Download DIAGNOSING CANINE CHRONIC NASAL DISEASE

DIAGNOSING CANINE CHRONIC NASAL DISEASE
Chronic nasal disease is a common problem, with many possible causes. The top three differentials in dogs are nasal
neoplasia, lymphoplasmacytic rhinitis and fungal rhinitis. Other causes include nasal foreign body, polyps, mites,
granulomatous rhinitis, oronasal fistula and nasopharyngeal stenosis. Interestingly, while many nasal diseases may
ultimately develop a secondary bacterial infection, primary bacterial rhinitis is rarely reported as a cause of chronic
nasal disease. The treatment of nasal disease, and the associated prognosis, is vastly different depending on the cause
– necessitating the establishment of a definitive diagnosis!
Historically, obtaining a definitive diagnosis for nasal disease was very challenging. However, advances in endoscopy
(rhinoscopy and nasopharyngoscopy) and advanced imaging (CT or MRI) has significantly changed this paradigm.
In one report, using endoscopy and CT, a definitive diagnosis was achieved in more than 95% of nasal disease patients.
A thorough history and physical examination may provide useful information. The age and breed of the patient may be
informative, neoplasia being more common in older dolicocephalic breeds. Systemic diseases tend to cause bilateral
nasal signs, whereas most (but not all) primary nasal disease causes unilateral signs. Hemorrhagic discharge is more
typical of systemic disease or nasal neoplasia, while purulent discharge is more suggestive of a foreign body or an
infectious cause. Depigmentation of the nasal planum raises nasal aspergillosis to the top of the differential list;
whereas boney deformity with absent nasal airflow raises neoplasia to the top of the differential list. None of these
findings, however, are pathognomonic, and their existence does not preclude the need for definitive diagnostic
testing.
Figure 1A: Depigmentation of the nasal planum.
Figure 1B: Computed tomography (CT) of the nasal passages shows unilateral
infiltrative disease. Histopathology and culture confirmed aspergillosis.
CBC, biochemical panel, urinalysis, blood pressure, coagulation testing and thoracic radiographs are important to
assess the systemic health of dogs with chronic nasal discharge (especially in cases of epistaxis) and will, on occasion,
detect an important non-nasal condition. But these tests do not provide a definitive answer. Nasal discharge cytology
and/or nasal wash cytology are frequently nondiagnostic due to poor exfoliation and concurrent inflammation, so are
not recommended. Nasal radiology is also no longer recommended given the need for anesthesia and multiple
studies, and the far superior results obtained by CT. Histopathology ± fungal culture frequently provides a definitive
diagnosis, although in some cases endoscopy is critical to ensure optimum specimens and to rule out underlying
causes (e.g., nasal foreign bodies or mites). CT and endoscopy also enable guided biopsies, increasing the chances for
representative samples (especially important for fungal infections and certain cancers).
Figure 2: Rhinoscopy of a dog with chronic purulent nasal discharge, revealing
nasal mites.
Figure 3: Computed tomography (CT) of the nasal passages of a dog showing
unilateral infiltrative disease. Biopsy and histopathology revealed well-differentiated
nasal adenocarcinoma.
Figure 4A: Rhinoscopy of a dog with severe aspergillus rhinitis.
Figure 4B: Foreign body (piece of plastic) visualized via rhinoscopy (and not via CT)
in a dog with severe resistent aspergillosis.
Please feel free to contact our Internal Medicine Department
with any questions or for consultation at
203.595.2777 or [email protected].
We are here for you and your practice 24/7.
Marnin Forman
DVM, DACVIM (SAIM)
880 Canal Street, Stamford, CT 06902
www.cuvs.org
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