Figure 2.12 Normal nasal turbinates in (a) the dog and (b) the cat.

Mass lesions, fungal plaques, and specific mucosal lesions should be biopsied with visualization to improve the probability of achieving a diagnostic sample. With diffuse or generalized disease, an attempt should also be made to obtain at least the initial nasal biopsy with visualization of the area (Figure 2.13). This can be accomplished either by using a biopsy instrument that fits over the scope, by using a flexible biopsy instrument that passes through the sheathed scope, or by advancing a rigid biopsy instrument along the outside of the rigid telescope. Once bleeding starts, the visual field is usually lost, although intermittent flush and suction can be used to clear the field. Nasal flush can be achieved by attaching a bag of chilled fluids to the biopsy port on the sheath of the scope, or by inserting a red rubber catheter into the nasal cavity and using syringes to obtain a pulsatile pressurized flush. In cats, a 20–60 ml syringe inserted into each naris can be used for nasal flush (Figure 2.14). Nasal flush should also be used if excessive mucus obscures visualization of the nasal cavity. If a foreign body is highly suspected but is not visualized or removed during the procedure, nasal flush will sometimes dislodge the material. The surgical lap pad protecting the endotracheal tube should be removed, examined for foreign material periodically, and replaced with a new one. Also, if a foreign body is suspected, consider placing a Foley catheter in the caudal nasopharynx and using retrograde flush of the nasal cavities to dislodge items (Figure 2.15).

After removing the moistened lap pad from the oral cavity, the airway above the endotracheal tube is suctioned to remove any additional fluid. Before recovery from anesthesia, a complete oral exam and dental probing are recommended to rule out dental disease as a cause for nasal discharge (Figure 2.16).

Figure 2.13 Diagnostic yield of a nasal biopsy sample is improved when the site to be sampled is visualized during the biopsy procedure.

Figure 2.14 Nasal flush can be performed by inserting a syringe tip into the nostril and injecting pulses of chilled saline through each nostril. The animal must be intubated and have a moistened lap pad placed in the oral cavity to protect against aspiration.

Figure 2.15 (a) Right‐angle forceps can be used to place a Foley catheter above the soft palate. (b) The forceps with Foley are inserted into the oral cavity and a spay hook can be used to retract the palate over the balloon portion of the Foley. The balloon is fully inflated and nasal flush can be used to dislodge foreign material or exudate into a collection bowl.

Figure 2.16 A periodontal probe is inserted along the gum lines surrounding each tooth after imaging and rhinoscopy have been completed. Pockets >1 mm depth in the cat and >2–3 mm depth in the dog could result in clinically significant nasal disease due to tracking of bacteria up the tooth root into the nasal cavity.

      Laryngoscopy

      Laryngoscopy can be performed as an isolated procedure or during the preliminary assessment of the airway before a transoral tracheal wash or bronchoscopy. An appropriate anesthetic protocol must be devised that provides a light plane of anesthesia and preserves laryngeal function. While multiple agents are appropriate for use, the key feature is to have spontaneous and vigorous respirations. An assistant is required to identify thoracic inspiratory efforts so that the examiner can insure coordination of laryngeal abduction with inspiration. If the plane of anesthesia is too deep, one to two boluses of doxapram (0.5–1.0 mg/kg) can be used to stimulate respirations (Miller et al. 2002). An accurate laryngeal examination is important because laryngeal dysfunction can be a contributing component to cough in up to 20% of dogs, even when signs of upper airway disease are lacking (Johnson 2016).

Figure 2.17 Necropsy image of the larynx showing the corniculate processes of the arytenoids (co), vocal folds (vf), cuneiform processes of the arytenoids (cu), saccules (s), and epiglottis (e).

Laryngoscopy includes the assessment of function as well as examination of all structures in the area of the rima glottis, including the soft palate, tonsils, laryngeal aditus, and saccules (Figure 2.17). The larynx is inspected for edema, hyperemia, or accumulation of secretions, any of which could indicate injury due to turbulent airflow, acid reflux, or lower airway inflammation. Eversion of laryngeal saccules is a common contributor to obstruction to airflow in the upper airways (see Chapter 4). Because they are membranous tissue, saccules are very responsive to manipulation and can become more swollen as the upper airway evaluation continues, so it is important not to over‐interpret this finding. In the normal dog, the soft palate should not overlap with the epiglottis by more than a few millimeters. Tonsils should be within their crypts; enlargement or eversion is suggestive of inflammation or irritation.

      Bronchoscopy

      Bronchoscopy is one of the most useful techniques for providing a diagnosis in animals with airway or lung disease. It can define the location, grade, and extent of tracheal ring flattening for planning stabilization through surgery or stent implantation, identify protrusion of the dorsal tracheal membrane into the tracheal lumen, document tracheal inflammation or irritation, visualize intrathoracic bronchial or airway collapse, and allow collection of BAL

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