16 Upper Airway Disorders
Foreign bodies are somewhat uncommon and most published reports have documented single cases. No common signalment has been identified. A table reviewing four reported cases is given (Table 16-1). Another report listed six cases of foreign bodies, including grass, cotton, gauze sponge, and a cocklebur. Individual patient descriptions were not available.
Several routes are possible: inhalation through the nares, vomiting, regurgitation, and oral penetration of the soft palate by a foreign object have all been reported. Congenital malformations could also predispose to a nasopharyngeal foreign body.
Clinical symptoms are similar to those described for laryngitis and pharyngitis (e.g., sneezing, stertor). Signs may be acute if a foreign body ingestion or inhalation was witnessed. Dogs with nasopharyngeal foreign bodies are more commonly reported to have halitosis and purulent nasal discharge, especially if the foreign body has a more chronic duration. Also, clinical signs may be improved or relieved with opening the mouth. Alternatively, respirations and signs of stertor may be worsened with holding the mouth closed. In the nonsedated animal, oral examination may be grossly normal.
Differentials, in addition to those listed for laryngitis/pharyngitis should include neoplasia, fungal granuloma (Aspergillus sp.), conformational abnormality, and parasitic infection with nasal mites or aberrant parasitic migration (Cuterebra spp.).
Disease should be localized to the nasopharynx on the basis of history, physical examination, and lack of substantial lesions elsewhere. Lateral skull radiographs have been used to demonstrate nasopharyngeal foreign objects in several cases. It is recommended that animals be placed under anesthesia for adequate radiographic studies. Anesthesia will also permit full nasopharyngeal evaluation. In a normal animal, radiographs of the skull do not show air in the oropharynx and the soft palate should be seen to extend from the hard palate to the epiglottis. Some breed variations do exist (brachycephalic breeds, for example). Radiographs may show a bone, mineral, or soft-tissue density foreign body in some cases. Also, other foreign material may be noted in the stomach. An air-filled esophagus may also be identified; however, interpretation is problematic as a gas-filled esophagus may normally develop while an animal is under anesthesia. Computed tomography of the nasal passages and nasopharynx allows a detailed interpretation of this region and this technology is becoming more readily available. A complete evaluation of the nasopharynx should be obtained, including palpation of the soft palate. Some foreign bodies may be palpated dorsal to the soft palate. The caudal nasopharynx should be visualized with a flexible endoscope or dental mirror, as for laryngitis.
After they are visualized, many foreign bodies can be manually removed with retraction into the oral cavity. Endoscopic retrieval, with grasping forceps, or a basket, may be used. Foreign objects may be digitally pushed from the area dorsal to the soft palate into the mouth. In some cases, flushing saline into the nares can expel a foreign object into the caudal nasopharynx, where it can then be more readily removed. Surgical excision through the palate or via rhinotomy may be required to remove some foreign bodies. After foreign material is removed, the area should be inspected again to ensure there is no retained material and to assess the health of the tissues. In most cases, the prognosis appears to be excellent, though no long-term studies have been performed. Long-term complications (stenotic changes) are possible from scar tissue formation.
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Brachycephalic airway syndrome is a group of anatomical abnormalities normally seen in brachycephalic breeds. This group of anomalies typically includes stenotic nares, everted laryngeal saccules, elongated soft palate, and hypoplastic or collapsing trachea, and laryngeal collapse. These anomalies may occur singly, or animals may exhibit multiple problems.
Brachycephalic airway syndrome occurs in the chondrodysplastic breeds such as the English Bulldog, Pug, Boston Terrier, Pekingese, and Shih Tzu, among others. These breeds have been bred to have characteristics that contribute to their airway difficulties.
Signs of brachycephalic airway syndrome can occur at any age, but typically occur between 1 and 11 years of age. The severity of disease will increase with age. Older animals typically show signs of multiple aspects of the disorder.
The clinical signs associated with brachycephalic airway syndrome are consistent with upper airway obstruction. Noisy breathing may be noted and may be more pronounced with exercise, obesity, or heat. Coughing and gagging may be noted. Signs of dyspnea or cyanosis may also be seen. Animals with brachycephalic airway syndrome may snore and have difficulty with sleep because of periods of asphyxia and upper airway obstruction. Owners may report exercise intolerance. Inspiratory stridor may be noted on physical examination.
In certain chondrodysplastic breeds, as listed previously, early ankylosis of the bones of the skull leads to a shortened longitudinal axis of the skull. This shortening does not affect soft tissues of the head. The shortened skull with excessive soft tissue results in a decrease in airway size and lumen diameter. Animals with brachycephalic airway syndrome typically have stenotic nares, among other anatomic anomalies, resulting in a diminished airway. Also, an elongated soft palate may be found further contributing to the decreased opening of the upper airway. As the airway lumen narrows and pressure increases, other changes occur within the airway. Because of high pressures during inspiration, excess laryngeal tissue (everted laryngeal saccules) may be found, and eventually collapse of the airways (laryngeal and tracheal) may occur.