Page 289 - Small Animal Internal Medicine, 6th Edition

CHAPTER 15 Disorders of the Nasal Cavity 261

of the cribriform plate, and extension of disease beyond the itraconazole is recommended for patients with extension of
nasal cavity impact treatment decisions, as discussed later. disease beyond the nasal cavity and frontal sinuses. Oral
VetBooks.ir binates and fungal plaques, which appear as white-to-green therapy is simpler to administer than topical therapy but
Rhinoscopic abnormalities include erosion of nasal tur-
appears to be somewhat less successful, has potential sys-
plaques of mold on the nasal mucosa (see Fig. 14.12). Failure
conazole is administered orally at a dose of 5 mg/kg q12h
to visualize these lesions does not rule out aspergillosis. Con- temic side effects, and requires prolonged treatment. Itra-
firmation that presumed plaques are indeed fungal hyphae and must be continued for 60 to 90 days or longer. Some
can be achieved by cytology (Fig. 15.3) and culture of mate- clinicians give terbinafine concurrently. In a recent study,
rial collected by biopsy or swab under visual guidance. dogs with nasal aspergillosis that had failed topical and oral
During rhinoscopy, plaques are mechanically debulked by treatment had resolution or significant improvement in clin-
scraping or vigorous flushing to increase the efficacy of ical signs with oral posaconazole (5 mg/kg q12h), terbinafine
topical treatment. The frontal sinuses are included in exami- (30 mg/kg q12h), and doxycycline (5 mg/kg q12h) (Stewart
nation and debriding whenever turbinate erosion allows. and Bianco, 2017). Prolonged treatment was necessary with
Multiple biopsy specimens should be obtained because an average duration of 9 months (range 6-18 months). (See
the mucosa is affected focally or multifocally rather than Chapter 97 for a complete discussion of these drugs.)
diffusely. Best results are obtained when mucosa with visible Successful topical treatment of aspergillosis was originally
fungus is sampled. Invading Aspergillus organisms can gen- documented with enilconazole administered through tubes
erally be seen with routine staining techniques, although placed surgically into both frontal sinuses and both sides of
special staining can be performed to improve sensitivity. the nasal cavity. The drug was administered through the
Neutrophilic, lymphoplasmacytic, or mixed inflammation is tubes twice daily for 7 to 10 days. Subsequently, it was dis-
usually also present. covered that the over-the-counter drug clotrimazole was
Results of fungal cultures are difficult to interpret, unless equally efficacious when infused through surgically placed
the specimen is obtained from a visualized plaque. The tubes over a 1-hour period (70% success with a single treat-
organism can be found in the nasal cavity of normal animals, ment; Mathews et al., 1996). During 1-hour infusion, the
and false-negative culture results can also occur. A positive dogs were kept under anesthesia and the caudal nasophar-
culture, in conjunction with other appropriate clinical and ynx and external nares were packed to allow filling of the
diagnostic findings, supports the diagnosis. nasal cavity. It has since been demonstrated that good distri-
Positive serum antibody titers also support a diagnosis of bution of the drug can be achieved in some cases using a
infection. Although titers provide indirect evidence of infec- noninvasive technique (discussed in the next paragraphs).
tion, animals with Aspergillus organisms as a normal nasal Unfortunately, after a full review of the literature, success
inhabitant do not usually develop measurable antibodies rate following a single topical treatment with enilconazole or
against the organism. Pomerantz et al. (2007) found that clotrimazole was only 46% (Sharman et al., 2010). As a
serum antibodies had a sensitivity of 67%, a specificity of result, the following adjunctive treatments are currently rec-
98%, a positive predictive value of 98%, and a negative pre- ommended in addition to noninvasive clotrimazole soaks.
dictive value of 84% for the diagnosis of nasal aspergillosis. Visible fungal plaques are aggressively debrided during rhi-
noscopy immediately before topical therapy. In dogs with
Treatment frontal sinus involvement, surgical or endoscopic debride-
Topical treatment is currently recommended for nasal asper- ment is performed and clotrimazole cream is packed into the
gillosis, after aggressive debridement of fungal plaques. Oral sinuses. All dogs are reevaluated 2 to 3 weeks after treatment.
Rhinoscopy, debridement, and topical treatment are repeated
if signs persist. In the previously mentioned report (Sharman
et al., 2010), 70% of dogs recovered after receiving multiple
treatments.
For noninvasive clotrimazole soaks (without the place-
ment of tubes through the frontal sinuses), the animal is
anesthetized and oxygenated through a cuffed endotracheal
tube. The dog is positioned in dorsal recumbency with the
nose pulled down parallel with the table (Figs. 15.4 and
15.5). For a large-breed dog, a 24F Foley catheter with a
5-mL balloon is passed through the oral cavity, around the
soft palate, and into the caudal nasopharynx such that the
bulb is at the junction of the hard and soft palates. The bulb
is inflated with approximately 10 mL of air to ensure a snug
fit. A laparotomy sponge is inserted within the oropharynx,
FIG 15.3 caudal to the balloon and ventral to the soft palate, to help
Branching hyphae of Aspergillus fumigatus from a swab of hold the balloon in position and to further obstruct the
a visualized fungal plaque. nasal pharynx. Additional laparotomy sponges are packed