Page 281 - Small Animal Internal Medicine, 6th Edition

CHAPTER 14 Diagnostic Tests for the Nasal Cavity and Paranasal Sinuses 253

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A B

FIG 14.13
Rhinoscopic view through the external naris. (A) A single nasal mite is seen in this dog
with Pneumonyssoides caninum. (B) A thin white worm is seen in this dog with Capillaria
(Eucoleus) boehmi.

cats, however, the diagnosis must be based on cytologic,
BOX 14.2 histologic, and microbiologic evaluation of nasal biopsy
Differential Diagnoses for Gross Rhinoscopic specimens. Nasal biopsy specimens should be obtained
Abnormalities in Dogs and Cats immediately after nasal imaging and rhinoscopy while
the animal is still anesthetized. These earlier procedures
Inflammation (Mucosal Swelling, Hyperemia, Increased can help localize the lesion, maximizing the likelihood of
Mucus, Exudate) obtaining material representative of the primary disease
Nonspecific finding; consider all differential diagnoses process.
for mucopurulent nasal discharge (infectious, Nasal biopsy techniques include nasal swab, nasal flush,
inflammatory, neoplastic) pinch biopsy, and turbinectomy. Fine-needle aspirates can
Mass be obtained from mass lesions as described in Chapter 74.
Neoplasia Pinch biopsy is the preferred nonsurgical method of speci-
Nasopharyngeal polyp
Cryptococcosis men collection. It is more likely than nasal swabs or flushes
Mat of fungal hyphae or fungal granuloma to provide pieces of nasal tissue that extend beneath the
(aspergillosis, penicilliosis, rhinosporidiosis) superficial inflammation, which is common to many nasal
Turbinate Erosion disorders. In addition, the pieces of tissue obtained with
Mild this more aggressive method can be evaluated histologi-
Feline herpesvirus cally, whereas the material obtained with the less traumatic
Chronic inflammatory process techniques may be suitable only for cytologic analysis.
Marked Histopathologic examination is preferred over cytologic
Aspergillosis examination in most cases because the marked inflamma-
Neoplasia tion that accompanies many nasal diseases makes it diffi-
Cryptococcosis cult to cytologically differentiate primary from secondary
Penicilliosis
Fungal Plaques inflammation and reactive from neoplastic epithelial cells.
Aspergillosis Carcinomas can also appear cytologically as lymphoma and
Penicilliosis vice versa.
Parasites Regardless of the technique used (except for nasal swab),
Mites: Pneumonyssoides caninum the cuff of the endotracheal tube should be inflated (avoid-
Worms: Capillaria (Eucoleus) boehmi ing overinflation) and the caudal pharynx packed with
Foreign Bodies gauze sponges to prevent the aspiration of fluid. Intravenous
crystalloid fluids (10-20 mL/kg/h plus replacement of esti-
mated blood loss) are recommended during the procedure
to counter the hypotensive effects of prolonged anesthesia
NASAL BIOPSY: INDICATIONS and blood loss from hemorrhage after biopsy. Blood-clotting
AND TECHNIQUES capabilities should be assessed before the more aggressive
biopsy techniques are performed if there is any history of
Visualization of a foreign body or nasal parasites during hemorrhagic exudate or epistaxis or any other indication of
rhinoscopy establishes a diagnosis. For many dogs and coagulopathy.