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Brachycephalic Obstructive Airway Syndrome (BOAS) 

WHAT IS A BRACHYCEPHALIC?

Brachycephalic animals are those with shortened upper jaws and noses. Typical breeds include: English Bulldog, French Bulldog, Pug, Lhasa Apso, Shih Tzu and Pekingese.
 
WHAT IS BRACHYCEPHALIC OBSTRUCTIVE AIRWAY SYNDROME (BOAS)? 

Brachycephalic obstructive airway syndrome is the term used to describe the effect that shortening of the jaws has on breathing and airway resistance. In brachycephalic breeds the soft tissues of the head are crammed together due to lack of space leaving less room for airflow. Animals with BOAS often produce a lot of upper respiratory noise, varying in severity from snorting/snoring to severe respiratory distress.  

Dogs with BOAS may have severe welfare problems, even mildly affected dogs are likely to suffer from disrupted sleep and are often unable to exercise, play or eat normally due to their compromised breathing, especially in hot weather where they easily overheat. BOAS will often develop age with younger dogs showing fewer signs.

Recent research has shown that the shorter the   muzzle length relative to skull size, the more likely the dog is to suffer from BOAS. Obesity and a thick neck also increase the risk. Practical steps to take when buying a high risk breed are to buy puppies from parents with longer muzzles and slimmer necks. 

When buying a brachycephalic puppy you should avoid purchasing any dog showing signs of     breathing compromise, or whose parents either have problems or have had surgery to correct those   problems. Sadly, due to the increased demand, there has been a surge in the number of high risk breeds being bred and illegally imported from Europe.

WHAT SIGNS MIGHT MY DOG SHOW? 

  • Frequent or lasting shortness of breath/panting 
  • Difficulties in exercise (walking, running and playing) due to breathlessness 
  • A tendency to overheat 
  • Respiratory noises such as snorting and snoring, when both asleep and awake 
  • Laboured or exaggerated breathing 
  • Frequent vomiting, regurgitation or retching of froth 
  • Disturbed sleep from sleep apnoea 
  • Narrow slit-like nostrils 
  • Brachycephalic breeds also frequently have skin fold infections, spine and limb abnormalities and eye problems. 

WHY DO I SEE THESE SIGNS? 

Narrowed nostrils can dramatically increase resistance to air flow meaning that normal breathing requires a greater effort – try breathing through a straw or through your nose when you have a cold. 

An overlong soft palate can also partially obstruct air flow  which both further increases the amount of effort required for an affected animal to breathe, and causes significant  inflammation of the upper airway. 

The extra effort required to breathe frequently results in secondary problems including: 

Gradual collapse of the larynx (voice-box) termed laryngeal collapse. The severity of collapse is graded from 1 to 3, with 3 being the most severe. Unfortunately, laryngeal collapse is likely to be         progressive, although it may be possible to slow the rate of progression with  appropriate treatment. 

Acid reflux from the stomach into the oesophagus (food pipe) causing inflammation of the oesophagus and sometimes stomach ulcers. Severe cases may suffer from a hiatal hernia, when part of the stomach can become displaced into the chest cavity during breathing. 

HOW IS BOAS DIAGNOSED? 

Without a general anaesthetic, assessment is limited to the nostrils. A full assessment requires an examination under general anaesthesia to confirm the  diagnosis and which surgeries will be required. There are a number of tests that may be recommended, depending on the findings of the initial examination. These can include blood tests, cardiac assessment and chest x-rays.  
  
WHAT TREATMENT OPTIONS ARE AVAILABLE? 

Any procedure which improves air flow will reduce the effort required to breathe. Surgery therefore is aimed at improving airflow. 

Stenotic Nares (narrowed nostrils). Nostrils can be widened by removing of a section of the nose to improve the airflow. 

Overlong Soft Palate. An excessively long soft palate can be shortened in order to reduce the interference with air flow into the larynx. 

Laryngeal Collapse. Early laryngeal collapse can sometimes be improved by removal of some of the tissue that is slowing airflow.  

Dogs with severe (Grade 3) collapse are unlikely to benefit greatly from a minor procedure and may require specialist surgery. Our aim is to identify dogs with early disease and prevent or delay the onset of grade 3 disease. 

Acid reflux. Treatment for gastric reflux usually   involves regular medication, rather like one might take for heartburn. 

Weight management. The lifestyle of many of these patients can predispose them to obesity. Weight loss can dramatically improve the airflow through the pharynx and neck and is an important part of the treatment protocol in overweight patients.

WHAT IS THE PROGNOSIS? 

Most dogs suffering from clinical signs of BOAS that receive prompt, appropriate treatment           experience a significant improvement in exercise tolerance and ease of breathing. However, due to the fact that the surgeon can never create a completely normal airway for brachycephalic animals, they remain susceptible to heat stress and many are unable to exercise to a level that one might expect from animals with more normal head conformation.

It is generally hoped that surgery to the nares, soft palate and the larynx will slow the onset of laryngeal collapse by improving the airflow and reducing the negative pressures developed during respiration. Early surgery, carried out   before the laryngeal collapse has become severe, should maximise the benefit from surgery and reduce the risks of significant laryngeal collapse later in life. 

Unfortunately, despite treatment, laryngeal collapse can reach a critical level in some cases and may require further surgery at some point in the future. However, many dogs do not experience significant further deterioration during their lifetime and therefore never require additional surgery.

General anaesthesia in brachycephalic dogs can be associated with increased risk, particularly    during the induction and recovery phases and    despite the many precautions taken, the risk of the general anaesthetic and complications from airway surgery can never be eliminated. We are aware of the special needs of brachycephalic patients undergoing these procedures, and do our best to minimise complications with the aim to enabling your dog to lead a happy life with improved respiratory function. 

If your dog has required surgery for BOAS, we advise against breeding from him/her in future. If your dog is pedigree, we are obliged to inform the Kennel Club of any conformation altering surgical procedures.

We recommend neutering alongside airway improvement surgery to reduce the breeding of more dogs with respiratory problems.

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