brachycephalic breed: Persian, Himalayan, and exotic short-hair.
  • The severity of the physical defects
  • Being overweight
  • Older age
BOAS cats 2 compressed
Normal cat head shape on top. BOAS cat head shape at the bottom.


How will my vet know if my cat has BOAS?

Your vet will assess your cat’s facial shape and behaviour in certain circumstances. They will also carry out:

  • Physical and visual examinations
  • Heavy sedation or full anaesthesia
  • Rhinoscopy (exam of the inside of the nose)
  • X-rays and/or CT scans


Vet treatment

What treatment options are available for BOAS in cats?

The main treatments include weight control and surgery.

Will your cat need BOAS surgery?

Surgical procedures can include:

  • Widening of the nostrils
  • Reducing the length of the soft palate
  • Removing excessive and/or everted laryngeal tissue

Your veterinarian might recommend one or more of the above, based on your cat’s specific needs. In some cases, referral to a board-certified surgeon is recommended.

Even with surgery, brachycephalic animals’ airways will never be completely normal.

Are there any medical treatment options for cats with BOAS?

  • Weight control
  • Medication to reduce inflammation
  • Antibiotics to treat secondary respiratory infections


Home treatment

How to help your cat with BOAS at home?

  • Keep your cat slim: Monitor their food and body condition score (BCS). Carrying extra weight will make any breathing problems worse.

Body Condition Score (BCS) is a scale that gives a practical evaluation of the fat coverage of your cat’s body. By checking how easy or not it is to feel certain bony areas of the body, a score is then produced. There are several scales, from 1 to 5 or 1 to 9. The ideal body condition lies in the middle, so either 3/5 or 5/9.

The body areas normally checked for fat coverage are:

1. ribs and spine

2. hips and shoulders

3. waist

Body condition scoring (BCS) in cats

Here are a few tips on how to do it.

With your pet in a standing position:

  • Place your hands on the rib cage and gently feel for each rib, without pressing too hard
  • Feel the waist and look from the top and the side (if you have a very furry breed, it may be harder to assess)
  • Feel the spine, which runs down the middle of the back
  • Feel the top of the hips and shoulders


  • During hot/humid weather: Keep your cat indoors with air conditioning, when possible, and restrict exercise.
  • Reduce any respiratory irritants in the home, such as smoke, dust, mould and potentially air fresheners.
  • Reduce stress: Cats are very sensitive to stress, which can lead to a worsening of their BOAS signs.


What is the overall outlook for your cat?

The prognosis for cats with BOAS depends on how many physical problems are present and how old your cat is at the time of diagnosis and treatment.

To maintain quality of life, vet visits should be done regularly to monitor new symptoms or to see if any worsen.



How can you prevent or minimize the signs of BOAS in cats?

Responsible breeding: cats with significant breathing difficulty or those that need surgery should not be used for breeding. It is usually recommended that these animals be neutered at the same time that surgical correction is performed.

Ongoing care: to reduce the severity and frequency of BOAS symptoms follow the previous recommendations on diet, exercise, and environmental modifications.


When to worry

When to worry if your cat has BOAS?

Seek immediate assistance from an emergency vet practice if your cat:

  • Struggles to breathe or is open-mouth breathing (cats do not pant, this is an emergency)
  • Gums become blue or grey
  • Collapses

At Joii we can help:

  • If you are thinking about getting a flat-faced breed cat
  • Assess your cat’s weight or help them lose it
  • Check if your cat has any symptoms of BOAS


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