Laryngeal Collapse in Dogs
In-depth Information on Laryngeal Collapse in Dogs
Stenotic nares and elongated soft palate can produce marked upper airway noise in brachycephalic (short-faced) breeds of dog, which predisposes these animals to laryngeal collapse. The problem is usually noted in young dogs, less than two years of age. Physical examination, usually under anesthesia will define the abnormalities and distinguish them from laryngeal collapse.
Laryngeal paralysis is not a collapse of the laryngeal cartilage but a failure of the cartilage to open and move outward from the midline. The cartilage itself is usually normal. It is a disorder of the nerves that supply some of the muscles that bring about cartilage opening during inspiration. The definitive diagnosis is made under a light plane of anesthesia. It can be a congenital problem in certain breeds (Bouvier des flandres, Siberian husky), it can be traumatic in origin, but most commonly it is of unknown origin (idiopathic). The dogs affected are very different from dogs with laryngeal collapse; most commonly they are geriatric dogs such as Labradors, golden retrievers and Irish setters.
Tracheal collapse tends to produce a chronic cough ,often a goose-honk cough, but can progress to increased airway noise. Examination of the upper airway would be normal, with diagnosis of collapse in the trachea being made by radiographs, fluoroscopy or tracheoscopy.
Nasal tumors can cause abnormal noise with breathing that is exacerbated by excitement or exercise, but again the dog’s larynx would usually be normal on physical examination. Many dogs with nasal problems will have a nasal discharge that may be bloody or purulent. Diagnosis would be based upon radiographs and biopsy.
Laryngeal and tracheal tumors are uncommon but can produce airway noise similar to laryngeal collapse. Laryngoscopy or tracheoscopy is required to define a mass involving the larynx or the trachea.
In-depth Information on Diagnosis
Brachycephalic breeds of dog, greater than two to three years of age with excessive airway noise should arouse suspicion for laryngeal collapse. Some dogs will have been treated for chronic upper airway problems for some time and be well known to your veterinarian.
A general physical examination should focus on the respiratory system. Listening to the lungs with a stethoscope may not provide much information about the heart and lungs due to the amount of upper airway noise. Your veterinarian should palpate the neck region thoroughly for any laryngeal cartilage abnormalities, such as fractures or growths.
In severe cases, a dog may be in such distress that he turns blue (cyanotic) because of inability to inhale sufficient oxygen. In an emergency situation your pet may require supplementary oxygen by mask, nasal cannula or an oxygen cage; Your veterinarian may choose intubation and place a tube through the larynx and into the trachea to control breathing.
In some emergency situations, the collapse and swelling around the opening of the larynx can make intubation difficult if not impossible and an emergency tracheostomy may need to be performed. This is a surgical incision over the trachea in the middle of the neck to provide an opening to re-route breathing from the mouth.
General anesthesia is required to evaluate the back of the throat and larynx. Prior to this procedure, if the problem is not an emergency, chest X-rays may be taken to assess any concurrent heart or lung disease, as tracheal hypoplasia and narrowing of the trachea, is not uncommon in brachycephalic dogs, and blood may be taken for hematological and biochemical evaluation.
Radiographs may be taken of the neck region to evaluate for abnormalities of the laryngeal cartilage such as tumors or fractures
There are three different stages of laryngeal collapse:
Stage 1 – eversion of the fleshy tissue associated with the vocal cords, called everted laryngeal saccules.
Stage 2 – inward deviation of the lower cartilage of the larynx and/or the folds of tissue around the epiglottis.
Stage 3 – medial deviation of the upper cartilage of the larynx.
In-depth Information onTreatment
Medical management may palliate some of the problems of laryngeal collapse, particularly in its early and milder forms, but it does not usually provide lasting relief for this deformity of the upper airway.
Obese animals should be started on a strict weight loss program that should be carefully and objectively monitored by your veterinarian to ensure that it is producing results.
Exercise must be reduced, as panting will only exacerbate the respiratory distress as the demand for oxygen increases. Likewise excitement should be avoided. These changes in lifestyle may be difficult or unpleasant to adapt and enforce.
A harness should be used instead of a leash as it avoids tugging directly on the trachea or larynx and shifts any pulling force to the chest and sternum.
Corticosteroids may be used to reduce swelling of the fleshy tissue around the larynx, but the long-term use of steroids should be avoided due to systemic side effects.
Sedatives can help to calm a dog that is getting distressed and overheated from the difficulty of not being able to breath or pant properly. These should be used with caution in dogs in severe distress.
Dogs should avoid hot environments, ideally living in an air-conditioned room or with a fan in the summer months.
Surgery should be performed for a more definitive and lasting treatment of the problem of laryngeal collapse.
Any underlying or concurrent abnormalities should be addressed first of all. These would include soft palate resection, correction of stenotic nares, resection of aryepiglottic folds and resection of everted laryngeal saccules. All of these problems add to the negative pressure in the back of the throat that induces collapse in the larynx. When these disorders exist it is like trying to inhale with your mouth closed and your nose pinched. The pressure in the back of the throat sucks the laryngeal cartilage inward, medially, weakening it over time until it becomes flaccid. By addressing these primary causes of airway obstruction early in life, ideally before a brachycephalic dog is two years old, the development of laryngeal collapse should be avoided.
Correction of stenotic nares requires removal of a wedge of tissue and underlying nasal cartilage that is then sutured together to produce a wider opening of the nostrils.
Soft palate resection is performed through the mouth. The palate is shortened to the level of the epiglottis and sutured to seal its fleshy mucosal covering. Carbon dioxide lasers can be used to perform the resection.
Aryepiglottic fold resection and everted laryngeal saccules are removed by an oral approach and just cut out with scissors or a scalpel blade.
Bleeding associated with the palate, aryepiglottic fold and laryngeal saccules is usually minimal, but swelling can occur following the surgery. To offset potential swelling, injectable steroids may be given around the time of surgery.
Some dogs with more severe respiratory distress may benefit from a temporary tracheostomy and for a few days after the surgical procedure. Postoperatively animals undergoing upper airway surgery need to be monitored closely for difficulty breathing, coughing or aspiration of blood associated with the procedure.
More severe laryngeal collapse will only benefit from a permanent tracheostomy. Owners should not rush into this procedure. A permanent tracheostomy requires constant management of the surgical site and often leaves an animal much more prone to pneumonia having lost some of the filtering capacity of the upper trachea and the nasal chambers.
Air does not benefit from the warming and moisturizing affect of being inhaled thorough the upper airway, and this can make bronchial secretions more sticky and less able to move inhaled material up and out of the lower airways.
Dogs with thick necks and severe folds of neck skin are often less than ideal candidates for a permanent tracheostomy, because the skin folds can sit across and obscure the new opening, particularly at night-time when your pet is trying to sleep.
Your pet will receive pain-killers while he is hospitalized and these may be continued at home.