Brachycephalic syndrome is a pathological condition affecting short-nosed dogs and cats, which can lead to severe respiratory distress. Brachycephalic dogs have been bred so as to possess a normal lower jaw, which 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 owners must be familiar with the needs of their pet.
Some of the breeds affected are Bulldog, Boston Terrier, Boxer, Chihuahua, French Bulldog, Japanese Chin, King Charles Spaniel, Pekingese, Pug, and Shih Tzu. Breeds with less extreme brachycephalia, such as the Boxer, have less compromised thermoregulation and are more tolerant of vigorous exercise and heat. These dogs have been bred to have relatively short muzzles and noses and, because of this, the throat and breathing passages are frequently undersized or flattened. Persian cats also have a brachycephalic conformation.
There are four different anatomical abnormalities that contribute to the disease:
- an elongated soft palate (soft palate is too long so that the tip of it protrudes into the airway and interferes with movement of air into the lungs);
- stenotic nares (malformed nostrils that are narrow or collapse inward during inhalation, making it difficult for the dog to breathe through its nose);
- a hypoplastic trachea (reduced tracheal size); and
- everted laryngeal saccules (tissue within the airway, just in front of the vocal cords, is pulled into the trachea [windpipe] and partially obstructs airflow).
Because all of these components make it more difficult to breathe, in situations of exercise, stress, or heat, an animal with these abnormalities may be unable to take deep or fast enough breaths to blow off carbon dioxide. This leads to distress and further increases respiratory rate and heart rate, creating a vicious cycle that can quickly lead to a life-threatening situation.
Dogs experiencing a crisis situation due to brachycephalic syndrome typically benefit from oxygen, cool temperatures, sedatives, and, in some cases, more advanced medical intervention, including intubation (a breathing tube placed into their windpipe).
Some signs and symptoms of an animal suffering from this condition is breathing with difficulty, noisy, laboured breathing (especially upon inspiration), high pitched wheezing, continuous open-mouth breathing, extending the head and neck to keep airway open, sitting up or keeping chin in an elevated position when sleeping, sleeping with toy between teeth to keep mouth open to compensate for nasal obstruction, blue or purple discolouration of the skin due to poor blood oxygenation in the lungs, stress and heat intolerance during exercise, and snoring, gagging, choking, regurgitation or vomiting. Symptoms progress with age and typically become severe by twelve months.
Some owners of brachycephalic breeds may think their condition is normal for the breed, and may not seek veterinary intervention until a particularly severe attack happens.
This syndrome is diagnosed on the basis of the dog’s breed, clinical signs, and results of a physical examination. Stenotic nares can usually be diagnosed on visual inspection. Diagnosis of an elongated soft palate, everted laryngeal saccules, or other associated anatomical changes in the mouth will require heavy sedation or full general anaesthesia.
Treatment consists of surgery for widening the nostrils, removing the excess tissue of an elongated soft palate, or removing everted laryngeal saccules. Early treatment prevents secondary conditions from developing.
To prevent or limit exacerbation of symptoms, avoid stress and high heated climates. Maintain ideal body weight and avoid overfeeding. Use harnesses instead of collars to avoid pressure on the trachea.
Other health problems associated with brachycephalia include inflammation in skin folds, mating and birthing problems, misalignment of the teeth and overcrowding of teeth, bulging eyes, inward or outward rolling of eyelid, fur around the nose fold rubbing against the eye, abnormally placed eyelashes rubbing against the eye, poor tear production leading to dry eye, and an unusually thick and large tongue, which contributes to the overall obstruction.