Brachycephalic Airway Obstruction Syndrome in Flat-Faced Dogs
Many people are not familiar with the term brachycephalic, but if you own a Pug, Boston Terrier, Pekingese, Boxer, French or English Bulldog, Shih Tzu, or any one of the other breeds with pushed-in or short faces, you should become familiar with this word. The word comes from the Greek roots brachy, meaning short, and cephalic, meaning head.
Brachycephalic dogs have been bred to possess a normal lower jaw that is in proportion to their body size and a compressed upper jaw. In producing this cosmetic appearance, we have compromised these animals in many important ways, and you as an owner must be familiar with the needs and limitations of your pet.
The Respiratory System and Brachycephalic Obstructive Airway Syndrome (BOAS)
Brachycephalic breeds make a lot of snorting and snoring respiratory sounds as a matter of course simply because of the way their throats and faces are shaped. These sounds are the consequences of a combination of several anatomic deformities described below. These deformities occur to varying degrees of severity. Most brachycephalic dogs are not severely hampered by their anatomy on a day-to-day basis but they do have limitations that must be recognized. Severely affected individuals require early and sometimes repeat surgical intervention.
Stenotic Nares
This is a fancy name for narrowed nostrils. The brachycephalic dog’s respiratory passage begins with very small, often slit-like, nasal openings for breathing. This leads to a great deal of open-mouth breathing and panting as the nasal breathing route is limited by its small opening. In selecting a puppy for adoption, it is a good idea to look at the nostril sizes on each member of the litter and look for the widest opening. Stenotic nares can be surgically corrected after about 5 months of age and during the same anesthesia for spay or neutering.
Enlarged Tongue (Macroglossa)
The brachycephalic dog’s tongue can be particularly thick and large, which contributes to overall obstruction in the back of the throat. The French and English bulldogs seem particularly predisposed to this issue.
Elongated Soft Palate
It is difficult to fit the soft tissues of the canine mouth and throat into the brachycephalic’s short face. As a result, the soft palate, which separates the nasal passage from the oral cavity, flaps loosely down into the throat, creating a sort of curtain that vibrates and moves during breathing and results in snorting sounds, called stertor. Virtually all brachycephalics suffer from this but actual respiratory distress is not common, except in English Bulldogs. The English Bulldog tends to have more severe symptoms in almost all aspects of brachycephalic syndrome. Excess barking or panting may lead to swelling in the throat which can, in turn, lead to trouble. Again, the soft palate can be surgically trimmed.
Tracheal Stenosis/Hypoplastic Trachea
The trachea is also known as the windpipe. The brachycephalic dog’s windpipe may be dangerously narrow. This condition creates tremendous anesthetic risk and should be planned for prior to any surgical procedures as anesthetic safety depends on the placement of a tube in the windpipe to secure air passage. The English bulldog is particularly affected by this anatomical defect.
Everted Laryngeal Saccules
The normal larynx has two small pockets called ventricles or saccules. When a dog has increased effort to breathe, over time these little pockets will actually turn inside out inside the throat. When this occurs, it obstructs the airway. This condition can be corrected surgically; however, in many cases, it resolves on its own after the stenotic nares are corrected so surgery is generally only performed in severe situations. The pug is especially predisposed to this situation.
Heat Stress, Excitement, and Exercise
Because of all these upper respiratory obstructions, the brachycephalic dog pants inefficiently. A dog with a more conventional face and throat can pass air quickly over the tongue through panting. Saliva evaporates from the tongue as air passes across and the blood circulating through the tongue is efficiently cooled and circulated back to the rest of the body.
In brachycephalic dogs, so much extra work is required to move the same amount of air that the airways become inflamed and swollen. This inflammation leads to more severe obstruction, distress and further overheating, which is potentially life-threatening. It should always be a consideration during stressful situations, especially air travel and in warmer weather. The American College of Veterinary Surgeons has further information on brachycephalic obstructive airway syndrome.
Brachycephalic dogs are the most likely candidates for heat stroke.
Altogether, the upper airways of the brachycephalic dog compromise the ability to take in air. Under room temperature conditions with low humidity, the compromise is not great enough to cause a problem; however, an owner should take care not to let the dog become grossly overweight or get too hot in the summer. These dogs should not be out for long periods when the ambient air temperature is higher than 80F or if the humidity level is above 50%. They should NEVER be left outside in the spring/summer/fall. Be aware of what degree of snorting and snoring is usual for your pet and take action to remove your dog from overly warm conditions or to stop exertional activity and cool your dog. If heavy, uncontrolled panting or collapse is noted – seek veterinary emergency care immediately. Anesthetic risk is higher than usual in these breeds, though under most circumstances the necessary extra precautions are readily managed at our hospital.
To be clear, brachycephalic syndrome is typically progressive, especially if it is not corrected at an early stage. Severely affected dogs can experience collapse of the larynx and require permanent tracheostomy (a hole in the throat for breathing). Animals with permanent tracheostomies are at high risk for sudden death.
