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Educating the Veterinary Students of Tomorrow

Brachycephalic Obstructive Airway Disorder (BOAS)

The term brachycephalic (pronounced ‘brackee-cefalic’) in dogs refers to those with a flat and wide skull shape. These dogs have a severely compressed face from front to back and can appear that they have no nose present at all (McAlinden, 2012). Common brachycephalic breeds include the Pekingese, pug, bulldog, Chihuahua and Shih Tzu (PetMD, 2017). These breeds tend to appeal to people because of their big ‘puppy dog’ eyes and human baby-like expression, as well as making fun companions. These breeds have been selectively bred over many generations, resulting in drastically shortened upper jaws (Blue Cross, 2017).

There is clear evidence of the flattening of the Bulldog’s skull over the last half century. When comparing today’s English Bulldog skull to that of 50 years ago, there is a dramatic change. Their skull is shorter with no obvious nose and their eye sockets have become shallower, causing the eyeball to significantly protrude, posing a greater risk for direct trauma to the eye or potential ulceration (McAlinden, 2012).


                                      Evolution of the English Bulldog: 50 years ago til today
 







                               http://www.theveterinaryexpert.com/wp-content/uploads/2012/11/change-in-shape-of-the-bull-dog-skull.jpg

 The Kennel Club have reported a 2,747% rise in French Bulldogs registered since 2004 but a survery by the Royal Veterinary College found 58% of brachycephalic dog owners did not recognise the signs that their dog was struggling to breathe (Blue Cross, 2017). This increase in popularity of brachycephalic dogs is increasing animal suffering simply due to the result of intense, selective breeding for this unnatural appearance (BBC, 2016).

Many of these dogs suffer from a breathing disorder called ‘Brachycephalic Obstructive Airway Syndrome’ (BOAS), a lifelong disorder impairing their ability to breathe due to narrowed nostrils and an elongated soft palate, obstructing the passage of air through the nose and throat. There is also evidence of tracheal narrowing in some breeds such as the Bulldog (PetMD, 2017). Many of these dogs have a history of noisy breathing, especially upon inspiration (ACVS, 2017). Characteristics reported in nearly 100% of cases of dogs with BOAS is an elongated soft palate and a narrowed nasal passage is reported in about 50% (PetMD, 2017).

Dogs with BOAS can struggle to sleep normally and tend to snore, occasionally suddenly waking due to brief periods where their breathing stops. In extreme cases there can be evidence of a blue or grey tinge to their gums and tongue, indicating low blood oxygen, which can cause collapse due to oxygen deficiency (hypoxaemia). Some may also show problems with their gastrointestinal system by regurgitating, vomiting and coughing up foamy saliva (The Kennel Club, 2017).

Major risk factors for BOAS include a high body condition score (BCS) and obesity, as this puts excess pressure on their already compromised respiratory system (The Kennel Club, 2017). Warm and humid weather can also worsen BOAS (PetMD, 2017).

In extreme cases, corrective surgery can ease the common symptoms seen with BOAS (The Kennel Club, 2017). Elongated soft palates can extend past the tip of the epiglottis (entrance to the airway) and in severe cases can extend directly into the laryngeal opening. This can cause inflammation and reddening of the tip of the soft palate and edges of the larynx (ACVS, 2017). Excessive soft palate can be trimmed, nostrils can be widened and collapsed parts of the larynx can be removed (The Kennel Club, 2017). The prognosis is good for young animals, reducing respiratory effort and distress. It can also significantly improve their activity levels (ACVS, 2017).

Despite their shortened upper jaw, brachycephalics still have the same number of teeth as those with longer snouts (adult dogs have 42 teeth). These teeth have to fit into a much smaller area causing overlap and an increased risk of decay and gum disease. Excess skin around the upper jaw creates deep skin folds around their eyes and nose which can predispose to very sore skin infections from poor ventilation. Shallow eye sockets also cause their eyes to protrude much more than longer-muzzled breeds. Tear film does not spread properly over the entire surface of the eye leaving them vulnerable to injury or corneal ulcers, easily resulting in loss of an eye if left untreated.
High numbers of brachycephalic breeds struggle to give birth naturally as selective breeding has caused disproportion between the size of the mothers’ birth canal and the puppies’ large heads. This condition is called ‘dystocia due to foetal-pelvic disproportion’. 85% of English Bulldog puppies and over 80% of French Bulldog puppies are delivered by caesarean section in the UK (Blue Cross, 2017).


For more information, see the websites below:


https://www.fitzpatrickreferrals.co.uk/soft-tissue-service/brachycephalic-syndrome/

http://www.dogbreedhealth.com/brachycephalic-obstructive-airway-syndrome/

http://mrcvs.co.uk/en/news/15608/



 REFERENCES 


ACVS. (2017) ‘Brachycephalic Syndrome’ [online] Available at: https://www.acvs.org/small-animal/brachycephalic-syndrome [Accessed: 01/11/17].

BBC. (2016) ‘Vets warn people against buying ‘flat-faced’ dogs’ [online] Available at: http://www.bbc.co.uk/news/uk-37423040 [Accessed: 01/11/17].

Blue Cross. (2017) ‘Things to think about before buying a flat-faced dog’ [online] Available at: https://www.bluecross.org.uk/pet-advice/things-think-about-buying-flat-faced-dog [Accessed: 01/11/17].

The Kennel Club. (2017) ‘Breathing problems in brachycephalic dogs’ [online] Available at: https://www.thekennelclub.org.uk/health/for-owners/brachycephalic-health/breathing-problems-in-brachycephalic-dogs/ [Accessed: 01/11/17].

McAlinden, A. (2012) ‘What is a brachycephalic dog?’ [online] Available at: http://www.theveterinaryexpert.com/nose-and-throat/brachycephalic-dog/ [Accessed: 01/11/17].

PetMD. (2017) ‘Breathing problem in short-nose breed dogs’ [online] Available at: http://www.petmd.com/dog/conditions/respiratory/c_multi_brachycephalic_airway_syndrome?page=show [Accessed: 01/11/17].