Oral and Nasal Cavities, Pharynx, Guttural Pouches, and Paranasal Sinuses

CHAPTER 4 Oral and Nasal Cavities, Pharynx, Guttural Pouches, and Paranasal Sinuses




Indications for Cytologic Examination





Examination


If disease of the oral cavity is suspected, a thorough examination can usually be conducted in the standing animal. Sedation is often necessary. Food material in the oral cavity may conceal the lesion and should be removed by flushing with water before examination. A mouth speculum also may facilitate visualization. Lesions near the base of the tongue are often difficult to visualize, and careful digital palpation may be necessary. Radiographic evaluation is sometimes helpful, especially if teeth or bony structures are involved.


Diseases of the nasal passages and nasopharynx often require endoscopic examination for adequate visualization.1 Sedation may distort the nasopharynx by relaxation of the soft tissues. Therefore, initial endoscopic examination of this area should be conducted without the aid of sedation if possible. Radiography may also help define the extent of lesions in this area.


The paranasal sinuses on each side communicate and drain into the middle meatus via the nasomaxillary opening. The nasomaxillary opening is not visible endoscopically. However, if nasal discharge is observed endoscopically to originate at the caudal portion of the middle meatus, paranasal sinus disease should be suspected. Confirmation of paranasal sinus involvement requires percussion and often radiography. Once primary sinus involvement is confirmed, the involved sinus can be aspirated for culture and cytologic evaluation.


The guttural pouches can be evaluated by palpation, endoscopy, and radiography. Two different methods may be used to insert a flexible endoscope into the guttural pouch. In the first method, place a biopsy instrument or cleaning brush in the biopsy channel of the endoscope and extend it 2 or 3 cm past the end of the endoscope. Then insert the biopsy instrument or cleaning brush into the guttural pouch opening and rotate the endoscope to open the guttural pouch flap. Then advance the endoscope into the guttural pouch. With the second method, place a Chambers mare catheter into the guttural pouch and rotate to open the flap (Fig. 4-1). Pass the flexible endoscope dorsal or ventral to the catheter and into the pouch as the Chambers catheter is withdrawn.




Sample Collection


Lesions in the oral cavity, nasal passages, nasopharynx, paranasal sinuses, and guttural pouches may be defined by cytologic evaluation, histopathologic examination, and culture (bacterial, fungal). Cytologic samples from the oral cavity are usually limited to fine-needle aspirates of masses or imprints for cytologic examination from excised tissues (see Chapter 1 for a discussion of slide preparation techniques). Cytologic preparations from ulcerative lesions may be collected by imprinting, swabbing, or scraping.







Normal Cytologic Features


The oral cavity and upper respiratory tract are composed of several mucous membrane–lined, communicating passages and cavities: the oral and nasal cavities, pharynx, guttural pouches, and paranasal sinuses. Cytologic samples of the normal oral cavity or upper respiratory tract, collected by washing, swabbing, or brushing, consist of the exfoliated epithelial cells characteristic of the area sampled.


Aug 31, 2016 | Posted by in GENERAL | Comments Off on Oral and Nasal Cavities, Pharynx, Guttural Pouches, and Paranasal Sinuses
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