Gastrointestinal Tract
There appears to be a constellation of stomach and swallowing issues that correlate to the respiratory obstruction. In brachycephalic breeds, the esophagus (the tube that conducts swallowed food from the throat to the stomach) experiences reflux of stomach contents. This reflux generates pain and inflammation. Compounding this problem is the retention of food in the stomach for prolonged periods. Pooling of food in the stomach creates a sensation of nausea and increases the potential for vomiting and/or stomach acid reflux. The English and French bulldogs seems particularly predisposed to this associated GI disease. This sounds like a separate issue from upper airway obstruction, but in fact, the reflux, regurgitation and even herniation of part of the stomach into the chest cavity has been postulated to result from the extreme inhalation efforts made against the upper airway obstruction that comes from the shape of the brachycephalic head. Medications are helpful for GI issues as is weight control, but often correcting the respiratory obstruction helps correct the intestinal problems as well.
Eye Problems
With most of the nasal bones compacted, brachycephalic dogs tend to have trouble with the way their eyes sit in their heads. The eye sockets are shallow making the eyes especially prominent and vulnerable. Often a nasal fold of skin rubs on the eyeball and/or there are eyelashes rubbing on the eye. This chronic irritation can cause pigment deposits on the cornea that can lead to impaired vision.
Lagophthalmos
Sometimes, the eyes are so prominent that the lids cannot close all the way over them. This leads to irritation and drying of the center of the eye and sometimes repeated ulceration, pain and possible blindness unless surgical correction is performed. If you cannot tell by watching your pet blink, watch as your pet sleeps to be sure the eyelids close all the way. If the eyelids cannot protect the eyes, pigmentary changes will form where the eyes are chronically irritated and can ultimately cause blindness.
Nasal Fold Irritation
Many brachycephalic dogs have a fold of skin between the nose and eyes. This skin fold needs regular cleaning as it tends to collect skin oil and moisture but it can also be prominent enough to rub on the cornea. Chronic irritation will show as a pigmented area on the eye surface, especially on the side nearest the nose. This is hard to see without a bright light but if it is noted, a search for the cause is warranted. Surgery to remove the excess skin is warranted and does not significantly change the dog’s appearance.
Entropion (Turned-In Eyelids)
The shortened face leads to rolling of the eyelids in such a way that eyelashes or even hairy skin can rub the eye. This is not only uncomfortable but will damage the eye. Some dogs have eyelids that droop or turn out in one area and turn inward in another area (usually the corner of the eye). Surgical correction may be needed to protect the eye and restore comfort.
Dry Eye (Keratoconjunctivitis Sicca)
Brachycephalic breeds tend to get more than their share of tear production problems. In this situation, inadequate tears are produced so a thick, goopy, yellow eye discharge results. In response to the irritation, the eye becomes pigmented and can become blind if treatment is not instituted. This condition is treatable with daily, lifelong medication so it is important to recognize it before it progresses to a point where vision is lost.
Risk of Proptosis
Recognize the prominence of the eyes on brachycephalic. The bony eye sockets are very shallow. This means that any blow to the back of the head, even a fairly minor one, can cause an eye to pop from its socket (proptosis) and require surgical replacement or even removing the eye. This can happen also with too much pulling against the leash if the pet is wearing a collar. You may wish to consider a harness for your pet. Traumatic proptosis is frequently blinding to the eye that was popped out.
Other Concerns
The normal dog has 42 teeth in the mouth. The brachycephalic dog also has 42 teeth but a lot less space to fit them in. This means that the teeth will be crowded and erupt at odd angles which, in turn, traps food debris and leads to periodontal disease at a far younger age than in non-brachycephalics. The earlier you begin using home care dental products, the longer you will be able to postpone full dentistry under general anesthesia.
As mentioned, skin fold infections are common amid the facial folds of the brachycephalic breeds. Be sure to examine these areas periodically for redness. Even if the fold does not rub on the eyeball, it will likely need regular cleaning and topical disinfection to prevent secondary skin infection, pain and inflammation.
The broad-headed nature of these breeds makes reproduction a tricky matter as surgical intervention is indicated to prevent difficult labor. If surgery is not preplanned, difficult labor, and death of the pups or the mother often occur. Surgical assistance is almost always necessary, it is important not to breed females with tracheal stenosis (see above). Brachycephalic breeding is not for the inexperienced and shouldn’t be done for profit as the dangers and risk of death of the dam and puppies are quite high.
Altogether, the brachycephalic breeds show plenty of personality and intelligence, just as all dogs do, but because of their specific needs, their owners need extra knowledge and financial reserves. If you have any questions about your brachycephalic dog, don’t hesitate to call us.
Modified from URL: Brachycephalic Airway Obstruction Syndrome in Flat-Faced Dogs, 4:25 PM